Transcript B4B5B6C4C5C6P4P6

• Scientists are interested in the biodiversity of
ecosystems.
• Biodiversity is the variety of life in an area.
• An ecosystem is all the living organisms in a
particular area as well as all the non-living
(abiotic) factors.
• Ecosystems are self-supporting – they contain
everything they need to maintain themselves.
• A population is all the organisms of one species
in a habitat (where an organism lives)
There are various methods to collect animals:
Small mammal trap
Pooter
Pitfall trap
Net
small insects,
e.g. ants
butterflies, etc
small insects,
e.g. spiders
voles, mice
Estimating Population Size Plants
• Quadrats!
• Count the population inside the quadrat.
• Scale up to estimate the population in the
sample area
This is only ever just an estimate!
We can, however, try to make the sample
as accurate as possible:
1) Taking more samples within the sample
area
2) Taking an average of all the samples
3) Placing the quadrat at random
Estimating Population Size Animals
• It is more difficult
estimate
the population
Again, thisto
is just
an estimate.
size of an animals because they move.
We have to make the following assumptions:
1) There has been no change to
the populations
Population size = no in 1st sample x no in 2nd sample
size (death, birth,nomigration)
in 2nd sample that are marked
2) The method used to sample is exactly the
same
Method:
3) The marking
hasn’t affected the survival of
Capture a sample of the population and mark the animals
the organisms.
Release them back into the environment
Recapture another sample. Count the number that are marked.
Use the equation above!
Zonation – describes how the distribution of organisms
changes according to the abiotic factors across a habitat.
Abiotic factors – light, temperature, salinity, water,
oxygen
A line transect is used to show the
distribution of living organisms.
Method:
1) Mark out a line using a tape measure.
2) All the way along place quadrats.
3) Count and record the organisms you fins
in the quadrats.
4) If there are too many organisms to count
accurately you can estimate the %
coverage.
5) Use the data to construct a kite diagram.
Lynne notices that there are
more pale peppered moths
than dark peppered moths.
She knows that there are 300
trees in the wood.
Lynne uses this information to
estimate that there are 60 dark
peppered moths in the whole
wood.
Use the information given to
estimate the number of pale
peppered moths in the whole
wood.
Show your working.
Photosynthesis
6CO2 + 6H2O C6H12O6 + 6O2
Photosynthesis is a two stage process:
Stage 1 – Light energy is used to split water into oxygen gas
and H+ ions.
Stage 2 – Carbon dioxide gas combines with the hydrogen
ions to make glucose and water.
Three limiting factors control the rate of photosynthesis: LIGHT, CARBON DIOXIDE
and WATER.
Greek scientists
concluded that plants
gained mass from soil
(as this was what
they grew in)
Oxygen gas produced
was made from water.
Scientists gave plants
water containing an
isotope of oxygen. They
then found that the
oxygen produced
contained the isotope.
Understanding
Photosynthesis
Priestley proved that
plants produced oxygen
during photosynthesis.
He put a lit candle in with
a plant (which used up
the oxygen). He was then
able to relight the candle
days later.
Van Helmont grew a
willow tree for 5 years.
The tree gained mass
but the soiled stayed
the same. This meant
that plants needed
something else to gain
mass - water
Diffusion is the net passive movement of
particles from an area of high concentration to
an area of low concentration (across a semipermeable membrane)
For photosynthesis to occur the CO2 and H20
needs to diffuse into plant cells.
Cell membranes are selectively permeable:
* CO2, H2O and O2 molecules are small enough
to diffuse through the membranes but other
molecules are too big.
• The rate of diffusion depends on:
– The distance the molecules travel (shorter the
distance the faster the diffusion)
– Concentration difference (greater the
difference the faster the diffusion)
– Surface Area (bigger surface area, faster
diffusion)
Leaves and Photosynthesis
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THIN and TRANSPARENT EPIDERMIS
– to allow light though to inner cells
PALISADE CELLS HAVE LOTS OF
CHLOROPLASTS – maximum
absorption of light energy
CHLOROPLASTS AT SIDES OF
PALISADE CELLS- to allow light to
reach the mesophyll cells
AIR SPACES IN MESOPHYLL- to
allow efficient gas exchange between
cells and air (large surface area)
MESOPHYLL CELLS SMALL AND
IRREGULAR – Increases surface area
to volume ratio so large amounts of
gas can diffuse
BROAD LEAVES – Increases surface
area for light absorption and gas
diffusion.
THIN LEAVES – Short distance for
diffusion.
GUARD CELLS – Control the whether
the stomata are open or closed.
MANY TYPES OF CHLOROPHYLL
Osmosis is the net passive movement of water
molecules from an area of high concentration to
an area of low concentration across a semipermeable membrane)
High water concentration
Low(er) water concentration
Low solute concentration
High(er) solute concentration
When well watered, plant cells in a
plant will take on water by
osmosis. The cells become swollen
(turgid).
The contents of the cell push
against the cell walls and this is
called turgor pressure. This helps
to support the plant tissues.
If there is not a lot of water the
plant cells lose water and lose their
turgor pressure. They’re then said
to be flaccid.
If there is too little water the
cystoplasms comes away from the
cell wall. This cell is said to be
plasmolysed.
Water, Water everywhere.
Roots
are
to plants for photosynthesis
Water
is adapted
needed by
absorbing
and ……water and minerals,
by having :
 to provide dissolved minerals that keep the plants healthy;
LARGE
SURFACE
AREA
 to transport
substances
around the plant;
ROOT HAIRS
 to keep the plant rigid and upright;
THIN CELL WALLS
 to keep
plant
cool;
If plants
losethe
too
much
water
water their cells become
 to allow other chemical reactions to occur in plant cells.
FLACCID
The
CYTOPLASM
What
happens topulls
a plant if it does not get enough water?
away from the cell wall – it
TURGID
FLACCID
becomes plasmolysed
Osmosis
Osmosis in WATER
animal
PLANTS CONTROL
LOSS BY :cells:
Too much water and
Opening and
closing
the cells
burstthe
–LYSIS
stomata
Closing stomata
is
Too littlewhen
wateritand
the cells shrink hot
CRENATION
Small leaves
Stomata on lower
Molecules DIFFUSE from a HIGH CONCENTRATION of
epidermis only
water to a LOW CONCENTRATION of water through a
Stomata close at night
selectively-permeable membrane
Transport in plants
STEM
ROOT
XYLEM
And
PHLOEM
(vascular
bundles)
LEAF
Xylem
Vascular bundles are made up of TWO types of tubes
XYLEM
Features of XYLEM
Strong tubes with RINGS for
support
Carry WATER and dissolved
MINERALS around the plant
Hollow tubes that are DEAD
and PHLOEM
Phloem
Vascular bundles are made up of TWO types of tubes
XYLEM and PHLOEM
Features of PHLOEM
Stacks of individual cells with end
plates
Carry GLUCOSE (food) around the
plant to be stored as STARCH e.g. in
roots such as potatoes and carrots
Have COMPANION CELLS
PHLOEM is LIVING
Transpiration is effected by :
Transpiration
EVAPORATION
of is
Light increases transpiration as moreMARRAM
stomata
open. This
GRASS
from
the
a problem for some plants as they may WATER
lose water
during
leaves causes
the day and wilt.
pressure inside the
plant.
Temperature. High temperature increases
the rate of
-LEAVES with buried
evaporation of water the molecules move
faster
A
stomata. water leaves the
leaves WATER and
Humidity. High humidity means a
higher
amount
water
- LEAVES
curled –ofare
MINERALS
in the air, because of diffusion this
means
less
protected
from
drawn
inwind
through the
evaporation.
roots to replace it.
This
is called
Air movements. Wind blows air CACTUS
away from
stomata
and
– small
leaves
TRANSPIRATION
more water molecules are lost, this
increases
transpiration.
to prevent
water
loss
DEFICIENCIES
Plants need minerals too
growth
NITRATES
– Poor
Making
proteins – GROWTH – making amino acids
which join to makeYellow
enzymes
leaves
PHOSPHATES – Poor
Root root
growth
- phosphorus from phosphates is used to
growth
make cell
membranes and DNA.
discoloured leaves
- Respiration
POTASSIUM
Poor fruit and flowers
– Respiration – use to make enzymes for photosynthesis
Discoloured leaves
- Photosynthesis
MAGNESIUM - Photosynthesis – used to make chlorophyll for
Yellow leaves ( lack of chlorophyll)
photosynthesis
How plants get minerals
Molecules move AGAINST
How do molecules usually pass the
through
membranes?
concentration
gradient
and ENERGY is needed to
move them. This is called
Molecules
move from
ACTIVE
TRANSPORT.
a HIGH
CARRIER
MOLECULES to
CONCENTRATION
transport
the minerals
a LOW
across
the cell membrane
CONCENTRATION
and into
the aplant.
through
selectivelypermeable membrane
Different carrier
molecules will transport
http://programs.northlandcollege.edu/biology/Biology1111/animations/transport1.ht
different minerals.
NPK fertilisers
Fertilisers can have more than one mineral in them.
What minerals do NPK fertilisers contain?
There
are
ratios of
This
isdifferent
NPK 12:12:17
fertilisers.
The numbers mean that the
You arefertiliser
trying tocontains:
grow geranium
plants
that
need lots of
12%
Nitrogen
phosphorous
12%
Phosphorous
Which fertiliser
mix would you
17% Potassium
choose.
NPK 15-15-15
NPK 11-22-16
NPK 16-16-16
NPK 10-10-10
NPK 20-10-10
NPK 12-12-17
NPK 14-14-14
Pesticides in food chains
Why do pesticides build up in a food chain?
Work this out …. DDT (dichlorodiphenyltrichloroethane) is added to
a field and 0.002ppm (parts per million) gets into a river.
1000 microscopic life take in the DDT.
20 fish eat all the microscopic life
1 grebe eats 10 fish.
How much0.002
pesticide
will it
consume?
x 1000
= 2ppm
in microscopic life
2 x 20 = 40ppm in 20 fish
Grebe eats 10 fish so 40/2 = 20ppm
The grebe has a lethal dose of 20ppm
Organic Farming - Cost and Suitability
Farmers produce enough food to feed the world’s
population…But…
 In some countries that have a good climate they
produce excess food.
 In other countries, climate is poor and little food
is produced. Natural disasters and poverty mean
people do not get enough food.
You are a farmer in a poor
country – what decisions would
you have to make on what to do
with your food crop?
Hydroponics
Advantages
• Better control of
mineral supply
• Unused minerals can be
recycled
• Costs can be kept lower
• No pollution
• Better control of
diseases because
plants are under cover
Disadvantages
• Requires use of
manufactured fertilisers
• Tall plants e.g.
Tomatoes need support
Decay
Decomposers such as bacteria and fungi
cause decay.
A decay food chain
Dead animal
Maggots
Common frog
Grass snake
Keywords :
Detritus – dead/ decaying plants and animals
Detritivores – Animals that feed on decaying matter e.g. maggots, flies,
worms
Saprophyte – A plant e.g. fungus that feeds on decaying matter
PREVENTING DECAY
Decaying faster!
Food can be ….
Compost heaps are full of
decay.sealed
As thewhen
organic
CANNED – heated to kill bacteria,
hot matter
– forms
breaks down it releases
VACUUM. Steel used.
minerals that can be used
PICKLED (vinegar) – creates again.
ACID conditions – bacteria
cannot survive.
The bacteria in the compost heap must have a good supply of OXYGEN,
WATER and a correct TEMPERATURE of 37oC to break down dead matter
quickly
SALT or SUGAR ADDED – high concentration causes
OSMOSIS – stops fungal growth
Compost heaps get HOT because micro-organisms RESPIRE and give out
FROZEN
– Kills some bacteria, slows down growth of others
heat energy.
Aerobic bacteria
use Oxygen
to break
down dead
DRIED
– No water
so bacteria
cannot
growmatter quickly.
Anaerobic bacteria ( no oxygen) feed on dead matter without oxygen and
COOKED – High temperature kills bacteria.
this produces acid conditions – slows down decay. They make SILAGE
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Estimating Population sizes
Photosynthesis
Leaves and Photosynthesis
Osmosis
Transport systems in plants
Water flow through plants
Minerals
Decay
Intensive Farming
Biological Control
Alternatives to intensive farming
B5a
Skeletons
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The Human Skeleton
Internal vs External
Skeleton:
• Provides a framework for
the body;
• Grows with body;
• Allows muscles to be
attached easily;
• Has many joint, allowing
greater flexibility;
• Made from living tissue
such as bone cells,
cartilage and blood cells
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Ossification – Process of making bone.
• Before humans are born their
bones are made up entirely of
cartilage;
• As we grow cartilage is slowly
replaced by the addition of
calcium and phosphorus,
making them harder.
• This process is called
ossification.
• If there is no cartilage between
the head of the bone and the
main shaft, then a human has
stopped growing.
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Long bones
• The head of the bone has a covering of cartilage (this
absorbs shock and helps bones to slide over each other in
joints;
• The shaft of the bone contains bone marrow with blood
vessels
• Long bones are hollow, they weigh less and are much
stronger than hollow bones.
• The top of the bone is covered in slippery and hard
cartilage to lubricate the movement against other bones.
• The shaft contains bone marrow and blood vessels.
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Broken bones
• Broken bones are called fractures. There are different
types of fracture:
• Greenstick: When a bone is not completely broken
• Simple: Clean break
• Compound: When the broken bone breaks through the
skin.
• You should never move somebody who has a
suspected fracture:
– Blood vessels and nerves could be damaged;
– If it’s a spinal injury, the spinal cord could be
damaged, this could lead to paralysis or death
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What is osteoporosis?
• It occurs when bones lose an excessive amount
of their protein and mineral content, particularly
calcium. Over time, bone mass, and therefore
bone strength, is decreased.
• a result, bones become fragile and break easily.
Even a sneeze or a sudden movement may be
enough to break a bone in someone with severe
osteoporosis.
• Osteoporosis is more likely as people grow older
and their bones lose tissue.
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Describe the structure of synovial joints
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•
•
•
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Cartilage reduces friction. Acts as a shock absorber.
Synovial fluid lubricates the joint.
Synovial membrane produces synovial fluid.
Tendon joins muscle to bone enabling movement.
Ligament joins bone to bone, stabilising the joint.
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A Ball and Socket Joint: The Hip
A ball and socket joint is a joint in the body that only allows all
around movement. You have this kind of joint in your hip and your
shoulder.
• http://www.youtube.com/watch?feature=pl
ayer_embedded&v=A4Qcjzj3Zs8#!
Describe how the biceps and triceps
muscles operate
• Antagonistic pairs of muscles create movement
when one (the prime mover) contracts and the
other (the antagonist) relaxes
• The origins of both the triceps and the biceps
are at the top of the humerus near the shoulder
joint.
• As the bicep contracts, the lower arm (radius
and ulna) moves up towards the shoulder. The
triceps relax to allow this movement to happen.
• The bicep is the prime mover or agonist, while
the tricep is the secondary
mover or antagonist.
B5a_R.K.Habgood_2013
Explain how the arm bending and
straightening is an example of a lever.
• The movement of the arm is an example of a
lever;
• The elbow acts as a pivot;
• As the bicep muscle contracts, an upward force
is exerted on the arm bones.
• Although the muscle contracts a small distance
the hand can move further.
B5a_R.K.Habgood_2013
• True or false? If it is a false statement then write a corrected
version:
• 1) Bones start off as cartilage in the womb and becomes bone
when calcium and phosphorous are deposited (T)
• 2) All bones contain bone marrow (a spongy substance that
makes new blood cells) (F)
• 3) Osteoporosis occurs when bones lack of calcium and often
occurs in elderly people (T)
• 4) Bones are attached to other bones by tendons (F)
• 5) Bones are attached to muscles by tendons (T)
• 6) The hip and shoulder are known as ball and socket joints –
they can move in all directions (T)
• 7) The knee and elbow are hinge joints – they can only move
backwards and forwards (T)
• 8) Cartilage is found surrounding the whole bone to help protect
it (it acts as a shock absorber) (F)
• 9) Muscles work in pairs (antagonistic pairs). As one muscles
contracts the other relaxes (T)
• 10) To bend your arm upwards the biceps relax and the triceps
contract (F)
• True or false? If it is a false statement then write a corrected
version:
• 1) Bones start off as cartilage in the womb and becomes bone when calcium
and phosphorous are deposited which is known as ossification.
• 2) All bones contain bone marrow (a spongy substance that makes new blood
cells)
• 3) Osteoporosis occurs when bones lack of calcium and often occurs in elderly
people
• 4) Bones are attached to other bones by tendons
• 5) Bones are attached to muscles by tendons
• 6) The hip and shoulder are known as ball and socket joints – they can move
in all directions
• 7) The knee and elbow are hinge joints – they can only move backwards and
forwards
• 8) Cartilage is found surrounding the whole bone to help protect it (it acts as a
shock absorber)
• 9) Muscles work in pairs (antagonistic pairs). As one muscles contracts the
other relaxes
• 10) To bend your arm upwards the biceps relax and the triceps contract
B5b
Circulatory systems and the
cardiac cycle
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What is a single circulatory system?
• A single circulatory system has one circuit
from the heart
• Blood goes around in a single
circuit from the heart
• One chamber receives blood
• One chamber pumps blood
around the body
• Blood pressure is low, as blood
has to flow through a meshwork
of capillaries in the gills before it
reaches the muscles of the body
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Explain why a double circulatory system
links to a four-chambered heart.
• A double circulatory system
has two circuits from the heart.
Blood travels through two
circuits
• Blood pressure is high, blood
is under a higher pressure in a
double circulatory system
compared with a single
circulatory system and how
this allows materials to be
transported more quickly
around the body.
• The right side of the heart
contains deoxygenated blood
• The left side of the heart
contains oxygenated blood
B5b_R.K.Habgood_2013
Describe the contribution of Galen (2nd century)
and William Harvey (17th century) \towards the
understanding of blood circulation.
• In the 2nd century Galen was the first doctor to
realise the importance of the pulse, he believed
that blood in the veins was made by the liver and
the arterial blood was made by the heart.
• In the 17th century, William Harvey explained
that the heart had four chambers and blood
travelled around the body in arteries and veins.
He thought they were joined by tiny blood
vessels, but microscopes at the time were too
small to see capillaries.
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Describe the cardiac cycle
Contraction of the heart = Systole.
Relaxation of the heart = Diastole.
The whole cycle lasts about 0.8 seconds
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Describe the cardiac cycle
Deoxygenated blood flows
from the vena cava into the
right atrium. At the same time,
oxygenated blood flows from
the pulmonary vein into the
left atrium.
SAN sends an electrical impulse which
triggers the atria to contract. Blood is
squeezed through the tricuspid (right
side) and bicuspid (left side) into the
ventricles. The valves close and this
prevents the blood from flowing back
into the atrium.
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Describe the cardiac cycle
The electrical impulses reaches the AVN
which triggers another electrical impulse
which travels along the septum to the
bottom of the heart where it triggers the
ventricles to contract.
The semilunar valves open and
the ventricles squeeze the
blood out into the pulmonary
artery and the aorta from the
bottom upwards. The valves
close and this prevents the
backflow of blood.
B5b_R.K.Habgood_2013
How is heart rate regulated?
• Heart muscle contraction is controlled by groups of cells
called pacemaker cells. There are two types of
pacemaker cells; SAN and AVN
• These cells produce a small electric current which
stimulates muscle contraction.
• Impulses from the sino-atrial node (SAN) generate
electrical impulses, these cause the atria to contract;
• When the impulse reaches the atrio-ventricular Node
(AVN) The AVN is stimulated;
• Impulses from the AVN cause the ventricles to contract.
• Impulses from the vagus nerve (slow down the heart
rate) in the brain and sympathetic nerve (speed up the
heart rate) in the spinal cord can affect the heart rate.
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What is an ECG?
• An electrocardiogram
• Shows changes in the
electrical impulses in the
heart muscles.
• Electrodes are attached
to a patient’s chest sense
change. Any problems
with parts of the heart can
be identified.
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B5c
Running repairs
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Problems with the heart
• Hole in the heart - Blood can move directly from one side
of the heart to the other side of the heart. Less oxygen in
the blood, as oxygenated blood from the lungs mixes
with deoxygenated blood from the body. Can require
correction by surgery
• Blocked arteries – Caused by atherosclerosis. Reduces
blood flow and therefore reduces the amount of oxygen
reaching muscles. Requires a stent or a bypass (where
they take a piece of vein and bypass the blockage)
• Damaged valves – reduces effective blood circulation
and therefore oxygen delivered to muscles. Faulty valves
are replaced by surgery.
B5c_R.K.Habgood_2013
Explain the advantages and disadvantages of
a heart pacemaker or artificial heart valves
over a heart transplant
• If the valves between the atria and ventricles do not work
properly, blood may flow backwards into the atria and
reduce pressure;
• Artificial valves can be used to replace failing or
damaged valves between the atrium and ventricles;
• Using replacement artificial valves or a pacemaker
means a less traumatic and difficult operation;
• Less risk of the body rejecting transplanted organs;
• After a transplant, people have to take immunosuppressant drugs (anti-rejection medications) for the
rest of their lives;
B5c_R.K.Habgood_2013
Recognise that there are ‘heart assist’
devices as well as heart transplants
• A device that helps the heart pump, reduces the
work done by the heart and can be used to give
the heart muscle a rest, they are also used for
patients awaiting a donor heart;
Heart assist devices:
• Reduce the work done by heart muscles;
• Help pump blood around the body;
• Allows heart muscles to recover, and then they
are removed.
B5c_R.K.Habgood_2013
What are the processes of blood
donation?
• Before a person gives blood their haemoglobin
levels are checked. (if their haemoglobin level is
too low the donor would become anaemic);
• The donor’s blood pressure is also checked;
• Once blood is collected, an anti-coagulant is
added to stop it clotting; the blood is labelled
and then stored in a temperature controlled
environment;
• This process of giving blood and packing blood
for storage takes less than an hour.
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What are the processes of blood
transfusion?
• Before a blood transfusion is carried out, the
blood is checked to see that it does not react
with the patient’s blood;
• Blood is slowly introduced into the patient via a
vein;
• Care is taken to prevent air bubbles getting into
the blood, as this can cause a blockage;
• Note: unsuccessful blood transfusions cause
agglutination (blood clumping).
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Describe the process of blood clotting
• Blood clots to heal wounds and prevent the entry
of pathogens and reduce blood loss;
• Alcohol slows down this process;
• The process of blood clotting is called a cascade
process because it involves several stages;
• When platelets (in contact with damaged blood
vessels) are exposed to the air at a wound site,
this triggers a complex sequence of chemical
reactions, eventually forming a meshwork of
fibrin fibres (a clot).
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What are the components of blood?
Platelets: Fragments of cells, form a network
across wounds, important in blood clotting.
Platelets are actually a fragment of a cell. Therefore
they do not have a nucleus.
They are also much smaller than both the white
and red blood cells.
Their role is to help to clot
the blood when the body
has a wound.
skin
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cut
What are the risks of internal blood clots?
• Coronary arteries can get blocked and cause a
heart attack;
• Blood vessels become blocked in the brain,
causing a stroke;
• Drugs such as Warfarin, heparin and aspirin are
used to prevent blood clotting
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Blood groups
• There are four main blood groups:
A , B, AB & O;
• The presence of agglutinins in red blood cells
and blood serum determines how blood groups
react and therefore blood donation.
• Mixing blood from two people can cause
clumping [agglutination]
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Blood groups
Blood groups depend on the presence of
agglutinins that consist of:
• Blood groups are determined by a protein [an
antigen] on the surface of the red blood cell;
• There are two proteins, antigen A & antigen B
found on the surface of red blood cells;
• There are also two antibodies, anti-A or anti-B
found in the blood plasma;
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The Immune Response
-The white blood cells detect
the pathogen
-The white blood cells
produce antibodies specific
to the antigen on the surface
of the pathogen
-The antibodies stick the
pathogens together
(agglutination)
-This happens in blood when
you give somebody the
wrong blood type.
RHD SYSTEM
• The RhD system is important for transfusions;
• 85% of people have the D antigen and are RhD
positive;
• 15% of people do not have the D antigen and
are RhD negative;
• Your blood group is determined by both the ABO
& RhD system.
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B5D
Respiratory systems
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Describe the key parts of the human
respiratory system
• Inhaled air enters the
trachea (wind pipe).
• The trachea branches out
into two bronchi. One in
the left lung, the other in
the right lung;
• The bronchus branch out
into tiny bronchioles;
• At the end of each
bronchiole is an air sac
called an alveoli; this is
where gas exchange
takes place.
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Illnesses of the respiratory system
• Asthma: Lining of the airways become inflamed; fluid builds up in the
airways & muscles around bronchioles contract constricting airways.
(combination of environment, inherited, infectious and chemical factors).
• Asbestosis: (An industrial disease) – Caused by breathing in fine fibres
of asbestos. The fibres get stuck in the alveoli, causing inflammation and
scarring, limiting gas exchange. Asbestos was used as insulation in
building before scientists discovered the risks to health.
• Cystic fibrosis (genetic disorder): Too much mucus in the bronchioles.
• Bronchitis: Bronchitis is an infection of the main airways of the lungs
(bronchi), which causes them to become irritated and inflamed.
• Pneumonia: Pneumonia is inflammation (swelling) of the tissue in one or
both of your lungs. It is usually caused by an infection.
• Lung cancer: Lung cancer is one of the most common and serious types
of cancer. This disease is linked to lifestyle. Factors such as smoking,
exposure to asbestos or radiation and a poor diet all have the dramatic
effect of increasing the risk of developing lung cancer.
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What happens when we breathe in and
out?
Diaphragm moves down
Diaphragm moves up
Intercostal muscles contract
Intercostal muscles relax
Lung volume increases
Lung volume decreases
Pressure decreases
Pressure increases
Air is breathed in
B5d_R.K.Habgood_2013 Air is breathed out
Diffusion of Oxygen & Carbon Dioxide
in the Alveoli
Oxygenated Blood
Deoxygenated Blood
Oxygen diffuses from
the alveoli into the
blood
Carbon dioxide
diffuses from the
blood into the
Alveoli
The blood has
swapped its CO2 for
O2 and is now
oxygenated
Oxygen – high in alveoli, low in
capillaries
Carbon Dioxide – high in
capillaries, low in alveoli
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Alveoli are adapted for
efficient gas exchange
1) Large surface area (due to the
network of capillaries surrounding
the alveoli
2) Moist surfaces
3) A thin permeable lining (one cell
thick)
4) A good blood supply – the
concentration gradient is
maintained by the blood flowing
through
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What do the terms tidal air, vital capacity and
residual air mean? How do you work out lung
capacity?
•
•
•
•
•
A spirometer is used to measure
how much air we breathe in and
out;
tidal air: The amount of
air inhaled or exhaled in
each respiratory cycle, during
a normal, regular breathing.
vital capacity:
The volume of gas that can be
forced out from the lungs at the
end of maximum inhalation
residual air: The amount of air
that remains in the lungs following
a maximal expiration
Lung capacity = residual air +
vital capacity
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Gas Exchange in other organisms
• Most living organisms need oxygen to release energy
from their food by respiration.
• Larger more complex organisms have specialised
organs for gas exchange, such as lungs or gills.
• Smaller organisms like amoeba and earthworms and
amphibians exchange gases through permeable skin.
• Amphibians’ skin and fish gills need to be immersed in
water to allow oxygen to diffuse. Oxygen diffuses
through the amphibians skin.
• Amphibians live in moist habitats; their permeable skin
makes them vulnerable to excessive water loss;
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How are gases exchanged in fish?
• Water containing oxygen enters the fish’s
mouth, then the mouth closes;
• Water containing dissolved oxygen is then
forced over the fine gill filaments;
• The gill filaments have a large surface area;
• Gill filaments have a rich blood supply;
• A bony gill bar supports the gill filaments;
• The Herring also have gill rakers, for filter
feeding, these stop food particles blocking the
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gills.
Explain why the respiratory system is prone
to diseases.
• The air sacs (alveoli) are often described as a ‘dead end’;
• Any debris that is not removed by the mucus and the cilia ,
remains covering and irritating the cells lining the alveoli;
• These cells are thin, moist and delicate to ensure efficient gas
exchange;
• These cells are easily damaged, this is why there are so many
respiratory diseases.
• The production of mucus by specialised cells in the lungs traps
dust particles and some types of bacteria;
• The trachea, bronchi and bronchioles are covered with millions
of hair-like cells, called cilia. These ciliated cells produce a
wave-like movement that carries mucus and trapped dust
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upwards and out of the lungs into the throat.
B5E
Digestion
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In the mouth food is
chewed. This is
mechanical digestion.
Amylase is also
produced which begins
to break down starch
into glucose molecules
The liver makes bile
which is used to
emulsify fats (break
them up into little
droplets). This
increases the surface
area for fat digestion
in the small intestine.
The bile is stored in
the gall bladder.
Food enters the stomach.
The stomach is acidic
(pH2). Here proteases are
produced which begins
to break down proteins
into amino acids.
The food then moves into
the small intestine. Here
fats (lipids) are broken
down by lipases into fatty
acids and glycerol. From
the small intestine the
broken down glucose
and amino acids are
absorbed by diffusion
into the blood
Small Intestine and Food
Absorption
• The intestines are very
long.
• Large surface area for
diffusion because the
walls of the small
intestine are covered in
tiny projections called villi.
• Each cell also has its own
finger like projections
called micro-villi
• Thin lining
• Good blood supply (it is
constantly moving)
• Amino acids and glucose are absorbed
directly from the small intestine into the
blood by diffusion.
• Fatty acids and glycerol can’t diffuse
directly into the blood so they diffuse into
lymph and then into the blood.
Describe the position and function of the
parts of the human digestive system
• Pancreas: produces enzymes and the hormone insulin
(controls levels of blood sugar).
• liver and gall bladder: Liver produces bile and stores
carbohydrates (as glycogen); the gall bladder stores bile.
Bile is important for fat digestion
• small intestine: The first part of the small intestine
produces enzymes for the digestion of carbohydrates,
proteins and fats.
• The second part of the small intestine absorbs the
digested food.
• large intestine: Absorbs water, concentrating the waste.
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Enzymes and digestion -pH
The stomach produces hydrochloric acid.
This helps to begin digestion, and it kills many harmful microorganisms that
might have been swallowed along with the food.
The enzymes in the stomach work best in acidic conditions - in other words, at
a low pH.
After the stomach, food travels to the small intestine.
The enzymes in the small intestine work best in alkaline conditions, but the
food is acidic after being in the stomach.
A substance called bile neutralises the acid to provide the alkaline conditions
needed in the small intestine.
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b5f
Waste disposal
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What are the functions of the key parts of
the kidney?
• Renal artery: takes blood to the
kidneys
• Vena cava: Returns blood to the
heart
• Aorta: Brings blood from the
heart
• Renal vein: Takes blood away
from the kidneys
• Ureter: Takes urine produced in
the kidneys to the bladder
• Bladder: Temporarily stores urine
• Urethra: Sphincter muscles at the
top of the urethra control the
emptying of the bladdder
Waste Removal
• Egestion: The removal of undigested waste, in the form of faeces.
• Excretion: The removal of waste products resulting from metabolic
processes. In plants, waste is minimal and is eliminated primarily by
diffusion to the outside environment. Animals have specific organs of
excretion.
• In vertebrates, the kidney filters blood, conserving water. The
kidneys excrete urea, water and salt in the form of urine. The urine
is then passed through the ureters to the bladder and discharged
through the urethra.
• urine. The skin and lungs, which eliminate carbon dioxide, are also
excretory organs. he act or process of discharging waste matter
from the blood, tissues, or organs.
Why is it important to maintain a constant
concentration of water in the blood plasma?
• It important to maintain a constant concentration of water
in the blood plasma to avoid problems with osmosis and
damaging red blood cells
• In order for our cells to work properly, it is important that
their water content is maintained at the correct balance.
• Our bodies’ must maintain a balance between the water
we take in and the water we lose. This is done by the
kidneys.
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How is the structure of the kidney tubule
(nephron) is related to filtration of the blood
and formation of urine?
useful substances
are removed from
the blood & enter
the tubule here
Blood from the renal artery is
forced into the glomerulus
under high pressure. Most of the
liquid is forced out of the
glomerulus into the [Bowmans]
capsule which surrounds it. This
does not work properly in
people who have very low blood
pressure.
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How is the structure of the kidney tubule
(nephron) is related to filtration of the blood and
formation of urine?
Useful substances are selectively
re-absorbed
Useful glucose is re-absorbed from
the ultra-filtrate and put back into the
blood.
If the glucose was not absorbed it
would end up in your urine. This
happens in people who are suffering
from diabetes.
Losing glucose in your urine is bad
news; how much did those chips at
lunchtime cost you?
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How is the structure of the kidney tubule
(nephron) is related to filtration of the blood
and formation of urine?
The liquid in the collecting ducts
(ultra-filtrate) is turned into urine
as water and salts are removed
from it
The kidneys also have a region for
salt and water regulation.
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Waste
passes to
ureter
How does a dialysis machine work?
• Waste blood containing
urea is removed.
• Urea and uric acid
contain nitrogen and are
poisonous in high
concentrations.
• The machine acts as an
artificial kidney,
removing urea from the
blood.
• Urea molecules diffuse
across a thin
membrane.
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How does a dialysis machine work?
• Dialysis machines have
different sized tubes so
slightly increasing the
pressure during
diffusion. This is called
ultra-diffusion
• The dialysis machine
contains sodium salts,
so that it is the same or
slightly lower than the
desired blood
concentration.
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How does a dialysis machine work?
• This lowers of maintains
or adjust the levels of
sodium in the blood
• Dialysis tubules are
permeable to glucose
molecules, allowing the
glucose levels in the
blood to be maintained.
• The hormone insulin,
that regulates blood
glucose levels is not
removed in dialysis.
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Osmoregulation
b5g
Life goes on
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Describe the hormones of the menstrual cycle
• Follicle stimulating hormone (FSH) Secreted by the
pituitary gland. It causes an egg follicle to develop in
the ovaries. It also stimulates the ovaries to produce
hormones, including oestrogen.
• Oestrogen: Secreted by the ovaries, inhibits the
production of FSH by the pituitary, so no more egg
follicles develop. It also causes the lining of the uterus
to thicken to receive a fertilised egg. Oestrogen also
gives a signal for the pituitary gland to start secreting
another hormone called luteinising hormone (LH).
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Describe the hormones of the menstrual cycle
Leutenising Hormone LH:
• Controls the release of an egg.
• Stimulates the ovary to release an egg (ovulation), in
the middle of the menstrual cycle, when the lining of
the uterus is thickened to receive an egg.
Progesterone:
• Progesterone is also released by the ovaries. It
keeps the lining of the womb thick with blood vessels.
• When the level of progesterone falls, a period starts.
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Explain how negative feedback mechanisms
affect hormone production in the menstrual
cycle.
The production of reproductive hormones by the
pituitary gland [FSH & LH] is controlled by other
hormones [progesterone & oestrogen] produced by
the ovaries.
• FSH: produced by the pituitary gland; stimulates egg
maturation and the release of oestrogen from the ovary
• Oestrogen acts as a negative feedback mechanism to
control FSH. It stops FSH being produced - so that only
one egg matures in a cycle
• Oestrogen stimulates LH production from the pituitary
gland
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Explain how negative feedback mechanisms
affect hormone production in the menstrual
cycle.
• LH controls the release of an egg and
progesterone production
• Progesterone acts as a negative feedback
mechanism to control FSH .
• Progesterone inhibits the production of FSH,
which in turn stops eggs maturing in the ovaries.
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Controlling human fertility
• The hormones that control the menstrual cycle can
be used to treat women who are infertile (who don’t
produce eggs naturally). The woman is given
hormone FSH that causes her ovaries to produce
eggs and to make more oestrogen, so the eggs are
released. Doctors have to be very careful, as too
much hormone will lead to too many eggs being
produced, leading to multiple births.
• Oestrogen is given as an oral contraceptive to inhibit
FSH production. This means that the eggs do not
mature in the ovary and no eggs are released.
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Explain treatments use for treating
infertility?
• Fertility treatments increase a woman's chance of
becoming pregnant, although the treatment may not
always work.
• Multiple births: As fertility treatment boosts the
production of mature eggs, multiple conceptions
sometimes occur, with twins or triplets being
expected. This increases the risk of complications in
pregnancy and childbirth, and may lead to
premature or underweight babies.
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What is IVF?
IVF- In-vito [in glass] fertilisation:
• If a couple are having difficulty conceiving a child
because the quantity or quality of the man’s sperm is
poor then in vitro fertilisation - or IVF - can be used.
• This is where the egg is fertilised outside the woman’s
body and then implanted back into her uterus. As FSH
can also be used to encourage the production of several
mature eggs at once, it is used as part of IVF to increase
the number of eggs available for fertilisation.
• This method is very expensive and very gruelling for the
prospective parents;
• But it can help people conceive who otherwise would not
be able to.
What are the causes of infertility? What
treatments could be used?
• FSH Injections: Some women have low
levels of FSH. This means that their eggs
don’t develop as FSH stimulates egg
development.
• These women can be treated by injecting
them with FSH.
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What are the causes of infertility? What
treatments could be used?
In women: Can’t carry foetus full term;
Treatment: An egg is harvested from the
mother, father’s sperm is collected and
artificially fertilised. The fertilised egg is then
implanted in a surrogate mother
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What are the causes of infertility? What
treatments could be used?
In women: Ovaries stop producing eggs at
a young age;
Treatment: Donor egg used, fertilised and
then placed in the mother;
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What are the ethical issues associated with
infertility treatments?
• FSH injections have been used for many years without
major side effects;
• Surrogate mothers become attached to the developing
baby & not wish to hand over the baby;
• IVF: Low success rate, limited to a small number of
patients. Multiple births;
• Egg donation, egg & resulting baby will be unrelated to
the mother
• Some people worry about the ethical implications of IVF,
and are concerned that couples may only want fertilised
eggs with 'desirable' qualities.
• For example, they may want a girl if they have lots of
boys in the family, or they may wish to avoid producing a
baby with an inherited defect.
Are foetal investigations necessary?
• Blood tests can identify high risks of birth defects
such as spinal bifida, chromosome abnormalities
such as Down’s syndrome, and genetic
disorders like Cystic Fibrosis.
• Recommended for all pregnant women, even if
there are no known genetic disorders.
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Are foetal investigations necessary?
• Amniocentesis: Carried out in over 35 year
olds, in the 15th-18th week of pregnancy. A
sample of the amniotic fluid is taken;
• Can cause a miscarriage in about 1 in 200
cases;
• Parents will face the decision on whether or not
to terminate the pregnancy.
• Amniocentesis tests are carried out in addition to
blood tests, in high risk patients.
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In 1897 JJ Thomson came up with the “Plum
Pudding” model for the atom.
Results from his experiments suggested that
there were small negative charges (“electrons”)
arranged in a sphere of positive charge.
Rutherford and his team (Geiger and
Marsden) investigated further. They carried
out the “gold foil experiment”.
They fired positively charged particles at a
very thin sheet of gold atoms. They found
that most of the positively charged particles
went straight through the atoms and a few
were deflected backwards.
This meant that Thomsons model was
wrong! If Thomsons model was right all of
the particles should have been deflected by
the atom.
A central positive charge
called a “nucleus”.
A cloud of negative
electrons.
Most of the atom is
empty space.
Bohr suggested that electrons were arranged
into “shells” around the nucleus.
Each shell represents an energy level. All
electron in the same shell have fixed energy.
Scientists had realised that if the electrons
were arranged in a “cloud” then they would
be attracted to the nucleus and the atom
would collapse.
-1 charge, 0.0005 mass
+1 charge, 1 mass
0 charge, 1 mass
Relative Atomic
Mass – total number
of protons and
neutrons in the
nucleus
Always the
biggest number!
If the atomic number
tells you the number
of protons and the
relative atomic mass
tells you the total
number of protons
and neutrons then you
can work out the
number of neutrons
by taking away the
atomic number from
the atomic mass:
Neutrons = atomic
mass – atomic number
Atomic Number –
number of protons
(also number of
electrons)
Isotopes – a form of an atom with the same atomic
number (same number of protons) but a different
number of neutrons so it has a different relative
atomic mass.
Going across the periodic table the
atoms are arranged into periods.
Going down the periodic table the
Elements in the same period have the
atoms are organised into groups.
same number of shells
Elements in the same group have
the same number of electrons in
the outer shell.
They all have similar properties
because they have the same
number of electrons in the outer
shell.
In the 1800s, the known atoms were arranged in
order of atomic mass.
In 1828, Dobereiner grouped the known elements
into triads based on their chemical properties.
Lithium, Sodium and Potassium were in one
triad. They have similar properties i.e they react
with water to produce a metal hydroxide.
Newlands noticed that every 8th
element had similar properties so
he organised them into groups of 7
called “octaves”.
His work was not accepted because:
1) His groups contained elements that
didn’t have similar properties.
2) He mixed up metals and non metals
3) There were no spaces for
undiscovered elements.
Mendeleev put the elements in order of atomic mass.
He also placed them into groups according to similar properties. In order to
do this he left gaps. This predicted properties of undiscovered elements.
This layout made sense as we can now fit newly discovered elements into
the gaps.
Rules for drawing electron
configuration
• Atomic number tells the
number of electrons
around the nucleus.
• Electrons always occupy
shells (also known as
energy levels)
• Lowest energy levels are
always filled first.
• First shell – max 2
electrons
• Second shell onwards –
max 8 electrons
• Ca – 2.8.8.2
Progress Check
• 1) How did Rutherford and team prove that
Thomsons “plum pudding” model was
wrong?
• 2) Who suggested the law of octaves?
• 3) How did Mendeleev organise his atoms
(2)?
• 4) Write the electronic configuration for
Aluminium.
Ionic Bonding
Sodium loses an
electron. It now has
more positive
charges than
negative so
becomes positively
charged.
Chlorine gains an
electron. It now has
more negative
charges than positive
so becomes
negatively charged.
• In order to be stable an atom
likes to have a full outer shell.
• One way this can happen is for
atoms lose or gain electrons to
form charged particles (ions)
(depending on how many
electrons they have)
• These ions are then strongly
attracted to each other. (+ to -)
• Normally happens between
groups 1or2 and 6or7.
• Group 1/2 are keen to lose
electrons.
• Groups 6/7 are keen to gain
electrons
Ionic Compounds
• Produce giant ionic
lattices.
• The ions are strongly
attracted to each other
and are unable to move.
• Therefore:
– They have high melting
and boiling points
– They don’t conduct
electricity when solid.
• When melted or dissolved
these compounds will
conduct electricity as the
ions are free to move.
• Draw the ionic bonding for:
– MgO
– CaCl2
Covalent Bonding
• When non-metal atoms combine
together they form covalent bonds
by sharing pairs of electrons.
• This means that each atoms feels
like they have a full outer shell.
• Each covalent bond represents one
shared electron.
• A double covalent bond represents
two shared electrons.
• The atoms within the molecules are
held together by very strong
covalent bonds.
• The forces between molecules,
however, are weak. So they have
very low melting and boiling points.
• They don’t conduct electricity.
Hydrogen Gas (H2)
Chlorine Gas (Cl2)
Methane (CH4)
Water (H2O)
Carbon Dioxide (CO2)
Group 1 – The Alkali Metals
– Group 1 Metals all
• Reacting with water:
have one electron in
their outer shell
– Move around the
– As you go down
surface, fizzing
group 1 the metals
violently and produce
become more
hydrogen.
reactive.
– This is because the
2Na + 2H2O  2NaOH + H2
outer electron is
further away from the
nucleus so less
Sodium + Water  Sodium Hydroxide + Water
energy is needed to
remove it.
Alkali metals burn with characteristic
– They all have low
colours:
melting points, low
density and are very
Lithium: Red
soft.
Sodium: Yellow
Potassium: Lilac
Group 7 – The Halogens
•
•
•
•
•
All elements in group 7 have 7
electrons in their outer shell.
As you go down group 7 the
elements become less reactive
This is because there is less
inclination to fill the outer shell as
its further from the nucleus.
As you go down group 7 the
melting points and boiling points
increase.
At room temp:
– Cl2 is a poisonous green gas
– Br2 is a poisonous orange liquid.
– I2 is a grey solid
Halogens (Group 7) react with Alkali metals (Group 1) to form Metal Salts
2Na + Cl2  2NaCl
Sodium + Chlorine  Sodium Chloride
Displacement Reactions
A displacement reaction can be used to
determine the reactivity series of the
halogens.
http://www.bbc.co.uk/s
chools/gcsebitesize/sci
ence/add_gateway/per
iodictable/group7rev2.
shtml
Superconductors
• At low temperatures, some
metals can become
superconductors. They will
have little or no electrical
resistance.
• Superconductors have
potential benefits, including:
– Power transmission without
losses
– Super-fast electronic circuits
– Powerful electromagnets
– Superconducting
electromagnets are used in
hospital MRI scanners for
example.
Drawbacks:
At the moment, superconductors have to be REALLY COLD. This is expensive to
achieve and takes a lot of energy.
Thermal Decomposition
• When a substance breaks down when
heated.
• Transition metal carbonates break down
on heating.
• CuCO3  CuO + CO2
• You can check the gas is carbon dioxide
by bubbling it through limewater. If it is
carbon dioxide the limewater will turn
cloudy.
Identifying transition metals
• If a solution of any soluble
• You can use this method to
transition metal compound is
identify the transition metal.
mixed with sodium hydroxide
CuSO
solution then we
get4 a+ 2NaOH  Cu(OH)
2 + Na2SO4
•
Copper
hydroxide: blue
displacement
reaction.
Copper (II) Sulphate
+ Sodium Hydroxide

Copper
precipitate (II) Hydroxide +
• The sodium is the more Sodium Sulphate
• Iron (II) Hydroxide: Grey/green
reactive metal, and displaces
precipitate
the transition metal
its  Fe(OH)2
FeSO4from
+ 2NaOH
+ Na2SO4
•
Iron
(III) Hydroxide:
compound.
Iron (II) Sulphate + Sodium Hydroxide Orange/Brown
Iron (II) Hydroxide
+ Sodium
precipitate
• The transition metal hydroxide
Sulphate
is produced as a result. As this
is insolubleFe2(SO4)3
in water it+appears
2NaOH  2Fe(OH)3 + 3Na2SO4
as a solid in the liquid.
Iron (III) Sulphate + Sodium Hydroxide  Iron (III) Hydroxide + Sodium
• A solid produced in a liquid in
Sulphate
this way is called a
precipitate.
• Our drinking water is from reservoirs, lakes, rivers, bore holes, aquifers.
• Why is water important : most of your body is water, life needs it, hygiene.
•
•
•
•
•
•
•
•
•
How do pollutants get into water...
Factory output
Leaks in pipes
Natural disasters
Bad sanitation
Waterborne disease
Lead pipes dissolving into the water
Pesticides
Nitrates from fertilisers
Water
C4
How pure is water?
STEPS
PRECIPITATION
reactions
are used
to test
for nitrate
the
Lead
nitrate
+
sodium
sulphate
----Lead
sulphate
+
sodium
1. Sedimentation
– water.
particles drop to the
presence of IONS in
(White precipitate)
bottom
Pb(NO3)2 + Na2SO4 -------------- PbSO4 (s) + 2NaNO3
IONS
to test for:
Chemical used
2. Filtration
– of particles
using sand
Sulphate SO42- ......... barium chloride
3. Chlorination
– to kill microbes
WATER TESTS
– EQUATIONS
Reactions
Chloride Cl
Write BALANCED symbol equations for these :
Bromide Br……… silver nitrate
Iodide I-
1. Silver nitrate + Sodium chloride
2. Silver nitrate + Sodium bromide
3. Silver nitrate + Sodium iodide
If the ION is present a SOLID precipitate is formed
Identify the correct colour precipitate : WHITE, CREAM or YELLOW
MOLES ahhhhhhh!
• A mole is a pack of particles (single atoms cant be weight, therefore they
are weighed in their moles)
• The mass of one mole is its molar mass (RFM in grams)
For example ... Hydrogen's RFM is 1 ... Its molar mass is 1g
• RFM is relative to 1/12 carbon
Mass
(g)
Moles = how much you have (g)
Mass of one mole
Amount
of
moles
Molar
mass
Avagadro’s number = 6.02x10^23
Amount
of moles
Concent
ration
Volume
(dm3)
C5
Moles!!!!
• A mole is a pack of particlesPractice:
• Molar calculations:
(single atoms can’t be
weighed, therefore they are
1) inHow
66g Carbon
weighed
theirmany
moles)moles are• there
No ofinmoles
= Mass (g)
• In one mole there are
Dioxide?
RFM
602300000000000000000000
Mr of CO2 = 12 + (16x2) = 44
particles.
No of moles = Mass/Mr = 66/44 = 1.5 moles
• 6.02 x1023
• The mass of one mole is equal
2) What
massmass
of carbon is there in 4 Mass
moles of
to its relative
formula
in g
(RFM in grams)
carbon dioxide?
• Molar mass
is measured
in
/
There
are 4 moles
of carbon in 4 moles
of/
grams per mole (e.g carbon
carbon dioxide
has a molar mass of 12 g/mol)
of
Mr (RFM)
Mass = no of moles x Mr = 4No
x 12
= x48g
Moles
Using moles to calculate masses in
reactions …..
• Calculate the mass of aluminium oxide when
135g of aluminium is burned in air.
• Step 1: Write the balanced equation for the
reaction.
• Step 2: Calculate the moles for the part you
have the information for.
• Step 3: Look at the ratio to give you the moles
for the part that you want.
• Step 4: Use the equation mass = moles x Mr
• Calculate the mass of aluminium oxide when 135g of aluminium is
burned in air.
• Step 1: Write the balanced equation for the reaction
•
(4Al + 3O2

2Al203)
• Step 2: Calculate the moles for the part you have the information for.
(moles of aluminium = 135/ 27 = 5)
• Step 3: Look at the ratio to give you the moles for the part that you
want.
(4 moles of Al react to form 2 molesAl2O3 so 5 moles would give
2.5 moles of aluminium oxide)
• Step 4: Use the equation mass = moles x Mr
(mass of aluminium oxide = 2.5 x 102 =255g)
• What is the mass of Sodium needed to
produce 108.2g of sodium oxide?
• (handy hint: 4Na + O2
2Na2O)
Fe and O
• The empirical formula shows you the1)simplest
ratio of
atoms in a compound (C2H6 would become CH3.).
2) 44.8g and 19.2g
• To calculate this, all you need is the experimental
3) Fe(Ar),
- 44.8/56
= 0.8
masses and the relative atomic mass
which
is
O – 19.2/16 = 1.2
found on the periodic table.
4) Fe – 8, O – 12
• Example: Find the empirical formula of iron oxide when
44.8g of iron reacts with 19.2g of oxygen
5) Fe – 8/4 = 2
• There are 5 steps:
O – 12/4 = 3
So . . . Fe2O3
•
•
•
•
•
1) List the elements 2) Write down the experimental masses 3) Divide each experimental mass by the Ar of each 4) Multiply by 10
5) Then see if it can be divided to get the simplest ratio
•
•
•
•
What is the empirical formula of
a) C7H14?
b) C6H12O6?
c) Al2O6?
• Find the empirical formula when:
• a) 2.4g of carbon react with 0.8g of hydrogen
• b) 21.9g of magnesium react with 29.3g of sulfur
and 58.3g of oxygen
Concentration
• Concentration is a
measure of how
crowded particles are.
• The more crowded,
the more
concentrated.
• Concentration = no of
moles / volume
No of
Moles
/
Conc
(mol/dm3)
/
X
Volume
(dm3)
Converting concentration from
mol/dm3 to g/dm3
• Example:
• You have a solution of
sulphuric acid of
0.04mol/dm3. What is the
concentration in g?
• STEP 1: Work out RFM
• H2SO4 = 98
• STEP 2: Convert the
conc in moles to conc in
grams. So in 1dm3
• Mass = moles x RFM
• 0.04 x 98 = 3.92 g
Mass
(g)
/
No of Moles
/
X
Mr
(RFM)
Titrations
• Titrations are used to find out exactly
how much acid is needed to
neutralise an alkali or vice versa.
• It can then be used to calculate
unknown concentrations.
• Method:
Titrations use single
indicators so it makes it
easy to see the end point of
the titration.
E.G phenolphthalein
Universal indicator is made
from a mixture of different
indicators so each colour
indicates a range of pH
values.
– Fill a conical flask with 25cm3 alkali
of unknown concentration
– Add 2-3 drops indicator
– Fill a burette with acid
– Using the burette add the acid a bit at
a time (say 5cm3)
– When indicator changes colour you
have reached the end point. You now
have a rough estimate of how much
(to the nearest 5cm)
– Now repeat adding a smaller amount
of acid each time.
– To increase the accuracy you need to
get several consistent readings!
• Concentration = moles x volume
• Calculating Unknown Concentrations:
• Step 1: Work out how many moles of the
“known” substance you have.
• Step 2: Write the balanced symbol equation for
the reaction. Work out how many moles of the
“unknown” stuff you had.
• Step 3: Work out the concentration of the
“unknown” stuff!
•
Concentration = moles x volume
•
You start off with 25cm3 of sodium hydroxide that has a concentration of
0.100 moles per dm3. It takes 49cm3 of hydrochloric acid to neutralise the
sodium hydroxide. What is the concentration of the hydrochloric acid used?
•
•
Step 1: Work out how many moles of the “known” substance you have.
Number of moles = conc x volume
= 0.1 x (25/1000)
= 0.0025 moles of sodium hydroxide
•
Step 2: Write the balanced symbol equation for the reaction. Work out how
many moles of the “unknown” stuff you had.
NaOH + HCl  NaCl + H2O
For every mole of NaOH, you need one mole of HCl
So you must need 0.0025 moles of HCl
•
•
•
•
•
Step 3: Work out the concentration of the “unknown” stuff!
Concentration = no of moles / volume
= 0.0025 / (49/100)
= 0.0510 mol/dm3
When you do a titration there is a gradual change in
pH. At the end point there is a sudden change in pH.
The rate of a reaction can be measured
by the amount of gas produced.
Gas Syringe
Upturned measuring
cylinder/burette
Mass Loss
Method
Gas Syringe
Pros
Can be used to collect
pretty much any gas.
Accurate volumes – to
the nearest cm3
Upturned
measuring
cylinder
Mass Loss
Accurate volumes – to
the nearest cm3
Greater accuracy.
Cons
If the reaction is too
vigorous it can blow the
plunger out of the
syringe.
Cannot collect gases
such as Hydrogen
chloride or ammonia as
these dissolve in water.
Gas is released straight
into the room so not
suitable for reactions
that produce poisonous
gases.
Interpreting Rates of Reaction
Amount of Product
Steeper gradient –
End of Reaction
faster rate of reaction
More
reactant
Time
Equilibrium
an Equilibrium
– the
Process
• The Reaching
Haber Process
is an example
of Haber
a reversible
reaction.
1) Asand
nitrogen
and hydrogen
reactammonia
together their
• Nitrogen
Hydrogen
react to make
and the
ammonia
breaks downfall.
to make
nitrogen
hydrogen.
concentrations
The initial
rateand
of reaction
• N2 + 3H2 2NH3 will begin to slow down.
2) As more
and more
product ammonia
• Reversible
reactions
reachof
anthe
equilibrium
– whereisthe
made,
its concentration
risestoand
begins
to
rate of the
forward
reaction is equal
theitrate
of the
backward reaction
turn back into nitrogen and hydrogen.
3) only
As more
is made,
the rate
of the– reverse
• This can
happen
in a closed
system
where none
of the products or reactants
escape.
reaction can
speeds
up.
4) After a while the forward reaction will be going
at the same rate as the backward reaction.
•
•
•
•
•
The position of the equilibrium can be in the middle, to the left or to the
right.
This tells us about the amounts of the products and reactants.
If the equilibrium is in the middle then there are the same amounts of
reactants as products.
If the equilibrium is to the right then there is more product and not so much
reactant.
If the equilibrium is to the left then there is more reactant and not so much
product.
Product
Reactant
Reactant
Equilibrium
Product
C5
Changing Equilibrium
• Three factors affect the position of the
equilibrium:
Temperature
For all reversible reactions, one direction is an exothermic
reaction and the reverse direction is endothermic.
If you decrease the temperature, the rate of the endothermic
reaction will decrease. Therefore the equilibrium will shift towards
the exothermic reaction so that more heat is produced.
Exothermic
Endothermic
Changing Equilibrium
• Three factors affect the position of the
equilibrium:
Pressure (only for gases)
If you increase the pressure the equilibrium tries to reduce it. The
equilibrium moves in the direction where there are fewer moles of
gas
Changing Equilibrium
• Three factors affect the position of the
equilibrium:
Concentration
If you increase the concentration by adding more of the reactants,
the equilibrium tries to reduce this concentration (so more product
is made)
If you increase the concentration of the product the the equilibrium
shifts to reduce this so more turns back into the reactants.
The contact process
1. Burn sulphur in air to make sulphur dioxide
S + 02
SO2
2. React sulphur dioxide with more oxygen in air to create
sulphur trioxide
2SO2 +02
2SO3
Reactprocess
SO3 with
to make
makesSulfuric
sulphuric
acid
The 3.
contact
is water
used to
Acid.
It is made
C5 of
three mainSO3
steps.
Because part ofH2SO4
the process involves a
+ H2O
reversible reaction, the conditions are carefully controlled to get a
higher yield.
Conditions for the Contact Process
• For the most economic yield the reaction is carried out
at:
• ~450 oC (this is a compromise, forward reaction is
exothermic so high temps reduce yield and shift
equilibrium to left. But, at high temps rate of reaction is
quicker so chemical is produced faster)
• Atmospheric pressure (another compromise, there are
3 gas molecules on the left of the equation and 2 on
the right so high pressure increases yield by forcing
equilibrium to the right. However, equilibrium already
lies to right so the cost of thicker walls etc. to
withstand higher pressure is not economical)
• Using a catalyst of vanadium pentoxide (V2O5) (this
does not affect the position of the equilibrium but
makes the reaction go faster so more product is
produced)
Strong and Weak Acids
• Strong Acids ionise completely in water. This means that
the compound dissociates (e.g HCl  H+ + Cl-). There is
a higher concentration of H+ ions ready to react.
• Weak Acids only partially ionise in water. It is a reversible
reaction which sets up an equilibrium mixture.
• (e.g CH3COOH
H+ + CH3OO-)
• Only a few H+ ions are released at once so the
equilibrium is off to the left.
• Once these H+ ions have been used up a few more are
released.
• Strong acids are better electrical conductors because
they have a higher concentration of hydrogen ions to
carry the charge.
Redox Reactions
• Redox reactions occur when electrons are transferred
between particles.
• Particles that lose electrons become oxidised
• Particles that gain electrons become reduced.
• REDuction, OXidation.
•
•
•
•
•
Oxidation is Loss,
Reduction is Gain
OIL RIG
Oxidising Agent – accepts electrons
Reducing Agent – donates electrons
Examples of Redox Reactions
• Chlorine gas is passed into a solution of iron (II)
salt (Fe2+). The iron (II) becomes iron (III)
(Fe3+). The Chlorine becomes Cl• Iron is oxidised (Fe2+ - e-  Fe3+)
• Chlorine is reduced (Cl2 + 2e-  2Cl-)
• Iron is the reducing agent.
• Chlorine is the oxidising agent.
Examples of Redox Reactions
• Iron reacts with oxygen and water to form
hydrated iron oxide.
• Iron is oxidised (Fe - 3e-  Fe3+)
• Oxygen is reduced (O2 + 4e-  2O2-)
• Iron is the reducing agent.
• Oxygen is the oxidising agent.
Examples of Redox Reactions
• Displacement Reactions – Put iron in a solution of tin
sulphate and the iron will swap places with the tin
making tin and iron sulphate.
• Iron + tin (II) sulfate  iron (II) sulfate + tin
• Iron is oxidised (Fe + SO4-  FeSO4 + 2e-)
• Tin is reduced (Sn2+ + 2e-  Sn)
• Iron is the reducing agent.
• Tin is the oxidising agent.
Preventing Rusting
• 1) Making alloys e.g steel
• 2) Painting and oiling/greasing
• 3) Galvanising – coating with a tin plate
• 4) Sacrificial Protection – place a more reactive
metal with the iron. The water and oxygen will
react with this instead.
• Electrolysis is the breaking down of a
substance using electricity.
• An electric current is passed through a
molten or dissolved ionic compound
causing it to decompose.
• This creates a flow of charge.
• Electrolysis of aqueous
sulfuric acid.
• Ions: H+, OH-, SO42• Hydrogen ions accept
electrons from the
cathode to make
hydrogen gas.
• At the anode, hydroxide
ions lose electrons to
make oxygen gas
• Products:
– Cathode: Hydrogen (2H+
+2e-  H2)
– Anode: Oxygen (4OH- -4e O2 + H20
• Electrolysis of aqueous sodium hydroxide.
• Ions: H+, OH-, Na+
• Hydrogen ions accept electrons from the
cathode to make hydrogen gas.
• At the anode, hydroxide ions lose electrons to
make oxygen gas
• Products:
– Cathode: Hydrogen (2H+ +2e-  H2)
– Anode: Oxygen (4OH- -4e-  O2 + H20
• Electrolysis of copper
sulfate using carbon
electrodes.
• Ions: Cu2+, H+, OH-,
SO42• Copper ions accept
electrons from the
cathode to make copper.
• At the anode, hydroxide
ions lose electrons to
make oxygen gas
• Products:
– Cathode: Copper (Cu2+
+2e-  Cu)
– Anode: Oxygen (4OH- -4e O2 + H20
In electrolysis what determines
which anion/cation is easier to
discharge
• The ion discharged first is the one which is
lower in the reactivity series.
E.g. Hydrogen is discharged in the
electrolysis of brine leaving sodium Na+
ions in solution.
What’s the link between current and
charge when talking about electrolysis?
• The amount of product is proportional to
time and current
• Q = It
• t Time (seconds)
• I Current (amps)
• Q Charge (coulomb)
• Example question:
– A current of 0.1A for 2 hours increased the
mass of an anode by 0.24g. How much
charge was transferred?
Electrostatics Video
Uses of Electrostatics
Paint Spraying
• Spray Gun is charged – all of the paint gets the same
charge
• Like charges repel – paint particles spread out giving a fine
spray
• Object being painted is given the opposite
charge – paint is attracted to object and sticks to it.
• Advantages : less wasted paint; even coat of paint; awkward places are painted.
Electrostatic Dust Precipitators
• Removes harmful smoke particles from a chimney.
1.Metal grid/wires placed in chimney
2.Grid connected to high voltage supply
3.Dust particles attracted to metal grid
4.Dust particles stick together
5.Large particles fall down chimney
6.Soot used to make building blocks
Electrostatics & Uses of
Electrostatics Tests!
Mains Electricity Video
Current Electricity
• Electric Circuits – must be COMPLETE to allow
electricity to flow from + to – terminals on a cell/battery.
• A Cell provides POTENTIAL DIFFERENCE
(Voltage) in VOLTS. This provides the FORCE to move the
charge carriers (in wires – electrons; in electrolysis – ions)
• The resulting flow of charge is called
CURRENT measured in AMPS.
• Current always flows from + to – (even though the
electrons flow from – to +!)
A Circuit to measure resistance
A variable
resistor varies
the current in
the circuit
Resistance =
Potential difference
÷ Current
R=V÷I
The component
which is having
its resistance
measured
A
An ammeter
measures
Current in Amps
V
A voltmeter
measures Potential
Difference in Volts
Ohm’s
CoverLaw
up
what you
want to find
V
÷ ÷
R x I
• “For a metallic conductor at constant
temperature, the ration of Potential
difference (V) to Current (I) is constant”.
• The constant is called Resistance, R
measured in ohms, symbol Ω.
• So R = V ÷ I, also V = I x R and I = V ÷
Mains Electricity
• Live (brown) brings
supply to house
• Neutral (blue) is return
path to power station
• Earth (green and yellow)
carries current to 0V if
the casing becomes
live. This blows the
FUSE which cuts off the
supply.
• Fuse is in series with
the Live wire.
Fuses come in various
values; 2A,3A,5A,13A.
A 13Amp fuse blows
when current through it
exceeds 13Amps
A circuit-breaker is a re-settable fuse which can be
re-set at the flick of a switch
These have replaced fuse wire in the main fuse box.
Electrical Circuits Test!
Ultrasound -
sound waves beyond the human hearing range
• Range of human hearing is 20 –
20,000Hz so beyond that is Ultrasound
Sound waves are LONGITUDINAL – the vibrations of
the particles are in the same direction as the wave
Compression – particles in wave squashed
together
Rarefaction – particles in wave spread out.
Wavelength – distance occupied by one
complete wave (unit – metres)
Frequency – number of complete waves per
second (unit – hertz)
Amplitude – maximum distance a particle
moves from its normal position.
Uses of Ultrasound
•
•
•
•
Check the condition of a foetus
Investigate heart and liver problems
Look for tumours in the body
Break down kidney stones and stones
elsewhere in the body
• Measure the speed of blood flow in
vessels when a blockage of a vein or
artery is suspected
• Cataract surgery
Non – medical uses : dentists shake plaque and dirt off teeth;
jewellers clean delicate pieces of jewellery and watches
Radiotherapy and Diagnosis
• Gamma rays γ

X rays
•

High frequency/energy
electromagnetic waves
emitted when high speed
electrons are decelerated
Very penetrating
Can damage living cells
An X-ray machine can
produce and control X-rays
of different energies – so
some X-rays can have
higher energy than γ rays
•
•
High frequency/energy
electromagnetic waves
emitted from the nucleus
of a radioactive isotope
Very penetrating – can
pass into the body to
treat internal organs
Can damage living cells
– over exposure should
be avoided



Alpha, Beta and Gamma emissions
Radiation
Alpha
Beta
Gamma
Ionising Power
Very strong
Medium
Weak
Range in air
About 5cm
About 1m
Very large, its
intensity
decreases with
distance
What stops it?
paper
A few mm of
Aluminium
Reduced by lead
and concrete
Ionisation – the ability to remove an electron from an atom, causing
the atom to become charged.
Alpha has 2 + charges so has a great ionising effect, beta has 1 – charge
so a lesser ionising effect.
Alpha and Beta particles are not good inside the body – they cannot escape from inside – so
don’t swallow any – remember Mr Litvinienko? – killed with Polonium 210, an alpha emitter!
Using Gamma radiation
• Treating cancer – large doses can kill
and destroy cancer cells. A ‘gamma knife’ is
rotated around a cancer to give the cancer a
high dose but the healthy tissue a low dose.
Side effects of this kind of therapy can be
unpleasant but slows down the growth of the
cancer.
• Sterilising hospital equipment –
Gamma
kills bacteria
prevents
Tracers
– some
radioactiveand
isotopes
of disease.
(in very
low doses!) can be injected into the
body to highlight places where a cancer may
be growing.
Common isotopes are
Technetium – 99 and Iodine - 123
Radiographers –
the spread
carry out procedures
using X-rays and
nuclear radiation.
Lead prevents tissue
absorbing radiation.
Radioactivity - discovered by Becquerel and researched
by Pierre & Marie Curie (among others)
• Some atoms naturally break up because the nuclear
forces holding them together are not strong enough.
• Radioactive substances decay naturally and give out
Alpha (α), Beta (β) and Gamma (γ)
radiation.
• Radioactivity is a random process that cannot be
controlled by external conditions such as
temperature, pressure etc. Neither can the decay be
predicted.
• Radioactivity is detected usually with a GeigerMüller (GM) tube and a ratemeter.
• Activity is measured by counting the average
Half Life
• The time taken for
the activity of a
sample to fall to one
half of its original
activity,
OR
• The time for half of
the atoms in a
radioactive isotope
to have decayed.
• It is different for
A Typical Decay curve
every
radioisotope
Remember : A is the mass number = protons + neutrons
Z is the proton number = number of protons OR electrons
Alpha Decay
•
An alpha particle (or helium nucleus) contains 4 nucleons (2p
+ 2n)
•
•
When α is emitted, A decreases by 4, Z decreases by 2
The new element formed is two places lower in the Periodic
table than the original radioisotope.
238
•
92
4
U
2
234
α + 90Th
0
Beta Decay - β
1
• A beta particle is a high energy electron
emitted from the nucleus (!)
[This is because a neutron decays to a proton, an electron and a bit of antimatter]
•
When β- is emitted,
A does not change
Z increases by 1
(because it has an extra proton).
14
6
•
0
C
-1
14
β + 7N
A new element is formed that is one place higher in the periodic
table than the original radioisotope.
Background Radiation
• This is ionising radiation that is always
present in the environment.
• The level of background radiation is low and
does not cause harm.
•
E.g. Granite contains small amounts of Uranium which decays to
Radon, a radioactive gas.
• Sources (7): radioactivity in the air; radiation
from Space (cosmic rays); rocks; food;
medical uses; nuclear power; nuclear
weapons testing (these last two make up just 1%).
Uses of Radioactivity
• Alpha is used in Smoke detectors Americium-241
• Beta is used to monitor the thickness of paper –
Strontium-90
• Gamma is used to treat cancer; to search for leaks from
pipes; to check welds in castings.
Dating:
•Uranium/Lead levels are used to date rocks – VERY OLD!
•Potassium/Argon levels date rocks up to about 100,000 years old
•Carbon 14/Carbon12 levels are used to check organic material up to 60,000 years old
What is radioactivity? Uses of
radioisotopes & Radiation
treatment tests!
Nuclear Fission
•U235 can become unstable
when bombarded with
neutrons.
•It accepts a neutron, becomes
U236, which decays readily to
Kr92, Ba141 and extra neutrons.
(These may go on to strike the nuclei of other
atoms causing further fission reactions –
a CHAIN REACTION).
•It also releases
massive amounts of
energy!!!
A Nuclear Power Station
Control Rods in
a reactor core
The output of a Nuclear Reactor is controlled by:
A graphite moderator between the fuel rods slows down fast-moving neutrons
Boron control rods absorb neutrons and so control the rate of fission.
P6
Potential Dividers
• A potential divider is made up of two
resistors and shares the voltage as
required (e.g. volume/balance/tone on a
hi-fi)
• The output voltage from a potential divider
will be a proportion of the
input voltage and is
determined by the
resistor values
Potential Dividers
• Consider a standard resistor connected
across a voltage supply. If you were able to
measure the voltage at any point along it you
would find the voltage varied linearly, e.g.
– if the resistor was
connected between 10V
and 0V the voltage
half-way along it would
be 5V
– Similarly the voltage 10%
from the 0V end would be 1V
Potential Dividers
• A potential divider works in the same way.
Obviously a resistor is normally enclosed
so you can't tap the voltage off at any point
along it, so two resistors are
used; the tap point
being between these
resistors
Calculating the p.d. OUT
• When one of the pair of resistors in a
potential divider circuit is a variable
resistor, the value of the output p.d. can be
altered
Vout=Vin x ( R2 )
R1 + R2
LDRs
• Streetlights have potential
divider circuits
• When it’s dark, the
resistance of the LDR is
high, which means that the
p.d. OUT is high and can
be used to switch on the
light
• If the positions of the LDR
and fixed resistor (variable
resistor shown in diagram)
are reversed, the p.d. OUT
decreases as it gets darker
Thermistors
• Thermistors can also
be used in a potential
divider circuit
• When the temperature
falls, the p.d. OUT rises
and can be used to
switch on a heater