Transcript Chemistry Chemical Reactions 1x

Chemistry!
Matter
• Matter is anything which has mass and volume
• Different types of arrangements of matter make
up different things
– Mass: The quantity of matter in an object
– Volume: The amount of space an object takes up
– Density: Two objects can have the same volume but
different mass
– Weight: The force of gravity on an object
• The more mass an object has, the greater the weight
Chemical vs. Physical
• Physical properties: Can be observed and
measured
– Color
– Mass
– Volume
– Shape
– Melting Point
– Boiling Point
Chemical vs. Physical
• Chemical properties: Behavior of a substance
during a chemical reaction
– Toxicity
– Flammability
– Reactivity
– Acidic or Basic
Chemical vs. Physical
• Physical Change: A change which does not
change the substance’s chemical identity
– It is still the same substance
• Painting a piece of wood
• Freezing water
• Tearing a piece of paper
Chemical vs. Physical
• Chemical Change: The change of one
substance into another
– Burning a piece of wood
– Cooking food
– Rusting metal
Chemical vs Physical
• Which of these changes are physical, which
are chemical?
– Frying an egg
– Boiling water
– Painting a car
– Digesting food
– Crumbling a piece of paper
– Decaying leaves
So what is matter made up of?
• Made up of individual atoms
– An atom is the basic unit of matter
• An atom is made up of even smaller particles
called subatomic particles
Atoms!
• The center of the atom is called the nucleus
– This is made up of protons and neutrons
– The nucleus makes up 99.9% of the mass of an
atom
– The proton is positively charged
– The neutron is neutrally charged
– The electron is negatively charged
Electrons
• Electrons circle around the nucleus
– Have a negative charge
• The number of electrons equals the number
of protons giving the atom a neutral charge
Reactions
• Bonding of atoms is an example of a chemical
reaction
• A chemical reaction occurs when there is a
chemical change
– Digestion
– Combustion
Chemical Reaction
• Represented by a chemical equation
• Process which atoms or groups of atoms are
reorganized into different substances
– Ex: Rust on a car
• Reactants
products
– Reactant: Substance that enters into a reaction
– Product: The result of a reaction
Chemical Reaction
• Reactants are the starting substance
• Products are the substances formed
• So… which ones are the reactants and which
are the products
• C6H12O6 + 6O2
6CO2 + 6H2O
• How about this?
• 6CO2 + 6H2O
C6H12O6 + 6O2
Activation Energy
• Minimum amount of energy needed for
reactants to form products in a chemical
reaction
– Candle/wick
– Flame is your activation energy
Enzymes and Catalysts
• Catalyst: Lowers the activation energy that is
needed in order to start a reaction
• Enzymes: Proteins (biological catalyst) that
speed up the rate of chemical reactions in
biological processes
– Enzymes always end in “ase”
– Ex: Amylase in saliva breaks down starch
Water!
The Chemical Basis of Life
The Importance of Water
1. Life evolved as a result of water.
2. All life on earth requires water.
3. ¾ of the earth’s surface is covered by
water.
4. 2/3 of your body is composed of water.
5. Water is a liquid at most temperatures on
the Earth’s surface.
Hydrogen Bonding
 Water molecules are polar molecules
The Oxygen atom attracts more electrons giving the
Oxygen atom a negative charge. (Electron rich)
The Hydrogen atom is positively charged. (Electron
poor)
Because of the charges, a water molecule has polarity.
a. Similar to a magnets + and – ends.
The positive and negative ends of the water molecule
attract other water molecules
That’s Hydrogen Bonding!
Mixtures or Solutions
1. Mixture – A substance composed of two or more
elements or compounds that are mixed together
but not chemically combined.
1. Can be separated
2. Solution (A type of mixture) – A uniform
(homogenous) mixture of two or more substances.
a. Solvent – Substance that does the dissolving.
b. Solute – The substance that is dissolved.
Example: In a salt water solution…
• Is salt the solute or the solvent?
– Solute
• Is water the solute or the solvent?
– Solvent
• What does the solute do?
– Gets dissolved
• What does the solvent do?
– Does the dissolving
A Salt Water
Solution
Solute
(salt)
Solvent
(water)
Water is considered a universal solvent
• MANY substances dissolve in water.
– This makes it a universal solvent
 If a substance doesn’t
dissolve in water it’s
non-polar.
 Non-polar means that
the molecule does not
have a charge on it.
 Water cannot form a
solution with a nonpolar substance.
Non-Polar
Non-polar oil molecules
Polar water molecules
Adhesive Properties
• Adhesive
properties of water
– Water’s ability to
stick to other
substances.
• Water sticking to
and climbing up a
paper towel.
• Water sticking to
your clothes.
Cohesive properties
• Cohesive
properties of
water
– Water molecules
sticking to itself
• Water beading up
on a waxed car.
• Rain droplets
• Surface tension.
Water and Life
Because of water’s unique properties many
chemical reactions occur in water which
allow and sustain life.
 Growth , development, energy, reproduction.
 Molecules can move throughout our cells.
Acids and Bases!
Everyday Acids
Properties of Acids
Erodes (Acid Rain) Dissolves (Stomach acid)
Burns (Battery
acid)
Tastes sour
Acids
•
•
An acid is a compound that releases
Hydrogen ions (H+) into solution.
HCL  H+ + CL– Hydrochloric acid  Hydrogen Ion + Chloride
Ion
•
A strong acid has a lot of H+ ions.
Everyday Bases
Properties of Bases
Feels Soapy or slippery
Tastes Bitter
Burns
Bases
• A base is a compound that release hydroxide
(OH-) ions into solution.
• NaOH  Na+ + OH– Sodium hydroxide  Sodium Ion + Hydroxide ion.
• A strong base has a lot of OH- ions.
Why are Acids and Bases important in
Biology?
•
Certain Biological reactions can only occur in acids
and bases.
–
–
•
Stomach acid dissolves food
Some digestion in the small intestine requires a base.
Acids and bases can also have an environmental
impact.
–
–
Dumping of chemicals into rivers, lakes and oceans.
Acid rain.
The pH Scale
• Acid strength is measured by the
concentration of H+ ions. This
concentration is called the pH.
The pH Scale
Neutralization
• Neutralization reaction - When a strong acid
and a strong base are mixed together.
– H+ + OH-  H2O
• A neutral substance has equal amounts of H+
and OH- when dissolved.
• A neutral substance has a pH of 7.
– Distilled water.
• Buffer: Keep pH in a particular range
Why are neutralization reactions
important in Biology?
•
Human Blood and cells must maintain a
pH of around 7.
•
•
Neutralization reactions help maintain a
constant pH.
Food going from the stomach to the small
intestine has a very high pH. The acid is
neutralized before entering the small
intestine.
Organic &
Inorganic
Compounds
Elements Found in Living Things
Most
of the atoms
found in living things
consist of
C, H, N, O, P, S
 96%
 Combinations
of these
make up most
compounds in living
things
Organic Compounds
 Organic
Compounds: are compounds which
contain carbon.
 Why is carbon so important?
 Carbon
has four electrons and can form a variety of
covalent bonds with other atoms.
 Carbon can form long chains.
 Carbon can form rings.
 Carbon can form single, double and triple bonds.
Organic Compounds
Organic Compounds can form
polymers.
 Smaller compounds called monomers
combine to form polymers.




This is similar to how we organize letters of
the alphabet to form a variety of words.
The letters are monomers and the words are
polymers
The joining of polymers is called
polymerization.
Organic Compounds
monomer
polymer
Inorganic Compounds



Inorganic Compounds do not
contain Carbon.
H2O, soil, calcium phosphate
(bones).
Exception  CO2
Compounds
of Life
Compounds of Life
Carbohydrates,
Lipids, Proteins
All
of these are
organic
compounds.
Carbohydrates
Examples
Starch
of carbohydrates
Table sugar
Fruit sugar
Carbohydrates
Carbohydrates
ENERGY!
are necessary for
Carbohydrates
 Carbohydrates
contain C, H, and O.
 The simplest form of a carbohydrate
is the monosaccharide (single
sugar).
 Glucose
– sugar produced by plants.
 Fructose – sugar found in fruits.
 Galactose – sugar found in milk.
Carbohydrates
Molecular formula = C6H12O6
•Glucose, Fructose and Galactose all
have the same molecular formula but
have different structures.
Carbohydrates
Combining
two monosaccharides
together forms a disaccharide
 sucrose
= glucose + fructose
 Maltose = glucose + glucose
 Lactose = glucose + galactose
Carbohydrates
Dehydration Synthesis
•A disaccharide is formed by dehydration
synthesis.
–Dehydration – loss of water
–Synthesis – put together.
Carbohydrates
When
many (more than two)
monosaccharides are joined together by
dehydration synthesis a polysaccharide is
formed.
A polysaccharide is good for storing excess
energy
Carbohydrates
•More than two glucose joined together forms the
polysaccharide starch in plants.
•Stores excess energy in plants
•Found in potatoes, pasta and rice
Carbohydrates
 More
than two
glucose joined
together forms the
polysaccharide
glycogen in animals.
 Stores
excess energy
in animals
 Found
in your
muscles and your
liver
Carbohydrates
A
polysaccharide can also be used for
structure.
Cellulose is found
in the cell wall of
plant cells
Chitin is found in
the exoskeleton of
many insects
Chitin is
found in the
cell wall of
fungus
Carbohydrates
•Disaccharides and
polysaccharides can be
broken apart by
Hydrolysis.
–The reverse of
dehydration synthesis.
–Add water to break
the bonds.
Lipids (Fats)
Lipids
 Cell
are necessary for
membranes, store energy, protect
organs, nervous system…..
Lipids (fats)
Examples
of lipids (fats)
Animal fat
Oil
Wax
Lipids (Fats)
•A lipid is made up of a glycerol and three
fatty acids.
•Formed by dehydration synthesis
•Broken apart by hydrolysis
Saturated Lipids
Animal
fat found in meat and dairy products.
Solid at room temperature.
 Due
to the single bonds.
 “Bad” fat. Too much can lead to heart disease.
Unsaturated & Polyunsaturated
Lipids
Unsaturated
 Contains
lipid
one or
more double
bonds.
 If there is more
then one double
bond it is called
polyunsaturated.
Unsaturated &
Polyunsaturated Lipids
Sesame,
peanut, corn and vegetable oil.
Liquid at room temperature.
 Due
to double bonds.
 “Good” fat.
Sterols & Phospholipids
Sterols and Phospholipds are important
to the structure and function of cells.
Sterols
 Steroid hormones
such as estrogen and
testosterone.
 Cholesterol – important part of the cell
membrane but too much can lead to heart
disease.
Sterols & Phospholipids
 Phospholipids
 Important to
the structure of the cell
membrane.
 One part dissolves in water, the other part
does not (How soap works! See the next
slide)
 Has a Hydrophilic (Polar) head - water loving
 Has a Hydrophobic (non-polar) tail - water
hating
Sterols & Phospholipids
A soap micelle
Dirt
Phospholipids
Proteins
 What
are some examples of
proteins?
 Hair,
nails, eyes, muscle,
enzymes.
 Proteins
have many
functions.
 Structure
(collagen in bones)
 Storage (Egg whites)
 Transport (cells)
 Enzymes (chemical reactions)
 Defense (immune system)
Proteins
Amino
Acid – Monomer of a protein.
-NH2
 Amino
group
-COOH
 Carboxyl
group
-R
 Variable
group (determines the type of
amino acid)
Proteins
 Proteins
are created by combining amino acids
through dehydration synthesis and broken down by
hydrolysis.
 Proteins are polymers of amino acids.
 The bond between two amino acids is called a
peptide bond.

Covalent bond
 Dipeptide
(two amino acids), polypeptide (many
amino acids)
Enzymes - A Type
of Protein
A
catalyst is a substance which
speeds up a reaction.
Our bodies use special catalysts
called enzymes.
Enzymes speed up the reactions
within our bodies.
 Dehydration
example.
Enzymes
synthesis and hydrolysis for
are proteins!
Enzymes - A Type of Protein
 Enzymes
are very specific.
 A particular enzyme will only speed up one
kind of reaction.
 Example:
Lactase – only breaks down lactose,
Sucrase digestion of sucrose.
 Example: Sucrase - only breaks down sucrose
 If
you are missing or don’t have enough of
an enzyme
 Your
body will not function properly.
 Examples: Lactose intolerance and Tay Sachs
disease.
Enzymes - A Type of Protein
Substrate
– The reactants.
Enzyme – Speeds up a reaction
Active site – Where the
substrate and enzyme bind
together.
Enzymes - A Type of Protein
Nucleic Acids
DNA
and RNA are used to transmit
genetic information.
Deoxyribonucleic acid and ribonucleic
acid
We’ll go over this when we cover more
about DNA