Transcript Chapter 2 - A

Chapter 2
The Chemistry of Life
2.1 The Nature of Matter, 2-2
Properties of Water, 2-3 Carbon
Compounds, 2-4 Chemical
Reactions and Enzymes
2.1 The Nature of Matter
Key Concepts
What three subatomic particles make up
atoms?
How are all of the isotopes of an element
similar?
What are the two main types of chemical
bonds?
2-1 Atoms
The study of chemistry begins with the
basic unit of matter, the atom.
Atom
Incredibly small
If placed side by side, 100 million atoms would
make a row only about 1 centimeter long.
Contain subatomic particles
2.1 Atoms
The subatomic
particles that make
up atoms are
protons, neutrons,
and electrons.
http://www.youtube.
com/watch?v=pV82
2HfqT44
2.1 Atoms
Protons and neutrons have about the
same mass (or weight).
However, protons have a positive charge
and neutrons carry no charge or are
neutral. Very strong forces bind protons
and neutrons together to form the nucleus,
which is the center of the atom.
2.1 Atoms
Electrons are negatively charged
particles with are extremely small.
They are in constant motion. They are
attracted to the positively charged nucleus
but remain outside of it because of the
energy of their motion.
Because atoms have equal numbers of
electrons (-) and protons (+), and because
these subatomic particles have equal but
opposite charges, atoms are neutral
2.1 Element
A chemical element is a pure
substance that consists entirely of one
type of atom.
More than 100 known elements, but
only 24 are commonly found in living
organisms
Represented by one or two-letter
symbol
2.1 Element
Atomic Number- number of protons and
electrons in an atom
http://www.ptable.com/
2.1 Isotopes
Atoms of an element can have different
numbers of neutrons in their nucleus
Atoms of the same element that differ
in the number of neutrons they contain
are known as isotopes.
2.1 Isotopes
Mass Number- The
sum of the protons
and neutrons in the
nucleus of an atom
Isotopes are identified
by their mass numbers
Isotopes still have the
same number of
electrons and protons
They still have the
same chemical
properties
2.1 Radioactive Isotopes
Some isotopes are radioactive
Their nuclei are unstable and break down
at a constant rate over time
They give off radiation
2.1 Radioactive Isotopes
Scientific purposes for Radioactive
Isotopes
Geologists can determine the ages of
rocks and fossils by analyzing the isotopes
found in them
Radiometric Dating
Radiation from certain isotopes can be
used to treat cancer and kill bacteria that
cause food to spoil
Radiation
2.1 Radioactive Isotopes
http://www.youtube.com/watch?v=W_Cl
cBF6a0I&feature=related
2.1 Chemical Compounds
In the natural world, most elements are
found combined with other elements in
compounds.
Therefore, a compound is a substance
formed by the chemical combination of
two or more elements in definite
proportions.
2.1 Chemical Compounds
Scientists show the composition of
compounds by a kind of shorthand
known as a chemical formula
What is the chemical formula for water?
Carbon dioxide?
2.1 Chemical Compounds
The physical and chemical properties of
a compound are usually very different
from those of the elements from which
it is formed
Example
Hydrogen and oxygen, which are gases at
room temperature, can combine
explosively and form liquid water
2.1 Chemical Bonds
A chemical bond is an attraction between atoms that
allows the formation of chemical substances that
contain two or more atoms. The bond is caused by
the electromagnetic force attraction between
opposite charges, either between electrons and
nuclei.
There are two main kinds
Ionic Bonds
ions
Covalent Bonds
molecule
2.1 Chemical Bonds
Van der Waals forces- occur when
molecules are close together, and a
slight attraction can develop between
the oppositely charged regions of
nearby molecules.
Not nearly as strong as ionic or
covalent and can easily be broken
Hold large molecules together
2.1 Chemical Bonds
Gecko
Feet covered with half
a million tiny hairlike
projections that are
further divided into
hundreds of flat fibers
Van der waals forces
form between
molecules on the
surface of the gecko’s
foot and molecules on
the surface of the wall
2.2 Properties of Water
Key Concepts
Why are water molecules polar?
What are the properties of water?
What are acidic solutions?
What are basic solutions?
2.2 The Water Molecule
Like all molecules, a water molecule
(H2O) is neutral.
It has 10 protons (+) and 10 electrons (-)
that balance each other out
2.2 The Water Molecule
A water molecule is made of:
One oxygen atom that has 8 electrons and
protons
2 hydrogen atoms that each have one
electron and one proton
2.2 The Water Molecule
It has a bent shape
The oxygen atom at one end and the two
hydrogen's at the other end
As a result, the oxygen has a slightly
negative charge and the hydrogen's have
a slightly positive charge
A water molecule is polar because
there is an uneven distribution of
electrons between the oxygen and
hydrogen atoms
2.2 Hydrogen Bonds
Because of the positive and negative
charges of the water molecule,
hydrogen bonds occur
Hydrogen bonds are not nearly as
strong as covalent or ionic bonds
These hydrogen bonds are the reason
for:
Cohesion
Adhesion
2.2 Hydrogen Bonds
Cohesion- is an
attraction between
molecules of the
same substance
Water’s cohesion
causes molecules on
the surface of water
to be drawn inwards
Cohesion also
explains why some
insets and spiders
can walk on a pond’s
surface.
2.2 Hydrogen Bonds
Adhesion- is an attraction
between molecules of
different substances
Adhesion between water
and the chromatography
paper causes water to rise
in a narrow action.
In nature, you can see this
in plants. Capillary action
is one of the forces that
draws water out of roots of
a plant and up into its
stem and leaves
2.2 Solutions and Suspensions
Water is often found as a mixture, a
mixture is a material composed of two
or more elements or compounds that
are physically mixed together but not
chemically combined
2.2 Solutions and Suspensions
If you add sugar or salt to water, the
water eventually becomes a solution
A solution is a mixture where all the
components are evenly distributed
In a saltwater solution, the salt is the
solute (substance that is dissolved) and
the water is the solvent (substance in
which the solute is dissolved in)
2.2 Solutions and Suspensions
Some materials, such as oil, do not
dissolve when placed in water
Such mixtures of water and
nondissolved material are known as
suspensions, since the nondissolvable
particles separate and do not settle out
2.2 Acids, Bases, and pH
A water molecule can react to form
ions. This reaction can be summarized
by a chemical equation in which double
arrows are used to show that the
reaction can occur in either direction
Water
hydrogen ion
+
hydroxide ion
2.2 pH Scale
Chemists devised a measurement
system called the pH scale to indicate
the concentration of H+ ions in a
solution
pH scale ranges from 0-14
At a pH of 7 the concentration of H+ ions
and OH- ions is equal
Anything with a pH below 7 is considered
acidic because they have more H+ ions
Anything with a pH above 7 is considered
basic because they have more OH- ions
2.2 Acids and Bases
Acidic solutions
contain higher
concentrations of H+
ions than pure water
and have pH values
below 7
Strong acids are 1-3
Hydrochloric acid
(stomach acid)
ranges from 0-1.5
Basic solutions
contain lower
concentrations of H+
ions than pure water
and have pH values
above 7
Strong bases are
11-14
Oven cleaner and
bleach
2.2 Buffers
The pH of the fluids within most cells in
the human body must generally be kept
between 6.5 and 7.5.
If the pH is lower or higher, it will affect
the chemical reactions that take place
within cells
Buffers are weak acids or bases that
can react with strong acids or bases to
prevent sharp sudden changes in pH.
2.3 Carbon Compounds
Key Concepts
What are the functions of each group of
organic compounds?
2.3 The Chemistry of Carbon
One of the most abundant elements
Found in most inorganic compounds and ALL
organic compounds
Carbon forms strong covalent bonds
Carbon atoms can bond to other carbon
atoms
Carbon has the ability to form millions of
different large and complex structures
No other element can come close to matching
carbon’s versatility
2.3 Macromolecules
Many molecules in living cells are so
large that they are known as
macromolecules or “giant molecules”
Made from thousand of even smaller
molecules
Monomers-smaller units or single unit
Polymers-made of many monomers
Ex.// links on a watch, beads of a necklace
2.3 Macromolecules
It would be extremely difficult to study
the millions of organic compounds
(macromolecules) if they were not
classified into groups.
4 groups of organic compounds
Carbohydrates
Lipids
Nucleic acids
proteins
2.3 Carbohydrates
Made up of carbon, hydrogen, &
oxygen
Living things use carbohydrates as their
main source of energy. Plants and
some animals also use carbohydrates
for structural purposes.
Breakdown of sugars, such as glucose,
supplies immediate energy for all cell
activities
2.3 Carbohydrates
Single sugar molecules are also called
monosaccharides
Large molecules formed from
monosaccharides are known as
polysaccharides
Many animals store excess sugar in a
polysaccaride called glycogen (many
glucose molecules)
2.3 Lipids
Lipids are a large and varied group of
biological molecules that are generally
not soluable in water
Made of carbon and hydrogen atoms
Lipids can be used to store energy.
Some lipids are important parts of
biological membranes and waterproof
coverings
2.3 Lipids
Some lipids are fats,
oils, and waxes.
Steroids are lipids
as well
2.3 Nucleic Acids
Nucleic acids are macromolecules
containing hydrogen, oxygen, nitrogen,
carbon, and phosphorus
Nuclei acids are polymers made up of
monomers known as nucleotides
Three parts
5 carbon sugar
Phosphate
Nitrogenous base
2.3 Nucleic Acids
Nucleic Acids store
and transmit
hereditary, or
genetic information
2 kinds
RNA- ribonucleic
acid
DNAdeoxyribonucleic
acid
2.3 Proteins
Proteins are macromolecules that
contain nitrogen as well as carbon,
hydrogen, and oxygen
Proteins are polymers of molecules
called amino acids
2.3 Proteins
Some proteins control
the rate of reactions
and regulate cell
processes. Some are
used to form bones
and muscles. Others
transport substance
into or out of the cells
or help to fight
diseases.
2.4 Chemical Reactions &
Enzymes
All living things are made up of
chemical compounds
(macromolecules)- some are simple
some are complex. Everything that
happens in an organism- its growth, its
interaction with the environment, its
reproduction, and even its movement
are based on chemical reactions
2.3 Chemical Reactions
A chemical reaction is a process that
changes, or transforms, one set of
chemicals into another
Chemical reactions always involve
changes in the chemical bonds that join
atoms in compounds.
2.4 Chemical Reactions
Examples of chemical reactions:
CO2 + H2O
H2CO3
The reaction shown above enables the
bloodstream to carry carbon dioxide to the
lungs. In the lungs the reaction is reversed.
H2CO3
CO2 + H2O
This reverse reaction produces carbon dioxide
gas, which is released as you exhale.
2.4 Enzymes
Enzymes are proteins that can act as
biological catalysts in chemical reactions
Enzymes speed up chemical reactions that
take place in cells
http://www.youtube.com/watch?v=AEsQxzeA
ry8&feature=related
http://www.youtube.com/watch?v=qDEVBMld
iY8&feature=related
Sample Essay Questions
What are the 7 characteristics of life. List all
7 and explain each one. Include important
terminology/ vocabulary.
I am using a microscope that has an ocular
magnification of 10x, low objective of 10x,
medium objective of 40x, and high objective
of 100x.
What is the total magnification when I am using
the medium powered objective?
Show all work, including the equation.
Sample Essay Questions
Explain in 3 steps how to make a proper wet
mount of the letter “e”.
What are the two types of chemical bonds
you researched? What is the difference
between the two?
What are the 5 properties of water we
discussed in the H2O Fo Sho lab?
List all 5 then choose 2 and describe them.
Sample Essay Questions
In relation to carbon, there are 4 groups
of organic compounds
(macromolecules). List all 4 and
explain the functions of each one.
What happens to chemical bonds
during reactions? How are enzymes
related?
Other Test Info.
Make sure you are able to label the
parts of the microscope without a word
bank.
Know the difference in pictures
between SEM and TEM microscopes
Vocabulary Info.
Chapter 2 Vocabulary for Vocab portion of
the test
Atom
Isotope
Element
Covalent bond
Ionic bond
Cohesion
Adhesion
Acid
Base
Monomer
polymer
Monosaccharide
Polysaccharide
nucleotide
Carbohydrate
Lipid
Nucleic Acid
Protein
Enzyme