2. Chemistry
All living things depend on chemistry
◦ The structure and function of all living
things are governed by the laws of
chemistry
Why is it important to understand
chemistry in biology?
Biologists study chemistry because all
living things are made of the same
kinds of matter that make up nonliving
things
4. Matter
Everything in the universe is made of
matter
Matter is anything that occupies
space and has mass
Mass is the quantity of matter an
object has
5. Elements and Atoms
Elements are substances that cannot
be broken down chemically into
simpler kinds of matter
Information about elements is
summarized on a chart called the
periodic table
The simplest particle of an element
that retains all of the properties of that
element is an atom
7. The nucleus
Nucleus – the central region that
makes up the bulk of the mass of the
atom
◦ Consists of:
Protons – positively charged particles
Neutrons – particles with no charge
8. Electrons
Net electrical charge of an atom is
zero
Electrons – small, negatively charged
particles
◦ Move around the nucleus at very high
speeds
◦ Located in orbitals – regions around a
nucleus that show the probable location of
an electron
Orbitals correspond to specific energy levels
9. Elements
Atomic Number = number of protons
in an element
Mass Number = total number of
protons and neutrons in the atom
10. Isotopes
Atoms of the same element that have
a different number of neutrons
Average atomic mass of an element
takes into account the relative
amounts of each isotope in the
element
11. PRACTICE
In groups, we are going to practice
drawing elements on white boards
Group 1 – Draw and identify the
element that has 6 protons, 6
neutrons, and 6 electrons
Group 2 – Draw and identify the
element that has 7 protons, neutrons,
and electrons
12. PRACTICE
Group 3 – 8 protons, neutrons, and electrons
Group 4 – 15 protons, 16 neutrons, and 15
electrons
Group 5 – 16 protons, neutrons, and electrons
Group 6 – 11 protons, 12 neutrons, and 11
electrons
Group 7 – 13 protons, 14 neutrons, and 13
electrons
Group 8 – 19 protons, 20 neutrons, and 19
electrons
Group 9 – 26 protons, 29 neutrons, and 26
electrons
13. Compounds
Compounds are made up of atoms of
two or more elements in fixed
proportions
◦ Chemical formula shows the kinds and
proportions of atoms of each element that
forms a particular compound (Ex: H20)
Compounds usually very different from
the elements that form them
◦ Sodium – soft metal
◦ Chlorine – poisonous gas
◦ Sodium chloride – table salt
14. Compounds
Most atoms are not stable in their
natural state, so they tend to react
with other atoms in different ways to
become more stable
Chemical bonds are the attractive
forces that hold atoms together
15. Ionic Bonds Covalent Bonds
Formed when one or Formed when electrons
more electrons are are shared between
transferred from one atoms
atom to another ◦ Single, double, and triple
bonds
Ion – atom or molecule
with an electrical charge Molecule – simplest part
(Na+, Cl-) of a substance that
retains all of the
properties of that
substance and can exist
in a free state
Chemical Bonds
17. Energy
All living things use energy
Amount of energy in the universe
stays the same
Can change from one form to another
Transfer of energy is very important in
biology
18. Energy and Matter
Energy – the ability to do work
◦ Occurs in various forms and one form of
energy can be changed to another form
Important forms of energy in biological
systems
◦ Chemical, thermal, electrical, and
mechanical
19. States of Matter
The atoms and molecules in any
substance are in constant motion
The motion and spacing between
atoms or molecules determine the
substances state: solid, liquid, or gas
21. States of Matter
http://www.harcourtschool.com/activity
/states_of_matter/
22. Energy and Chemical
Reactions
Chemical Reaction – one or more
substances change to produce one or
more different substances
◦ Energy is absorbed or released when
chemical bonds are broken and new ones
are formed
◦ Living things undergo many thousands of
chemical reactions every day
23. Energy and Chemical
Reactions
Reactants –
substances or
molecules that
participate in a
chemical reaction
Products –
substances that
form in a chemical
reaction
24. Energy and Chemical
Reactions
Metabolism – the sum of all the
chemical reactions that occur in an
organism
◦ Energy your body needs is provided by
sugars, proteins, and fats found in foods
◦ Body continuously undergoes chemical
reactions to break down stored energy
from foods into substances your body can
use for energy
25. Activation Energy
Activation Energy – the amount of
energy needed to start a chemical
reaction
Catalysts – chemical substances that
reduce the amount of activation
energy that is needed for a reaction to
take place
◦ Enzymes – biological molecule that
speeds up metabolic reactions without
being permanently changed or destroyed
28. Water and Solutions
Chemical reactions of all living things
take place in the watery environment
of the cell
Water has several unique properties
that make it one of the most important
compounds found in living things
29. Polarity
Polar – compounds with an uneven
distribution of positive and negative
charges
30. Solubility of Water
The polar nature of water allows it to
dissolve polar substances, such as
sugars, ionic compounds, and some
proteins
Water does not dissolve nonpolar
substances such as fats like oil
32. Hydrogen Bonding
The polar nature of
water causes water
molecules to be
attracted to one
another
Hydrogen bond –
the force of
attraction between a
hydrogen molecule
with a partial positive
charge and another
atom or molecule
with a partial or full
negative charge
33. Cohesion Adhesion
An attractive force that An attractive force
holds molecules of a between two particles of
single substance different substances
together
Cohesion and Adhesion
34. Capillary Action
Attraction between
molecules that results in
the rise of the surface of
a liquid when in contact
with a solid
Cohesion and Adhesion
35. Questions
How are cohesion and adhesion
similar?
How are they different?
How do they contribute to capillarity?
36. Density of Ice
Solid water is less
dense than liquid
water
◦ This is opposite of
all other substances
Hydrogen bonding
causes ice crystals
to have large
amounts of open
space
37. Why is it important that ice is
less dense than water?
When bodies of water freeze, they
freeze from the top down
Ice insulates the water below from the
cold air, which allows fish and other
aquatic animals to survive under the
icy surface
38. Solutions
Solution – a mixture in which one or
more substances are uniformly
distributed in another substance
◦ Solute – substance dissolved in the
solvent (may be ions, atoms, or
molecules)
◦ Solvent – substance in which the solute
is dissolved
Sugar dissolved in water – which one
is the solvent and which is the solute?
39. Solutions
Solutions can be composed of various
proportions of a given solute in a given
solvent
Concentration of a solution is the
amount of solute dissolved in a fixed
amount of the solution
A saturated solution is one in which
no more solute can dissolve
41. Solutions
Aqueous solutions – solutions in
which water is the solvent
◦ Important to living things
Marine microorganisms spend their lives in the
sea
Most nutrients plants need are in aqueous
solutions in moist soil
Body cells exist in an aqueous solution and are
filled with aqueous solution
42. Important Properties of Water
Property What It Does/Means Importance
Cohesion Water molecules stick Movement of water in plants,
together surface tension
Adhesion Water sticks to another capillarity
substance
High heat Absorb and release large Stabilizes global temps, keep
capacity amounts of heat energy cells at even temps
without a big change in
temp
Solvent Water can dissolve many Marine organisms, plant
different substances nutrients, body cells
44. Ionization of Water
As water molecules move, they bump
into each other
Some of these collisions are strong
enough to result in a chemical change
One water molecule loses a proton
while another gains a proton
46. Ionization of Water
H3O+ : Hydronium Ion
OH- : Hydroxide Ion
Acidity or alkalinity is a measure of the
relative amounts of hydronium ions
and hydroxide ions dissolved in a
solution
47. Acids Bases
Number of hydronium Number of hydronium
ions (H3O+ ) GREATER ions (H3O+ ) LESS than
than the number of the number of hydroxide
hydroxide ions (OH-) ions (OH-)
Tend to have a sour taste Alkaline
Bitter taste
Acids and Bases
48. pH
pH scale – scale
for comparing the
relative
concentrations of
hydronium ions
and hydroxide ions
in a solution
Ranges from 0 to
14
Change in 1 pH
unit is a 10-fold
change in acidity or
alkalinity
49. Buffers
Buffers are chemical substances that
neutralize small amounts of either an
acid or a base added to a solution
Control of pH is important for living
systems
Enzymes can function only within a
very narrow pH range
