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Chemistry of Life
Chapter 3
Pg. 48-73
Section 1: Matter and
Substances
Key Ideas:
What
Why
makes up matter?
do atoms form bonds?
What
are some important interactions between substances
in living things?
What is Matter???

Matter is anything that has mass and takes up
space.
Atoms

Atoms are the smallest units of matter that
still retain the properties of an element.
Atomic Structure
Particle
Location
Charge
Proton
Inside the
Nucleus
Positive (+)
Neutron
Inside the
Nucleus
No charge
(neutral)
Electron
Outside the
Nucleus
Negative (-)
Element

An element is a substance made up of atoms
that have the same number of protons.


Example: How many protons do all Carbon atoms
have?
Example: How many protons do all Magnesium
atoms have?
Element Configuration


Atomic Number - The
number of protons in the
nucleus of an atom
Atomic Mass Number Total number of protons
and neutrons
# of Neutrons =
Atomic #
Symbol
6
C
Atomic Mass # 12.011
Atomic Mass # - Atomic #
Electron Energy Levels
Electrons are located OUTSIDE of the
nucleus of an atom.
 Electrons are arranged
in different energy levels.





1st Level: 2 electrons
2nd Level: 8 electrons
3rd Level: 18 electrons
4th Level: 32 electrons
Valence Electrons

Valence electrons are those located in the
OUTERMOST energy level.

Example: This is called a Bohr Model of an atom.
It shows ALL the electrons in the atom.

Only the electrons on the outermost ring are the valence
electrons!!
Chemical Bonding

Chemical bonds form between atoms and hold
the atoms together.

Atoms are most stable (and happy) when they have
8 valence electrons.
Covalent Bonding

Covalent bonding is when atoms share valence
electrons.

Example: A molecule is a group of atoms joined
together by covalent bonds.
Water H20 is a covalent
compound

Ionic Bonding

Ionic bonding occurs when atoms gain or lose
electrons in order to have 8 valence
electrons.
Ion- an atom that
has a positive or
negative charge
because it lost or
gained electrons.
 Example:
 Sodium + Chlorine

Polarity

In covalent bonds, the shared electrons are
attracted more to one atom than the other.
One end, or “pole” has a negative
charge and the other end has a
positive charge.
 Water is polar:

Solubility
Water can dissolve polar molecules, like sugar
and salt.
 Non-polar substances, like oil, grease, and wax
do NOT dissolve in water.


The reason: water molecules are more attracted
to themselves than to the non-polar molecules.
Section 2: Water and
Solutions
Key Ideas:
What
How
makes water a unique substance?
does the presence of substances dissolved
in water affect the properties of water?
Properties of Water
Most of the unique properties of water result
because water molecules form hydrogen
bonds with each other!
 1. Ice floats- water is less dense as a solid
than as a liquid!

Continued…Properties of Water

2. Water absorbs and retains heat.
Water can absorb large amounts of heat without
changing temperature.
 Water takes a long time to cool.
 Large bodies of
water (oceans/lakes)
not heating up or
cooling too quickly
keeps temperatures
on earth from
changing too fast.

Continued…Properties of Water
 3.
Water molecules stick to each
other!
 Hydrogen bonds hold water
molecules together.
 When you see a water drop, it looks
like a ball because the molecules
stick together!
 Cohesion is the attraction of
particles of the same substance.
Continued…Properties of Water

4. Water molecules stick to other polar
substances (called adhesion!)
Solutions

Solution is a mixture in which ions or
molecules of one or more substances are
evenly distributed in another substance.

Example: Dissolving salt in water makes a salt
water solution. The salt is dissolved evenly
throughout the water.
Acids and Bases
Acids- have a pH of 7 and lower (H30+ ions)
 Bases-have a pH of 7 and higher (OH- ions)



Water: pH is 7 (neutral)
Acid + Base = water!!!
pH and Buffers
pH is a measure of how acidic or
basic a solution is.

pH of human blood is 7.4……if
the pH goes too high (7.8) or
too low (7.0) a human will die
within minutes!!!

A buffer is a substance
that prevents pH changes
in a solution.

Section 3: Carbon
Compounds
Key Ideas:
What are chemicals of life made from?
What is the role of carbohydrates in cells?
What do lipids do?
What determines the functions of proteins?
What do nucleic acids do?
Biomolecules
Biomolecules are the building blocks of cells
 Basic units of biomolecules are atoms of
carbon.

4 Biomolecules of Living
Organisms

1. Carbohydrates

2. Lipids

3. Proteins

4. Nucleic Acids
Carbohydrates


Stores energy and provides shape to organisms
Starch


Cellulose



Potatoes & Plants
One of the most abundant carbohydrates
Makes up materials such as pencils, paper, and desks
Sugars



Mono-saccharide – Easily broken down for quick energy
(Candy bar)
Di-saccharide- Two sugars (example table sugar)
Polysaccharide – Combination of mono & disaccharide’s
(starch)
Lipids
Longer energy storage
 Include fats, oils, steroids, and waxes
 Functions in adaptation




Human Hormones
Keeps whales warm
Wax keeps fruit dry
Proteins
Proteins are molecules
made of amino acids.

There are 20 possible
amino acids that join
together in different
combinations to form
many different proteins.


Protein uses:
Hair, skin, nails,
ligaments, muscles,

Nucleic Acids