Biochemistry

Life depends on
chemistry.

Living things are composed of
chemical compounds.

In order to
understand

biology, one must
first understand
the chemistry of

Fill in the Blank

Life is all about ___(9)____

The Atom

1. An atom is the basic unit of matter.

2. The atom is the smallest particle of a

substance that still retains the
properties of that substance.

3. Atoms are composed of subatomic particles:

Protons, neutrons, and electrons.

4. Protons and neutrons have about the same mass and

together form the nucleus of the atom.

5. Electrons have a mass of about

1/1840ththe mass of a proton and
are in constant motion in the
space surrounding the nucleus.

Multiple Choice

All matter is made of _________.

• energy 
• atoms 
• electrons 
• compounds 

The subatomic particles

have charges:

Protons have a
positive charge.

Electrons have

a negative

charge.

Neutrons have no charge.

Match

Match the following

• Protons

• Electrons

• Neutrons

Positive Charge

Negative Charge

No Charge

• Positive Charge

• Negative Charge

• No Charge

Elements

An element is a pure
substance consisting
of all the same type of
atom.

There are more than 100
known elements, but
only about 20-24 are
commonly found in
living organisms.

Compounds

A compound is

the

chemical

combination of two

or more elements in

definite

proportions.

For example: The formula of
water is H2O. There are 2
hydrogen atoms bonded to
one oxygen. This definite
ratio is always present in
water.

Chemical Bonds

The atoms that compose compounds
are held together by chemical bonds.

Bond formation
always involves the
_________ that
surround the nucleus
of each atom.

electrons

There are two main
types of bonds:

Ionic

Covalent

Multiple Choice

Whether ionic or covalent...atoms bonds through their...

• protons

• neutrons

• electrons

An ionic bond is formed when
one or more electrons are:

transferred from one atom to
another.

When electrons are
gained or lost, ions
are formed. Ions are

atoms that have

either gained or lost

electrons.

If an atom loses electrons, it will
then have a ________ charge.

positive

If an atom gains
electrons, it will

then have
a_______
charge.
negative

An ionic bond is formed
when ….

…. ions of opposite charges
are attracted to one another.

For example: Sodium tends to
lose an electron and becomes a
Na+ion. Chlorine tends to gain
one electron and becomes a Cl–
ion. These two ions are then
attracted to one another because
they have opposite charges. The
compound NaCl is formed.

The attraction between
oppositely charged
ions is an ionic bond.

Drag and Drop

In ionic bonding elements either gain or lose​

Placeholder

Drag these tiles and drop them in the correct blank above

electrons

protrons

neutrons

Covalent Bonds

Sometimes electrons

are

_________

between atoms

instead of being

transferred.

shared

When electrons are shared between
two atoms, the shared electron
spends time traveling around the
nuclei of both atoms.

A covalent bond is formed when

electrons are shared between atoms.

For example: In a
water molecule, each
hydrogen atom shares
electrons with the
oxygen atom.

The shared electrons spend part of the time
traveling around the _________ nucleus and part of
the time traveling around the _______ nucleus.

hydrogen

oxygen

When atoms are joined together by covalent bonds,
__________ are formed. A molecule is the smallest
unit of a compound.
molecules

Multiple Choice

Ionic or covalent?
C  O

• Ionic
• Covalent

Multiple Choice

Ionic or covalent?
H  H

• Ionic
• Covalent

Multiple Choice

Ionic or covalent?
K  Br

• Ionic
• Covalent

Multiple Choice

Ionic or covalent?
H  O

• Ionic
• Covalent

Multiple Choice

Ionic or covalent?
Na  Cl

• Ionic
• Covalent

Multiple Choice

Ionic or covalent?
C  H

• Ionic
• Covalent

Multiple Choice

Ionic or covalent?
Ca  Cl

• Ionic
• Covalent

Polar

Molecules

North Pole
South Pole

Polar molecules

don’t have anything

to do with cold

temperatures, but
these molecules do
have opposite ends

…. Or poles!

When covalent
bonds are formed
between atoms of
different elements,
there are different
degrees of ….

… attraction for
the shared
electrons.

In covalent bonds
formed between
atoms of different
elements, the
electrons are not ….

….shared equally
between the atoms
involved.

Some atoms have a
stronger attraction for
electrons than do
other atoms. As a
result, the electrons
are not shared equally.

The atom around which the
electrons spend the most time will
have a _______________ charge,
and the atom around which the
electrons spend the least time will
have a ______________ charge.

slightly negative

slightly positive

Polar

Covalent
Bonds:

Covalent bonds

in which

electrons are

shared

unequally

resulting in a

molecule which
has poles -- part
of it is negative
and part of it is

positive.

In a water molecule, oxygen has a _________________
for the shared electrons. The shared electrons spend
more time around the ________ atom, so the oxygen
atom has a ______________ charge.

stronger attraction

oxygen

slightly negative

Oxygen

− −

The shared
electrons spend
less time around
the ________
atom, so the
hydrogen atom
has a ___________
charge.

hydrogen

slight positive

Hydrogen

Hydrogen

+ +

A water molecule is: polar because one
end is positive and one end is negative.

Nonpolar Covalent Bond: The electrons
are shared _______. These bonds exist
between identical atoms such as H2, Cl2,

O2, and N2.

equally

O O

Water – We Can’t Have Life Without it!

The polarity of water is so important!
Let me say this one more time!!

In a water molecule, an oxygen atom has a much
_________________ for electrons than does the
hydrogen atom. At any given time, there is a greater
probability of finding the shared electrons near the
_________ atom than near the ___________ atom.

stronger attraction

oxygen

hydrogen

As a result, the oxygen end of the molecule has a slight negative
charge and the hydrogen end of the molecule has a slight positive charge.

A molecule that is positive at one end
and negative at the other end is called

a polar molecule.

A water molecule is polar because
there is an uneven distribution of
electrons between the oxygen and

hydrogen atoms.

Hydrogen Bonding

Water molecules
stick together
because the
opposite charges
of the molecules
attract one
another.

<----- Water

molecule

<------ Hydrogen Bond

This force of attraction
forms hydrogen bonds.

The attraction

between the oxygen

of one water

molecule and the

hydrogen of a
different water

molecule

forms a hydrogen

bond.

A single water molecule can form up to 4 hydrogen bonds with
other water molecules are the same time. This is responsible for
many of the unusual properties found in water.

Multiple Choice

Hydrogen Bonds typically occur between atoms of hydrogen involved in this type of bond:

• Ionic

• Nonpolar Covalent

• Polar Covalent

• Nonpolar AND Polar Covalent

Fill in the Blank

Hydrogen bonds are VERY important in determining the many properties of this very important molecule

I am finally getting to the point!!
Let me tell you about cohesion

and adhesion!

Cohesion is: The attraction between molecules of the same

substance.

Water molecules stick to one another
because of cohesion.

Adhesion is:

an attraction between
molecules of different

substances.

When water sticks to
other substances beside
itself, it does so because
of adhesion.

Solutions

and

Suspensions

Mixture:

A substance
composed of two
or more elements
or compounds that
are physically
mixed together but
are not chemically
combined.
Homogeneous

Mixtures:

The parts of the mixture
are very evenly mixed.

Heterogeneous Mixture

The parts of the
mixture are
unevenly mixed
such as in oil
mixed with water.

Multiple Choice

A _________ is made up of two or more substances that are together in the same place but ARE NOT chemically combined.

• Pure substance

• Mixture

• Solution

• Suspension

Multiple Choice

Suspensions are ___________ mixtures.

• Homogenous

• Solid

• Common

• Heterogeneous

Multiple Select

Identify which images are PURE SUBSTANCES! (Check all that apply) : )

Multiple Choice

Solutions are ___________ mixtures.

• Solid

• Homogenous

• Heterogeneous

• Gas

Suspension:

A mixture of
water and
undissolved

materials

Some materials do not dissolve in
water, but separate into pieces so
small that they do not settle out.
These small pieces remain
undissolved and are “suspended” in
the solution.

Example:

Your blood is a

suspension.

Water Makes Life on Earth Possible

Without water, life on Earth
would not be possible.
Here are the reasons why
life on Earth is dependent
on water.

Water is ________. This means that
water molecules like to _____
________. At a wide range of
temperatures, this sticking together
of water molecules makes water
______. If the temperature gets too
high, ______________ are broken
and water molecules will
_____________________________.

cohesive

stick

together

liquid

hydrogen bonds

escape into the atmosphere as a gas

Acids, Bases, and pH

The pH scale

The pH scale is a measurement system
used to indicate the concentration of H+

ions in a solution.

The pH scales ranges from

_________.
0 to 14

A pH of 7 is a _________ solution.
This is neither acidic nor basic. Pure
water has a pH of 7.

neutral

Solutions with a pH below
7 are considered ______.

acidic

Solutions with a pH above 7
are considered ______.

basic

Acid:

Any compound that forms
H+ions in a solution.

Acidic

Solutions:

Have a greater H+
ion concentration
that pure water.

Acids have a pH of below 7.

Examples include:
lemon juice, tomato
juice, carbonated
drinks, vinegar

Base: Any compound that forms OH–ions in a solution

Basic Solutions: Have a lower H+ ion concentration than pure water

Bases

have a pH
of above 7

Examples include: ammonia, soaps, bleach,

sodium bicarbonate.

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Did I cover that to fast (cause I did...but that is why you are taking CHEM next your) cause you have all year next year to learn this.