• Everything in the universe is made of matter.
• Matter is anything that occupies space and has
mass and is made of atoms!
• Mass is the measurement of the amount of
matter in an object.
Matter in our galaxy
• Elements are pure substances that
cannot be broken down chemically into
simpler kinds of matter.
(some things don’t count, for example:
protons, electrons, etc.)
• Many elements will be very familiar to you. For
• Others will not be familiar.
• For example… Einsteinium, Americium, Nobelium
• Over 100 elements have been identified
• 30 are important to living things
• 90% of the mass of living things are
composed of 4 elements
1. Oxygen (O)
2. Carbon (C)
3. Hydrogen (H)
4. Nitrogen (N)
• Elements have chemical
• Composed of one or two
• Usually taken from letters
in the common name.
• Sometimes taken from
Latin or Greek name
• Aurum (Au) for gold
• Natrium (Na) for
• Elements are also identified
by their atomic number.
• Elements are arranged in
the Periodic Table.
• The atom is the simplest particle of an
element that retains all of the properties
of that element.
• In other words, an atom is one single
“piece” of an element.
• For example, the smallest amount of
carbon = 1 atom of carbon
• Atoms are too small to be observed by
• Scientists show in model form
– Models do not show exactly what an
atom looks like.
– Used to predict how they will act
The atom is broken down into 2
1. Nucleus - contains protons
2. Electron cloud - contains
• The nucleus has 99.999% of the mass of an atom
but little volume
• Contains protons and neutrons
• Protons are positively (+) charged particles
• Neutrons are particles with no charge (0)
• All atoms of the SAME element have the SAME
number of protons.
• Atomic number = number of protons in the atom
• Mass Number = total number of protons and
neutrons in the atom
Atomic Mass or Mass Number
• Electrons have a negative charge (-)
• Very low mass, but high energy
• Electrons are NOT in the nucleus, but in the electron cloud
• The net electrical charge of an atom is zero (not positive or
negative) because the atom has an equal number of
electrons (-) and protons (+). The equal but opposite charges
cancel each other out.
• Number of Electrons = Number of Protons = Atomic
• Atoms can gain or lose electrons in chemical reactions and
become ions (more on this later)
• Isotopes are atoms of the same element
that have a different number of neutrons.
• The Average atomic mass of an element
takes into account the relative amounts of
each isotope in the element.
• Electron cloud
• We do not really know exactly where
the electrons are at any time in the
atom. We only know where they
• Fortunately, for most chemistry it
doesn't really matter where the
electron actually is, we only care
about how much energy it has.
• It’s convenient to think that electrons
move around the nucleus in orbits,
like the planets in the solar system.
• Orbitals may be misleading about
where an electron is, but they tell us
how much energy it has. We call this
the Energy Level of the electron.
• Bigger Orbit = Bigger Energy Level = Higher
• Energy levels can hold different numbers of
Level 1: 2 electrons
Level 2: 8 electrons
• The number of electrons in the outer energy level
determines the characteristics of the element.
• Energy Levels are usually not filled (except noble
• Goal: have outer energy level full
• Very few elements exist by themselves naturally, instead,
they are usually combined with other elements.
• 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 are usually very different from the
elements they form from
– Sodium – a reactive, soft , silvery metal
– Chlorine – a reactive, poisonous green gas
– Sodium chloride (or table salt) – stable,
• Most atoms are not stable in their natural state, so they
tend to react with other atoms in different ways to form
compounds and become more stable.
– Remember, the goal to stability is having a full outer energy level.
This is accomplished when atoms bond together to form
• Chemical bonds are the attractive forces that hold atoms
• Electrons from the outermost energy level of the atoms
are SHARED or TRANSFERRED whenever a bond is
• Covalent bonds are formed from atoms sharing
– Share 2 electrons (1 pair) = Single Covalent Bond
– Share 4 electrons (2 pairs) = Double Covalent Bond
– Share 6 electrons (3 pairs) = Triple Covalent Bond
• Usually occurs between two non-metal elements.
The animation above shows what happens in the formation of a covalent bond. The
individual atoms are atoms of chlorine with only their outer level of electrons shown.
Note that each chlorine atom has only seven outer electrons, but really wants eight.
• Ionic bonds involve the transfer of electrons
• When an atom gains or loses an electron it is
called and ion.
• Usually occurs between a metal and a nonmetal.
• Transferring electrons causes charges ( + or -) to
• Opposites attract and compounds are formed!
• Energy is defined as the ability to do
work and to cause change.
• There are many different forms of
1. Chemical Energy- stored in the bonds
of atoms and molecules. The food we
eat, natural gas, etc.
2. Thermal Energy- heat.
3. Electrical Energy- movement of
electrical charges, lightening, light.
4. Mechanical Energy- movement of
objects and substances from one
place to another.
• Energy is never created or destroyed, but it can
• A car engine burns gasoline, converting the chemical
energy in gasoline into mechanical energy and
• Scientists try to understand this FLOW of energy in
living systems and the universe.
• Living things depend on
• Chemical- food
• Thermal-your body
regulates your body
• Electrical- nerves use
electrical impulses to
to your brain
• Mechanical- moving your
• Atoms in all states of matter are constantly
moving. The RATE of this motion determines
the STATE of matter.
Least energetic, definite volume
Particles closely packed together,
vibrate, and have high attraction to
Definite volume, variable shape
(takes shape of container)
Has ability to flow, particles have
freedom to move
Takes volume and shape of container
Ability to flow, low attraction to each
Forms when a gas' temperature is raised to over
Its molecules collide so violently that the electrons are
knocked off the atoms.
Plasma is different from a gas because it is VERY hot
and is influenced by electric and magnetic fields.
Exists above the earth’s atmosphere
The influence of
magnetic fields on the
behavior of plasmas is
shown here by loop of
plasma on the sun
Gelatin is made of protein. Proteins are solids at most temperatures. When you mix
the Jell-O powder into the hot water, the protein dissolves in the water. As the
solution cools down, the protein comes out of solution and turns back into a solid.
But it doesn’t just form a solid that settles onto the bottom, the protein molecules
stick to each other forming a giant mixed-up jungle gym of protein molecules all
So, Jell-O is basically a solid suspended in a liquid. The scientific word for this is a
’colloid’. If you heat it up enough, the solid will become dissolved again, and it will
become a liquid all through. But, if you cool it down enough, the liquid water will
freeze, and it will become a solid all through.
• Energy needs to be added or
removed from system to change the
state of matter
• 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
• Living things perform thousands of chemical reactions
during life processes
• We write the reactions in equations
CH4 + 2 O2
CO2 + 2 H2O
• Broken down into two parts
1. Reactants – substances or molecules that
participate in a chemical reaction; found on left
side of an equation
2. Products – substances that form in a chemical
reaction; found on right side of an equation
• Atoms on each side of an equation have to equal in
number and type
• Your body is fueled by carbohydrates (sugar and starch),
proteins and fats!
• Body breaks them down into carbon dioxide and water in
a process called cellular respiration. This process
releases energy for your body to use.
Cellular Respiration: 6O2 + C6H12O6 --> 6H2O + 6CO2 + energy
• Plants absorb energy from the sun and combine it with
carbon dioxide and water to produce sugars and oxygen
Photosynthesis: 6CO2 + 6H2O + energy --> 6O2 + C6H12O6
• Metabolism - all of the chemical reactions that occur in an
• Activation Energy – the amount of
energy needed to start a chemical
• Catalysts – chemical substances that
reduce the amount of activation energy
that is needed for a reaction to begin
• Basically, by reducing the activation energy, catalysts
speed up reactions and cause reactions to occur.
Without them, reactions are very slow or never occur at
• Catalysts in living things are called enzymes
• Enzymes bind temporarily to one or more of the
reactants of the reaction. This lowers the amount of
activation energy needed and speeds up the reaction.
• Enzymes are VERY specific (a different enzyme for
– Ex. Sucrase catalyzes the breakdown of sucrose into glucose
• Enzymes – speed up reactions without being
permanently changed or destroyed
• Living things are mostly water
• Most reactions in living things occur in water solutions
• Water has several unique properties that make it one
of the most important compounds found in living things
• A solution is a mixture in which one or more
substances are dissolved in another
• Solvents and solutes make up solutions
1. Solute: part of a solution that is dissolved
2. Solvent: part of the solution that material is
dissolved in (coffee)
• Liquids, Solids, and Gases can
all be used in solutions.
Solutions can be solids
dissolved in liquids
Ex. Salt water
Solutions can be gases
dissolved in liquids
Ex. carbonated beverages
Solutions can be made from
Ex. Brass is a solution
containing copper and zinc
• Solutions can have varying amount of solute
dissolved in varying amounts of solvent
Concentration - A measurement of the
amount of solute dissolved in a fixed
amount of solvent
2% salt solution = 2g of salt in 100mL of
12% salt solution = 12g of salt in 100mL of
The more solute dissolved in solution, the
higher the concentration
Saturated solution - A solution where no
more solute can be dissolved in the solvent
• Aqueous solutions are solutions that have water as the
• Aqueous solutions are universally important to living
• Fish depend on oxygen dissolved in water to survive.
• Most nutrients plants need are in aqueous solutions in
• Body cells exist in an aqueous solution and are filled with
• Water is made of 2 hydrogen atoms and 1 oxygen atom (H20)
• They are covalently bonded so they share electrons.
• The oxygen is “greedy” and pulls the electrons closer to it.
The oxygen is therefore a little bit negative, and the
hydrogens are a little bit positive.
Because of this uneven distribution of charge, water is
called a polar molecule.
• 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.
• The polar nature of water
causes water molecules to
be attracted to one another.
• Opposites attract: the
oxygen of one molecule is
attracted to a hydrogen of
another. This attraction
results in a hydrogen bond.
• Hydrogen bonds in water exert an attractive force strong enough that water
“sticks” to itself and other substances!
Cohesion - An attractive force that holds molecules of a single
- Ex: water molecules stick to each other
Cohesion causes “surface tension” or a thin “skin” on the surface of
Adhesion - An attractive force between two particles of different
- Ex: water molecules stick to glass molecules
Adhesion causes capillarity, which results in the rise of the surface of a
liquid when in contact with a solid.
• Because of its hydrogen bonds, water has a high
heat capacity, which means that water can absorb
or release large amounts of energy in the form of
heat with only a slight change in its temperature.
• During a hot day, water can absorb heat (hydrogen
bonds break) and cool the air. At night, the water
cools (hydrogen bonds reform) and releases heat
into the air.
• Earth’s oceans stabilize global temperatures enough
for life to exist.
• Water’s high heat capacity allows your cells to keep
an even temperature despite changes in the
• Solid water is less
dense than liquid
– This is opposite of all
• Hydrogen bonding
causes ice crystals to
have large amounts
of open space.
• When bodies of water freeze, they freeze
from the top down and not the bottom up.
• Ice insulates the water below from the cold
air, which allows fish and other aquatic
animals to survive under the icy surface.
• The alkalinity or acidity of a solution can determine
the survival or death of organisms!
• What do we mean when we say acidic and alkaline
• Water molecules bump into each other and can actually break
each other apart! This results in a hydroxide and hydrogen ion.
• An ion is any atom(s) that have a positive or negative charge
– Hydroxide ion is the OH– Hydrogen ion is the H+
• The hydrogen ion (H+) can become attracted to the oxygen in
another water molecule resulting in a hydronium ion.
– Hydronium ion is the H3O+
• This process is called the ionization of water
• The relative concentrations of hydronium (H 3O+)
and hydroxide (OH-) ions in a solution
determines if it is an acid or a base.
• Pure water contains an equal number of both, so
it is a NEUTRAL solution.
• Some compounds, when they dissolve in water will
separate and form H+ ions. These compounds are called
• H+ will react with H20 to form H30+
– When HCl gas dissolves in water, it breaks up into H+
and Cl– H+ reacts with H20 to form H3O+. There is now more
H3O+ ions than OH- ions.
• There are always more H3O+ than OH- in acidic solutions.
Some common examples:
Hydrochloric Acid = HCl
Sulfuric Acid = H2SO4
Nitric Acid = HNO3
Acetic Acid = HCH3OO
Phosphoric Acid = H3PO4
• Called acidic
• Acids tend to taste sour
• Concentrated acids are very
– HCl in your stomach helps to
breakdown and digest proteins
• Examples: Orange juice, vinegar,
• Drinking acidic drinks over a long
period of time can erode the tooth
• Some compounds, when they dissolve in water and
separate will form OH- ions. These compounds are called
• When the solid NaOH dissolves in water, it
breaks up into Na+ and OH• There are now more OH- than H3O+ ions.
• There are always more OH- than H3O+ in basic
Some common examples:
Barium Hydroxide = Ba(OH)2
Sodium Hydroxide = NaOH
Potassium Hydroxide = KOH
Calcium Hydroxide =
• Called alkaline
• Slippery sensation when touched
– Bases react with oils in skin to form soap
• Bases have a bitter taste
• Examples: Soap, antacids (Magnesium hydroxide
and Aluminum hydroxide), ammonia
• Scientists have developed a
scale for comparing hydronium
and hydroxide ions in solution.
• pH scale
– Measures from 0 to 14
– Below 7 is acidic
– Above 7 is basic
– 7 is neutral
– Logarithmic scale (tenfold
change per number)
– pH of 4 is 100 times more
acidic (H3O+) than a pH of 6
How much more acidic is
vinegar compared to urine?
Difference of 3 pH levels =
10 x 10 x 10 = 1000 times
Acid + Base = A Neutral Solution (water and a salt)
• Living systems are very sensitive to
pH because enzymes can only
function in very specific pH ranges.
Uh oh, I think
we’re gonna be in
pH 4 soon!
But how will we
function? That is not
acidic enough, Help!
• Living things use buffers to prevent pH from
changing too much.
• Buffers are chemical substances that
neutralize small amounts of acids or bases in a
• Complex buffering systems keep you body’s
pH values at the right level.
• pH varies by body system
The pH of the human stomach is usually
between 2 and 3.
Ideally, the pH of the blood should be
maintained at 7.4. If the pH drops below 6.8
or rises above 7.8, death may occur.