A brief review
of
Chemistry
A few general terms…
 Anything that takes up space is
termed matter.
 An element is a substance that
cannot be broken down into simpler
substances.
Elements
• Elements are represented by a large letter (or letters)
(such as C, N, Na or O) on a large chart called the
periodic table.
Symbols you should memorize
(Quiz tomorrow)
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Carbon
Sulfur
Potassium
Nitrogen
Hydrogen
Phosphorus
Sodium
Iron
Oxygen
Clorine
Copper
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 The smallest
particle of an
element which
retains the
characteristics of
that element is
an atom.
On the diagram of an atom bellow, label the:
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Protons with an A
Electrons with a B
Neutrons with a C
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How many protons are there? _____
How man electrons are there? ____
How many neutrons are there? ____
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Using the periodic table, can you figure out what element
this is?
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Hint: Atomic number = the number of protons in the nucleus
 When two or more elements come
together to form a new product, the
process is called a chemical reaction.
 The resulting product, which is a new
combination of elements is called a
compound.
 Every compound has a unique
formula which shows how many
atoms of each are in the compound.
(eg. CO2)
 The smallest unit of a compound that
still retains the properties of the
compound is called a molecule.
Mixtures and Solutions
 Any two substances that are not
chemically combined but are together
is called a mixture.
 A solution is a class of mixtures in
which the molecules are evenly
distributed.
 The substance being dissolved is the
solute.
 The medium in which the substance is
being dissolved is called the solvent.
 Molecules that can be dissolved are
termed soluble.
 Molecules that cannot be dissolved are
termed insoluble.
Acids and Bases
 The pH scale measures
the acidity or basicity of
a substance.
 An indicator is a
chemical used to test for
pH.
 An acid or base usually
produces a color
change in the indicator.
 Electricity is also used
to measure pH.
http://www.fossweb.com/
Acids
 An acid has a high concentration of
dissolved H+ ions.
 It has a pH less than 7
 Some examples of acids are sulfuric
acid (H2SO4); hydrochloric acid (
HCl) and acetic acid (CH3COOH)
Bases
 A base has a high concentration of
OH- ions.
 It has a pH of more than 7.
 Some examples of bases are
ammonia (NH3) and acetate ion
(C2H3O2-).
Introduction to chemical
Reactions
 What does the word “chemical” mean
to you?
 Chemical: a single substance with
distinctive properties
 All matter is in the form of chemicals.
 A chemical always reacts the same way
under any given circumstance.
What is the difference between
a chemical change and a
physical change?
 Chemical Change: a new chemical is formed
 Examples: rusting, rotting, burning
 Signs of a chemical change – color change,
release of gas, new substance formed,
energy released
 Physical Change: NO new chemical is
formed
 Examples: breaking, dissolving, boiling,
evaporating, melting, eroding, freezing,
grinding, subliming
Indentify which of the following are
chemical (C) or physical (P) changes:
1.
2.
3.
4.
5.
6.
7.
8.
9.
a solid stretches when gently pulled ___
a powder dissolves in water __
a solid burns when ignited __
a liquid changes color when exposed to air for a long time __
a solid shatters into small pieces when hit with a hammer __
a gas “pops” when a burning match is placed close by __
solid becomes a gas when slightly warmed __
a liquid evaporates in hot weather __
limewater becomes cloudy when a gas passes through it __
 A chemical change is also called a “chemical
reaction.” How do we write a chemical reaction?
 Where are the “reactants” in an equation?
 Where are the “products” in an equation?
 What is the term for all the chemical reactions that
occur in an organism?
 Metabolism
Types of Reactions
 Synthesis reactions:
A +B
atoms, ions, or molecules
ANABOLISM

combine to form
AB
a new molecule
 Example: combining of amino acids to
form proteins
Types of Reactions
 Decomposition Reactions:
CATABOLISM
AB
Molecule breaks

apart to form
A+B
atoms, ions, or molecules
 Example: chemical digestion of food
particles into basic nutrients