SNC2D – UNIT 1: CHEMISTRY REVIEW
CHAPTER 5 – CHEMICALS & THEIR PROPERTIES
PROPERTIES & CHANGES
 Properties are either chemical properties or physical properties
 Chemical properties describe the ability of a substance to form one or more
different substances.
 Physical properties describe a substance when it is not in the process of
forming a new substance.
PATTERNS AND THE PERIODIC TABLE
 Elements are arranged in the periodic table in order of atomic number
 Atomic number is the number of protons in the nucleus.
 Electrically neutral elements have the same number of electrons as protons
in each atom.
 Elements in vertical columns (groups or families) in the periodic table all
have the same number of electrons in their outer orbits.
 The number of electrons in the outer orbit (outer valence shell) affects the
reactivity of an element.
 Bohr-Rutherford Diagram vs. Lewis Dot Diagram (Lewis Dot diagrams are
more useful because they only show the outer electron configuration, which
helps us determine ionic charge.)
ATOMS & IONS
 Ions are atoms that have gained or lost electrons. Many ions have complete
outer orbits, so they are stable.
 Anions have more electrons than protons and therefore have a negative
charge. Anions have “ide” at the end of their names. Non-metals are typically
anions. Ex. Chloride is the ionic form of the element Chlorine.
 Cations have fewer electrons than protons and therefore have a positive
charge. Their name stays the same as their atom form. Metals are typically
cations.
 Atoms and ions can be represented by both Bohr-Rutherford and Lewis Dot
Diagrams
IONIC COMPOUNDS
 Elements (a metal and a non-metal) can react to form an ionic compound.
 During the reaction, the non-metal atoms pull electrons away from the metal
atoms.
 The ratio of metal ions to non-metal ions in an ionic compound depends on
the number of electrons each ion gains or loses.
 Most ionic compounds have high melting points and are hard, brittle
electrolytes
 Electrolytes dissolve in water to form solutions that conduct electricity.
NAMES & FORMULAS OF IONIC COMPOUNDS
 When writing chemical formulas of ionic compounds, the number of each ion
must balance the positive and negative charges so that the overall charge is
zero.
 The numbers of the ions in the chemical formula of an ionic compound must
be in the simplest ratio. The subscript “1” is not included in a chemical
formula. Ex. H2O is correct. H2O1 is incorrect.
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
The criss-cross method is used to write the chemical formulas for ionic
compounds. Ex.

Ionic compounds are named with the metal first and then the non-metal. The
ending of the non-metal’s name is changed to “ide”.
Some metals can form ions with different charges. In the name of an ionic
compound containing one of these metals, the charge is written as Roman
numerals in brackets after the name of the metal. Ex. Iron (III) or Iron (II).

POLYATOMIC IONS
 Polyatomic ions are made up of more than one atom, with a charge spread
over the entire ion.
 Polyatomic ions are present in many natural and artificial compounds. They
are used as food additives, fertilizers, and cleaners.
 Consider the polyatomic ion as a single unit when writing chemical formula
for a compound that includes a polyatomic ion. If the compound contains
more than one of the polyatomic, write curved brackets around the ion and
write a subscript outside the brackets.
MOLECULES AND COVALENT BONDING
 Molecular compounds both occur naturally and are produced synthetically.
Some are beneficial; others are not.
 Molecular compounds are made up of molecules. A molecule is a group of
two or more atoms joined by covalent bonds.
 A covalent bond forms when two non-metallic atoms share electrons.
 A variety of strategies are used to reduce the environmental damage
resulting from spilled chemicals.
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
The name of a molecular compound includes prefixes to indicate how many
atoms of each element are present (for example, dinitrogen pentoxide). If
there is only one atom of the first element, the prefix “mono” is omitted. The
name of the last element ends in “ide”.

Fossil fuels provide valuable energy and petrochemicals. Many important
industrial chemicals and consumer products are made from petrochemicals.
FORMULA WRITING GUIDE
Ionic Compound
 Determine the charges on each ion
(from either periodic table, or list of
polyatomic ions)
 Criss-cross the charges
 Reduce if possible
 Check your answer
Molecular Compound
 Determine how many bonds each
element will make (combining
capacity)
 Criss-cross the combining capacities
 Reduce if possible
 Check your answer
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NAMING COMPOUNDS GUIDE
Does the compound
involve a metal?
Yes
What is the other half
of the compound?
Are both non-metals
the same?
Polyatomic Ion
Non-Metal
Is the metal a
multivalent metal?
No
Yes
No
Write the name of
the metal, followed
by the name of the
non-metal, but
change the ending
to “ide”
No
Yes
Write the name of
the metal, followed
by the name of the
polyatomic ion
It’s a diatomic gas:
element “gas”
Use the prefix naming system: don’t
include mono for the first element
Write the name of the metal, write the
Roman Numeral indicating its charge,
write the name of the non-metal, but
change the ending to “ide”
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CHAPTER 6 – CHEMICALS & THEIR REACTIONS
DESCRIBING CHEMICAL REACTIONS
 Chemical reactions always involve one or more reactants changing to give
one or more products.
 State symbols are often written after a chemical formula to indicate the state
of a substance. Ex. (s) is solid, (l) is liquid, (g) is gas, (aq) is aqueous
 We can use word or chemical equations to describe a chemical reaction. In
both, the reactants are written on the left and an arrow point’s right, toward
the products.
 We use a + sign if there is more than one compound as a reactant or product.
CONSERVING MASS IN CHEMICAL REACTIONS
 Chemical equations contain information about which substances are
reactants and which are products, and the ratios of these substances.
 Chemical equations obey the law of conservations of mass.
 Coefficients can be added before chemical formulas in a chemical equation to
make the number of atoms in reactants and products balance.
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SUMMARIZED TABLE FOR TYPES OF REACTIONS
TYPES OF REACTIONS
REACTION
GENERAL EQUATION
Synthesis
X + Y  XY
Decomposition
XY  X + Y
Single Displacement
X + YZ  XZ + Y
Double Displacement
XW + YZ  XZ + YW
Complete Combustion of a
CXHY + O2  CO2 + H2O + Energy
Hydrocarbon
Incomplete Combustion of a
CXHY + O2  CO2 + H2O + CO + C +
Hydrocarbon
Energy
Combustion of Non-Hydrocarbons
XZ+ + O2  X2OZ + Energy
(Also a Synthesis Reaction)
Neutralization
Acid + Base  Water + Salt (Ionic
(Also a Double Displacement
Compound)
Reaction)
CORROSION
 Corrosion is the chemical breakdown of a metal as it reacts with chemicals in
the environment.
 Corrosion of some metals forms a tough protective layer that prevents
further corrosion.
 Rusting is the corrosion of iron and steel (which contains iron). Rust does not
form a protective layer but continues to flake away until the metal is severely
damaged.
 Rusting occurs in the presence of oxygen and water and is made worse by
electrolytes such as salt.
 Corrosion can be slowed or avoided by using corrosion-resistant materials,
covering the metal with a protective layer (for example, paint) or galvanizing
with thin layer of zinc.
CHAPTER 7 – ACIDS & BASES
PROPERTIES, NAMES, AND FORMULAS
 Acids are molecular compounds. In solutions, acids react with metals,
conduct electricity, and change the colours of acid-base indicators.
 Acids can be binary acids or oxyacids.
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LIST OF BINARY ACIDS
ACID NAME
Hydrofluoric acid
Hydrochloric acid
CHEMICAL FORMULA
HF (aq)
HCl (aq)
Hydrobromic acid
HBr (aq)
Hydrosulfuric acid
H2S (aq)
USE
Etching glass
Cleaning concrete
To make cleaning
compounds
Purifying metals
GENERAL WAY TO NAME A BINARY ACID
 Write “Hydro” and then the add the stem name of the second element.
 Replace of the second element with “ic”.
GENERAL WAY TO NAME AN OXYACID
 Drop the ending “ate” from the polyatomic name and replace it with “ic”.
 Add the word Acid after.
LIST OF OXYACIDS
ACID NAME
CHEMICAL
FORMULA
Acetic acid
Nitric acid
Carbonic acid
Sulfuric acid
Phosphoric acid
HC2H3O2 (aq)
HNO3 (aq)
H2CO3 (aq)
H2SO4 (aq)
H3PO4 (aq)
RELATED
POLYATOMIC
ION
C2H3O2- (aq)
NO3- (aq)
CO32- (aq)
SO42- (aq)
PO43- (aq)
POLYATOMIC
ION NAME
Acetate
Nitrate
Carbonate
Sulfate
Phosphate
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
Bases are ionic compounds. Many are hydroxides. In aqueous solutions, they
conduct electricity and change the colours of acid-base indicators.
Base Name
Sodium Hydroxide
Chemical Formula
NaOH (aq)
Calcium Hydroxide
Ca(OH)2 (aq)
Ammonium
Hydroxide
Magnesium
Hydroxide
Aluminum
Hydroxide
Sodium Hydrogen
Carbonate
(Baking Soda)

Uses
Making paper
Decreasing the acidity
of lakes and soil
NH4OH (aq)
Window Cleaners
Mg(OH)2 (aq)
Antacids
Al(OH)3 (aq)
NaHCO3 (aq)
Heartburn
medications
Making baked goods
rise and an abrasive
cleaner
Acid-base indicators show whether a solution is acidic or basic.
pH SCALE
 pH describes the acidity or basicity of a solution.
 The pH scale goes from 0 – 14.
 Solutions with a pH of 7 are neutral. The lower the pH, the more acidic the
solution. The higher the pH, the more basic the solution.
 Solutions that are highly basic or highly acidic are corrosive and reactive.
They must be handled with caution.
 Living things are sensitive to small pH changes in their environment.
ACID PRECIPITATION
 Acid precipitation is any precipitation is any precipitation that has a pH less
than the normal pH of rain.
 Acid precipitation is caused by pollutants (mostly SO2 from burning fossil
fuels and NOX from vehicle engines) reacting with water in the air to form
acids.
 Acid precipitation can have serious environmental and economic impacts.
 Steps taken to reduce the effects of acid precipitation include using lowSulfur fuels, adding scrubbers to smokestacks, installing catalytic converters
to vehicles, and enacting stricter anti-pollution laws.
 The production of pollutants is decreasing but is still causing damage in some
areas. Other areas are starting to recover.
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