Midterm Review
Topic 2
Formulas and Equations
Vocabulary
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Chemical Change
Coefficient
Decomposition
Diatomic molecule
Double replacement
Empirical formula
Endothermic
Exothermic
Formula
Molecular formula
Molecule
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Physical change
Polyatomic ion
Product
Qualitative
Quantitative
Reactant
Single replacement
Subscript
Symbol
Synthesis
Chemical Symbols and Formulas
• Chemists have developed a universal language
by which they can communicate chemical
information and have the information
understood by scientists around the world
Diatomic Molecule
• BrINClHOF
Chemical Formulas
• Compounds are composed of combinations of
elements chemically combined in definite
proportions
– Formulas us chemical symbols and numbers to show
both qualitative and quantitative information about a
substance
– The chemical formula CO tells the reader that the
compound consists of Carbon and Oxygen.
– The chemical formula CO2 tell the reader that the
compound consists of 1 carbon and 2 oxygen atoms
Types of Formulas
• Empirical Formula
– Represents the simplest ratio in which atoms
combine to form a compound
• Molecular Formula
– Covalently bonded substances form discrete units
called molecules.
• In some cases, such as H2O, the chemical formula is
both empirical and molecular
• In other cases the molecular formula may be a multiple
of the empirical formula, for example glucose, C6H12O6
Atoms, Compounds, and Ions
• Ionic Charge
– The charge of an ion is
indicated by the superscript
following the symbol of the
ion.
– Al+3
• Polyatomic Ions
– A polyatomic Ion is a group of
atoms covalently bonded
together, possessing a charge
• Reference table E
Atoms, Compounds, and Ions
• Forming a Compound
– Compounds can be formed in several different
ways
• One way is the attraction of oppositely charged ions
• Monatomic or polyatomic ions attract each other in a
ration that produces a neutral compound
Atoms, Compounds, and Ions
• Coefficients
– The coefficient tells how many units of the
formula are present
Atoms, Compounds, and Ions
• Hydrates
– When water from come ionic solution evaporates,
the solute forms a crystal lattice that binds water
with in the structure
– CuSO4• 5H2O
Writing Formulas and Naming
Compounds
• Equalizing charges
– Compounds achieve neutrality by having an equal
number of positive and negative charges.
– When sodium ion (Na+1) and a chlorine ion (Cl-1)
combine, they will do so in a 1:1 ratio
– If you do not have a 1:1 ratio, they you must cross
down the charges
Writing Formulas and Naming
Compounds
• Naming Compounds
– Compounds are named according to the types of
elements that form them.
• Ionic compounds
– Binary or polyatomic
• Covalent compounds
– Binary or stock system
Chemical Reactions and
Equations
• Physical Change
– A change in state such as ice melting
• Chemical change
– The substances produced are quite different form
the starting material
Chemical Reactions and Equations
• Chemical Equations
Chemical Reactions and Equations
• Endothermic reaction
• Exothermic reaction
Chemical Reactions and Equations
• Balancing chemical equations
– Law of Conservation of Mass
Types of Chemical Reactions
• Synthesis
– A+B  AB
Types of Chemical Reactions
• Decomposition
– AB  A + B
Types of Chemical Reactions
• Single Replacement
– AB + C  AC + B
Types of Chemical Reactions
• Double Replacement
– AB + CD  AD + CB