Formula Review
• Ionic Formulas
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sodium oxide
lithium phosphate
ammonium sulfide
aluminum chloride
Formula Review
• Covalent formulas
• dinitrogen pentoxide
• carbon monoxide
• triphosphorous tetranitride
Chemical Reactions
• Examples of Chemical Reactions
– Gas stove burner
– Rust on a car
• How would a chemist describe these
reactions?
Word Equations
• Using the names of the substances, you
write a sentence describing the reaction
taking place
• Reactants (starting substances) are listed
first
• An action word (reacts, etc) or arrow
• Products (ending substances) are listed last
Writing Word Equations
• Gas stove burner
• Iron rusting
Chemical Equations
• Def’n - representation of a chemical
reaction
– Reactants on left
– Arrow
– Products on right
• Uses chemical symbols & formulas
Chemical Symbols & Fomulas
• Most elements are written as just symbols
• Exceptions (Br, H, O, N, Cl, I, F) are always
diatomic.
– Br2, H2, O2, N2, Cl2, I2, F2
• Make sure to correctly write & balance
charges on all ionic formulas!! (See flow
chart!!)
• NH3 = ammonia gas
Other Symbols
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+ - separate reactants or products
“yields”
used for reversable reactions
(s) - designates a solid
(l) - designates a liquid
(g) - designates a gas
(aq) - designates an aqueous solution
Symbols (Cont.)
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Indicates heat is supplied to the
reaction
•
Indicates a catalyst was used in
the reaction
– catalyst - speeds up the reaction, but is not
involved in the reaction
Writing Skeleton Equations
• Ethane gas reacts with oxygen to produce
carbon dioxide gas and water vapor
• Solid iron reacts with the oxygen in air to
produce solid iron (III) oxide
Demo #1
• Dihydrogen dioxide decomposes to form
water and oxygen gas
Demo #2
• Sodium metal reacts with water to form
dissolved sodium hydroxide and hydrogen
gas