1. Chemical Equation Writing

2. Writing Equations 1) Word Equations (ex) methane + oxygen -----> carbon dioxide + water - states the name(s) of the reactants (what you start with = left side of arrow) and the name(s) of the products (what you end with = right side of arrow). - does not state quanity!!!

3. 2) Chemical equation (ex) CH 4 (g) + 2O 2 (g) -----> CO 2 (g) + 2H 2 O (l) - states reactants and products - states quantities!!! - the letters in parentheses indicate the physical state of each substance involved: (g) = gas (l) = liquid (s) = solid (aq) = aqueous = dissolved in water (cr) = crystalline solid

4. - the coefficient (large number out front) tells us: 1) number of moles 2) number of molecules 3) volume iff a gas and STP (standard T & P) 4) number of atoms when mult. by the subscript. - when writing a chemical equation the Law of Conservation of Atoms must be obeyed! - Law of Conservation of Atoms: - the total number of atoms of reactants must equal the total number of atoms of products.

5. ***** NOTE: When the following elements are standing alone they combine with themselves in order to become stable (in the following manner): - H 2, I 2, N 2, Cl 2, Br 2, O 2, F 2 - P 4 - S 8

6. Types of Reactions 1) Binary Composition: - occur when 2 elements combine to form a binary compound. general form: element + element -----> binary compound X 0 + Y 0 -----> XY - elements that stand alone have an oxidation state of zero! - compound’s name will end in -ide (binary) - use the lowest oxidation state for the metal unless: 1) metal = Cu 2+ 2) metal = Hg 2+ 3) or there is an excess of the nonmetal

7. (ex) lithium + bromine -----> lithium + bromine -----> lithium bromide Li + Br2 -----> LiBr 2Li + Br2 -----> 2LiBr (ex) iron + sulfur -----> iron + sulfur -----> iron (II) sulfide Fe + S8 -----> FeS 8Fe + S8 -----> 8FeS (ex) copper + oxygen -----> copper + oxygen -----> copper (II) oxide Cu + O2 -----> CuO 2Cu + O2 -----> 2CuO