Identify the most common valency of an element and memorize the valencies of common polyatomic species
Predict the formula of binary compounds using valencies
Name a compound from its formula
Write the formula of a compound from its name
Valency
All elements have a valency (# of bonds they can make)
Groups 1, 2, 13, 14, 15, 16, and 17 have fixed valencies, with 14 having a valency of 4 and decreasing consecutively as you move away from 14 from left to right.
Al, Zn, and Ag have valencies of 3, 2, and 1, respectively.
All other metals have variable valency, so the nonmetal associated with the metal is used to determine the valency.
