2.5 notes: binary and binary ionic compounds

compound: two or more elements chemically bonded together to form molecules or formula units
* binary ionic compound: a compound consisting of one metal and one nonmetal chemically bonded to form formula units, not molecules
two types of metals
  * monovalent metals—only one charge possible
    * alkali metals (+1 charge), alkaline earth metals (+2), aluminum (+3), zinc (+2), and silver (+1)
  * multivalent metals—multiple charges possible
    * transition metals (center of the periodic table)

naming rules

name the metal first, and written as it appears on the periodic table
change the ending of the nonmetal to -IDE
if the metal is multivalent, use a roman numeral to specify the charge on the metal cation. if the metal is monovalent, the charge is not specified with a roman numeral
* eg. NaCl = sodium chloride (sodium is monovalent)
* eg. CuO = copper (II) oxide (copper is multivalent)
the charges of each element must add to 0

binary ionic formulas

the positive ion (the metal) is always written first in a formula
the sum of the charges must equal zero—the total positive charge on the positive ion(s) must equal the total negative charge on the negative ion(s)
use subscripts if more than one ion is needed