Write the formula Metal (cation)first (roman) indicates metal charge Anion next, use first on PT for “ides” use half sheet for polyatomics Cation charge becomes anion subscript and vice versa(“criss-cross” charges) Reduce as necessary by greatest common factor

Sodium Chloride Na+ Cl- NaCl

Magnesium fluoride Mg 2+ F - MgF 2

calcium hydroxide Ca 2+ OH - Ca(OH) 2

Name a formula Metal (cation)first, just the name no prefix, no suffix IFF!!! PT shows more than one charge for the metal, Use (roman) to indicate metal charge Cation charge = (anion charge)X(anion subscript)/(cation subscript) Anion name next

Fe 3 (PO 4 ) 2 Iron Iron ( ) Iron ( ) Phosphate (3)x(2)/3=2 Iron (II) Phosphate Fe There’s two oxidation states, so we’ll need roman numerals. Anion charge is 3- Anion subscript is 2 Cation subscript is 3 Roman = 2

Parenthesis Use around polyatomics when there’s more than one in the molecule!