How to Determine Ionic Charge?

Use the periodic table group number for main-group elements

Group 1 elements form +1 ions

Group 2 elements form +2 ions

Group 13 elements form +3 ions

Group 15 elements form -3 ions

Group 16 elements form -2 ions

Group 17 elements form -1 ions

Group 18 elements usually form 0 charge

Transition metals can have multiple charges

Determine transition-metal charge from the compound’s overall neutral charge

Use Roman numerals in names to identify transition-metal charge

Monatomic ions have charges based on electron loss or gain

Cations have positive charge

Anions have negative charge

Sum all ion charges in a compound to get the total charge

Use known common ion charges for polyatomic ions

Check the element’s valence electrons to predict charge

Metals tend to lose electrons

Nonmetals tend to gain electrons

Hydrogen is usually +1

Hydrogen is -1 in metal hydrides

Oxygen is usually -2

Fluorine is always -1 in compounds

Compare the ion’s charge to the number of electrons lost or gained