COMPOUNDSCOMPOUNDS chemical combination of two or chemical combination of two or

more different elementsmore different elements two types:two types:

IONICIONICMOLECULARMOLECULAR

CHEMICAL FORMULACHEMICAL FORMULA shows the number and kinds of atoms shows the number and kinds of atoms

in the smallest representative unitin the smallest representative unit for an ionic compound, it’s called the for an ionic compound, it’s called the

formula unit – lowest whole number formula unit – lowest whole number ratio of ionsratio of ions

IONIC COMPOUNDSIONIC COMPOUNDS composed of cations (+) & anions (–)composed of cations (+) & anions (–)

cation gives electronscation gives electronsanion accepts electronsanion accepts electrons

composed of metal + nonmetalcomposed of metal + nonmetal electrically neutralelectrically neutral usually solid at room temp.usually solid at room temp.

BINARY IONIC COMPOUNDSBINARY IONIC COMPOUNDS binary – composed of 2 elementsbinary – composed of 2 elements (+) must balance (–)(+) must balance (–) net charge = 0net charge = 0

NAMING IONIC COMPOUNDSNAMING IONIC COMPOUNDS metal (cation) comes firstmetal (cation) comes first nonmetal – ending changes to ‘-ide’nonmetal – ending changes to ‘-ide’

lithium sulfidelithium sulfideLiLi22SS

aluminum fluoridealuminum fluorideAlFAlF33

magnesium nitridemagnesium nitrideMgMg33NN22

WRITING FORMULAS FOR WRITING FORMULAS FOR BINARY IONIC COMPOUNDSBINARY IONIC COMPOUNDS

potassium chloridepotassium chlorideKK++ and Cl and Cl––charge ratio 1:1charge ratio 1:1KClKCl

calcium bromidecalcium bromideCaCa+2+2 and Br and Br1–1–

charge ratio 2:1charge ratio 2:1CaBrCaBr22

WRITING FORMULAS FOR WRITING FORMULAS FOR BINARY IONIC COMPOUNDSBINARY IONIC COMPOUNDS

Use criss-cross methodUse criss-cross method charge on one ion becomes the charge on one ion becomes the

subscript on the othersubscript on the other REDUCE to lowest whole number REDUCE to lowest whole number

ratioratio

WRITING FORMULAS FOR WRITING FORMULAS FOR BINARY IONIC COMPOUNDSBINARY IONIC COMPOUNDS

FeFe3+3+ combines with O combines with O2–2–

WRITING FORMULAS FOR WRITING FORMULAS FOR BINARY IONIC COMPOUNDSBINARY IONIC COMPOUNDS

CaCa2+2+ combines with S combines with S22––

WRITING FORMULAS FOR WRITING FORMULAS FOR BINARY IONIC COMPOUNDSBINARY IONIC COMPOUNDS

FORMULAS AND NAMESFORMULAS AND NAMES write formulas:write formulas:

BaBa2+2+, S, S22––

LiLi++, O, O22––

CaCa2+2+, N, N33––

CuCu2+2+, I, I––

FORMULAS AND NAMESFORMULAS AND NAMES write formulas:write formulas:

sodium iodidesodium iodidegallium chloridegallium chloridepotassium sulfidepotassium sulfidecalcium iodidecalcium iodide