1. COMPOUNDS chemical combination of two or more different elements chemical combination of two or more different elements two types: two types: IONIC IONIC MOLECULAR MOLECULAR

2. CHEMICAL FORMULA shows the number and kinds of atoms in the smallest representative unit shows the number and kinds of atoms in the smallest representative unit for an ionic compound, it’s called the formula unit – lowest whole number ratio of ions for an ionic compound, it’s called the formula unit – lowest whole number ratio of ions

3. IONIC COMPOUNDS composed of cations (+) & anions (–) composed of cations (+) & anions (–) cation gives electrons cation gives electrons anion accepts electrons anion accepts electrons composed of metal + nonmetal composed of metal + nonmetal electrically neutral electrically neutral usually solid at room temp. usually solid at room temp.

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

5. NAMING IONIC COMPOUNDS metal (cation) comes first metal (cation) comes first nonmetal – ending changes to ‘-ide’ nonmetal – ending changes to ‘-ide’ lithium sulfide Li 2 S aluminum fluoride AlF 3 magnesium nitride Mg 3 N 2

6. WRITING FORMULAS FOR BINARY IONIC COMPOUNDS potassium chloride potassium chloride K + and Cl – K + and Cl – charge ratio 1:1 charge ratio 1:1 KCl KCl

7. calcium bromide calcium bromide Ca +2 and Br 1– Ca +2 and Br 1– charge ratio 2:1 charge ratio 2:1 CaBr 2 CaBr 2 WRITING FORMULAS FOR BINARY IONIC COMPOUNDS

8. Use criss-cross method charge on one ion becomes the subscript on the other charge on one ion becomes the subscript on the other REDUCE to lowest whole number ratio REDUCE to lowest whole number ratio WRITING FORMULAS FOR BINARY IONIC COMPOUNDS

9. Fe 3+ combines with O 2– WRITING FORMULAS FOR BINARY IONIC COMPOUNDS

10. Ca 2+ combines with S 2– WRITING FORMULAS FOR BINARY IONIC COMPOUNDS

11. FORMULAS AND NAMES write formulas: write formulas: Ba 2+, S 2– Ba 2+, S 2– Li +, O 2– Li +, O 2– Ca 2+, N 3– Ca 2+, N 3– Cu 2+, I – Cu 2+, I –

12. FORMULAS AND NAMES write formulas: sodium iodide gallium chloride potassium sulfide calcium iodide