1. Chapter 5 Section 3 Polyatomic Ions and Naming Compounds

2. Formulas for Ionic Compounds To write formulas for compounds you must remember that the molecule must be neutral. 1)Hydrogen (H +1 )oxidation # is +1 and Oxygen (O -2 )is -2 2) you need 2 (+1) to cancel out the – 2 3)So 2 Hydrogens are needed to match every Oxygen. (H 2 O) Criss-Cross Method

4. Polyatomic Ions Ions – elements that have lost/gained electrons Anions – ions have gained electrons & are negative(-) (+)Ca (+) ion-ions that have lost electrons and are positive (+) Polyatomic ions- multiple atoms hooked together that have +/- electrons

5. Polyatomic Ion Con’t Polyatomic ions are covalently bonded atoms that have either too many electrons between them or not enough and are placed in parentheses to show their charges. (OH) - =Hydroxide, (NH 4 ) + =Ammonium are some examples Subscripts tell # of atoms Superscripts tell # of electrons gained/lost

8. Naming Ionic Compounds Compounds are between Metals & Nonmetals. Metals are always listed 1 st & retain their name Non-metals are always listed 2 nd & their ending is changed to “ide” Sodium (metal)+ chlorine (nonmetal)= sodium chloride

9. Naming Covalent Compounds Use Numerical prefixes To: 1) show how many atoms of the first nonmetals there are in the compound 2) on the second non metal to show how many atoms there are, and change ending to -ide. ideN 2 O 4 = dinitrogen tetraoxide

10. TEST NO Ch. 5 TEST FRIDAY!!!

11. TEST Semester Final Thursday-19 th (1 st, 3 rd, 5 th ) Friday-20 th (2 nd, 4 th, 6 th )