BINARY MOLECULAR COMPOUNDS molecule: electrically neutral group of atoms that acts as a unit composed of nonmetals electrons are shared (covalent): NO CHARGES no criss-cross, no reducing subscripts can combine in more than one way

NAMING BINARY MOLECULES prefixes used to denote multiple atoms of one element in a molecule 1 mono- 6 hexa- 2 di- 7 hepta- 3 tri- 8 octa- 4 tetra- 9 nona- 5 penta- 10 deca-

NAMING BINARY MOLECULES 2nd element in name ends in –ide for oxides: if the prefix ends in a or o, LEAVE OUT the a or o monooxide becomes monoxide tetraoxide becomes tetroxide, etc.

NAMING BINARY MOLECULES if there is ONE atom of the first element, omit the prefix mono– ex: CO carbon monoxide NOT monocarbon monooxide

WRITING NAMES CO carbon monoxide CO2 carbon dioxide N2O dinitrogen monoxide Cl2O8 dichlorine octoxide

WRITING NAMES OF2 oxygen difluoride N2O5 dinitrogen pentoxide P4O10 tetraphosphorus decoxide SO3 sulfur trioxide

WRITING FORMULAS nitrogen trifluoride NF3 disulfur dichloride S2Cl2 dinitrogen tetroxide N2O4 carbon tetrachloride CCl4

DIATOMIC MOLECULES molecules with 2 atoms of the same element there are 7 – know them! N2 O2 H2 Cl2 I2 F2 Br2 or Br2 I2 N2 Cl2 H2 O2 F2

LEWIS DOT DIAGRAMS (ELECTRON DOT DIAGRAMS) show the valence electrons as dots inner electrons and atomic nuclei are represented by the symbol

LEWIS DOT DIAGRAMS (ELECTRON DOT DIAGRAMS) group 1A: 1 valence e- group 2A: 2 valence e-, etc.

LEWIS DOT DIAGRAMS (ELECTRON DOT DIAGRAMS) diatomic molecules

LEWIS STRUCTURES: STEPS 1. Count valence electrons and bonds using periodic table and octet rule – make a chart to get valence and shared electrons 2. Choose an arrangement of atoms (carbon in center, hydrogen or halogens on outside)

LEWIS STRUCTURES: STEPS 3. Put in calculated number of bonds; single bonds first, then multiple bonds if necessary. 4. Where necessary to complete octets, put in non-bonding electrons in pairs.

LEWIS STRUCTURES: STEPS 5. Check work by counting electrons in Lewis structure and comparing calculated number of valence electrons.

LEWIS STRUCTURES lO H–C–H CH2O V S C 4 4 H 1 1 O 6 2 12 8 / 2 = 4 bonds lO H–C–H

LEWIS STRUCTURES NH3 V S N 5 3 H 1 1 8 6 / 2 = 3 bonds H–N–H H

LEWIS STRUCTURES O–S–O O SO32– V S S 6 2 O 6 2 24 8 +2 -2 24 8 +2 -2 26 6 / 2 = 3 bonds O–S–O O 2-