3-6 Covalent Bonding (12.1) And you

“Co” = sharing and “valent” refers to valence electrons: covalent = sharing of one or more valence electrons between atoms. In the examples below, dots again represent valence electrons and a line represents 2 shared dots (single bond).

Examples H2 each H atom has 1 valence e- = 2e- s H. + H. = H:H CH4 each H has 1 e-, C has 4 = 8 e- s H. + H. + H. + H. + C = H H C H

H2O Each hydrogen has one e-, O has 6 e- = 8 e- H. + H. + O = H O H

3-7 Naming Covalent Compounds ~ Type/Class 3 Rules (Section 5.3) Class 3 rules involve covalent bonding, the sharing of valence electrons between 2 nonmetals. Since there are no charges for covalent bonding, prefixes are used to indicate the number of atoms. See location on periodic table please.

# Prefix 1 mono 2 di 3 tri 4 tetra 5 penta 6 hexa 7 hepta 8 octa 9 nona 10 deca

Names First element ~ use a prefix ONLY if the # of atoms is 2 or greater. Second element ~ ALWAYS needs a prefix and then “ide”.

Examples CO2 = Carbon dioxide CO = Carbon monoxide (note not mono oxide) N2O4 = Di nitrogen tetroxide (note not tetra oxide) BF3 = Boron tri fluoride

P4O6 = Tetra phosphorus hex oxide H2O = Di hydrogen mon oxide *** normally the prefix goes together with the atom i.e. monoxide. They are separate here to emphasize the process.

Formulas from names Look at the prefix for the number of atoms Sulfur dioxide = SO2 Sulfur trioxide = SO3 Sulfite (careful) = SO3-2 (this is a polyatomic ion)

Xenon tetrafluoride = XeF4 Tetraphosphorus decoxide = P4O10 Dioxygen difluoride = O2F2

Practice naming all types/classes Start by looking at where the first element is located on the periodic table. Keep in mind if it is in column 1a, 2a, or the 3 step region – use type 1 naming rules If it starts in the transition metal area, use type II naming rules (cation charge!) If it starts above the staircase, then type III rules (mono, di, tri...)

Fe(OH)3 Fe is in the transition metal area so type II Iron (III) hydroxide Al2S3 Al is in the 3 step region so type I Aluminum sulfide N2Cl4 Nitrogen is above the staircase so type III Dinitrogen tetrachloride

Sr(NO3)2 Sr is in group 2a so type 1 naming rules Strontium nitrate Ammonium carbonate Ammonium is a polyatomic ion with a +1 chg. NH4+ + CO3-2 = (NH4)2 CO3 Iron(II) phosphate Fe+2 + PO4-3 = Fe3(PO4)2 Silicon tetrabromide SiBr4

Lithium sulfate Li+ + SO4-2 = Li2SO4 Lithium sulfite Li+ + SO3-2 = Li2SO3 Lithium sulfide Li+ + S-2 = Li2S