Covalent Compounds

(c) McGraw Hill Ryerson 2007

• Covalent molecules share electronsshare electrons. Covalent bonds occur between two or more non-two or more non-

metals.metals. These molecules exist as solids, liquids or gases. Covalent molecules are like a play-pit full of plastic

balls. Each plastic ball =

1 covalent molecule of H2O

Water, H2O

See pages See pages 184 - 185184 - 185

(c) McGraw Hill Ryerson 2007

• The chemical formula of a covalent compound tells us the number of each element number of each element in the compound.– Sometimes the names don’t tell us what elements make up the compounds. – Subscripts mean something different in covalent compounds

• Ionic compounds subscripts show the smallest smallest whole-number ratio between the ions whole-number ratio between the ions in the compound.

• Covalent molecules have subscripts that show the actual number of actual number of atomsatoms in the molecule.

See page 193

Methane: CH4

Hydrogen Peroxide: H2O2 Water: H2O

(c) McGraw Hill Ryerson 2007 See page 193

What is the chemical formula for the molecule ethanol?

What is the name of the molecule C12O22H11?

C2H6O, a name that must be memorized or looked up when needed.

Sucrose, also called table sugar.

What is the chemical formula for candle wax? C25H52

(c) McGraw Hill Ryerson 2007

• Covalent compounds with 2 non-metal 2 non-metal atomsatoms use a system of prefixesprefixes.

See pages 194 - 195

Prefixes are often used before the atom name to indicate the number of atoms in the molecule.

Example: CO = carbon monoxide CO2 = carbon dioxide

CCl4 = carbon tetrachloride

(c) McGraw Hill Ryerson 2007 See pages 194 - 195

STEP 1: Write the most metallic atom (farthest left) first

STEP 2: Use prefixes to symbolize the # of each atom.

STEP 3: Add -ide to the end of the second atom’s name

(c) McGraw Hill Ryerson 2007 See pages 194 - 195

What is the chemical formula for the molecule trinitrogen tetrachloride?

What is the name of the molecule Si3P6?

N3Cl4

Trisilicon hexaphosphide

Covalent CompoundsWrite the names for the following covalent compounds: 1) P4S5 __________________________________ 2) SeF6 __________________________________ 3) Si2Br6 __________________________________ 4) SCl4 __________________________________ 5) B2Si __________________________________ 6) NF3 __________________________________

Covalent CompoundsWrite the formulas for the following covalent compounds: 1) antimony tribromide __________________________________ 2) hexaboron silicide __________________________________ 3) chlorine dioxide __________________________________ 4) iodine pentafluoride __________________________________ 5) dinitrogen trioxide __________________________________ 6) phosphorus triiodide __________________________________