Molecules

• Molecule – two or more atoms covalently bound together

• Diatomic molecule – two of the same atom bound together

Diatomic Molecules

• Br I N Cl O F H or the Gang of 7 plus 1• These atoms never exist alone. They need a buddy• They always come in pairs• For example:

– Br Br2

– I I2

– N N2

– Cl Cl2– H H2

– O O2

– F F2

Binary Molecular Compounds

• Binary covalent compounds contain 2 nonmetals

• This is different from ionic compounds that contain a metal & nonmetal, metal & a polyatomic ion, or 2 polyatomic ions

Naming Binary Covalent Compounds

• Before you can name binary covalent compounds, you MUST know the prefixes!

Prefixes

• Mono• Di• Tri• Tetra• Penta• Hexa • Hepta• Octa • Nona• Deca

• 1• 2• 3• 4• 5• 6• 7• 8• 9• 10

Rules for Writing Covalent Compounds

1. Find the cation (nonmetal) and write down symbol

2. Look at the prefix and write it as a subscript after the symbol

3. Find the anion (nonmetal) and write down symbol

4. Look at the prefix and write it as a subscript after the symbol

*NO CHARGES

*NO REDUCING

*If there is no prefix, then it only a 1don’t write 1’s

Examples

1. Carbon dioxide

2. Phosphorus trifluoride

3. Nitrogen monobromide

4. Hexaselenium pentaiodide

5. Dicarbon monosulfide

• CO2

• PF3

• NBr

• Se6I5

• C2S

Naming Covalent Compounds

1. Name the prefix for # of atoms in the 1st element

-If the prefix is mono, drop it

2. Write the name for the 1st element

3. Name the prefix for the # of atoms in the 2nd element

4. Take the root name of the 2nd element and add “ide”

*NO CHARGES

Examples

1. SO2

2. N2F5

3. CO

4. S3Cl45. FI3

• Sulfur dioxide• Dinitrogen

pentafluroide• Carbon monoxide• Trisulfur

tetrachloride• Flurorine triiodide

Hydrates

• Some compounds trap water crystals when they form.

• These are hydrates.• Both the name and the formula needs to

indicate how many water molecules are trapped.

• In the name we add the word hydrate with a prefix that tells us how many water molecules.

Hydrates

• In the formula you put a dot and then write the number of molecules.

• Calcium chloride dihydrate = CaCl22

• Chromium (III) nitrate hexahydrate = Cr(NO3)3 6H2O

Acids

• Acids are in aqueous solution (aq)

• For the purposes of this class, we will assume that if it begins with H, we will name it according to the rules of naming acids

Remember…

ide hydro (root) + ic acid

ate (root) + ic acid

ite (root) + ous acid

Rule #1 - naming acids

• If the anion ends in –ide, the acid will be named…

• Hydro (root) – ic acid

• This is usually for H plus one element

For example

• HCl

• Hydrochloric acid

• HI

• Hydroiodic acid

• H2S

• Hydrosulfuric acid

Rule #2 – naming acids

• If you have an H plus an anion ending in –ate, the acid will be named…

• (root) – ic acid

Examples

• H2SO4

• Sulfuric acid

• HNO3

• Nitric acid

• H3PO4

• Phosphoric acid

Rule # 3 – naming acids

• If you have an H plus an anion ending in –ite, the acid will be named…

• (root) – ous acid

Examples

• H2SO3

• Sulfurous acid

• HNO2

• Nitrous acid

• H3PO3

• Phosphorous acid

Writing formulas for acids

• When writing formulas for acids you MUST look at the charges and bring them down!

Examples

• HBr

• Hydrogen + one element

• Hydrobromic acid

• HClO3

• H + chlorate

• ate ic

• Chloric acid

More examples

• H2SO3

• H2CO3

• HF• Nitrous acid• Perchloric acid• Iodic acid

• Sulfurous acid• Carbonic acid• Hydrofluoric acid

• HNO2

• HClO4

• HIO3

Mixed examples(remember to figure out what type of

compound it is 1st!)

• KClO2

• CO2

• H2SO4

• NH4Br

• CuCO3

• Fe2O3

• HClO

• Potassium chlorite• Carbon dioxide• Sulfuric acid• Ammonium bromide• Copper (II) carbonate• Iron (III) oxide• Hypochlorous acid

More Mixed Examples

• Carbon tetrachloride• Phosphorous pentachloride• Aluminum oxide• Copper (II) nitrate• Chlorous acid• Hydrophosphoric acid• Iron (III) hydroxide

• CCl4• PCl5• Al2O3

• Cu(NO3)2

• HClO2

• H3P

• Fe(OH)3