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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