Molecules Molecule two or more atoms covalently bound

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 2 I I 2 N N 2 Cl 2 H H 2 O O 2 F F 2

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 its only a 1 don’t write 1’s

Examples 1. Carbon dioxide 2. Phosphorus trifluoride 3. Nitrogen monobromide 4. Hexaselenium pentaiodide 5. Dicarbon monosulfide • • • CO 2 PF 3 NBr Se 6 I 5 C 2 S

Naming Covalent Compounds 1. Name the prefix for # of atoms in the 1 st element -If the prefix is mono, drop it 2. Write the name for the 1 st element 3. Name the prefix for the # of atoms in the 2 nd element 4. Take the root name of the 2 nd element and add “ide” *NO CHARGES

Examples 1. SO 2 2. N 2 F 5 3. CO 4. S 3 Cl 4 5. FI 3 • 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 = Ca. Cl 2· 2 H 2 O • Chromium (III) nitrate hexahydrate = Cr(NO 3)3· 6 H 2 O

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 H 2 S 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 • • • H 2 SO 4 Sulfuric acid HNO 3 Nitric acid H 3 PO 4 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 • • • H 2 SO 3 Sulfurous acid HNO 2 Nitrous acid H 3 PO 3 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 HCl. O 3 H + chlorate ic Chloric acid

More examples • • • H 2 SO 3 H 2 CO 3 HF Nitrous acid Perchloric acid Iodic acid • • • Sulfurous acid Carbonic acid Hydrofluoric acid HNO 2 HCl. O 4 HIO 3

Mixed examples (remember to figure out what type of compound it is 1 st!) • • KCl. O 2 CO 2 H 2 SO 4 NH 4 Br Cu. CO 3 Fe 2 O 3 HCl. O • • 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 • • CCl 4 PCl 5 Al 2 O 3 Cu(NO 3)2 HCl. O 2 H 3 P Fe(OH)3