Naming and Writing Formulas for Compounds

NAMING AND WRITING FORMULAS FOR COMPOUNDS

Unit 4

1. NAMING IONIC COMPOUNDS

• Ionic Compound: • Composed of ions• Cations & Anions• Metals & Nonmetals

Cations: • + charge• Metals• + Polyatomic Ions

Anions: • - charge• Nonmetals• - Polyatomic Ions

1. Name the cation (always 1st)2. Name the anion – add “ide” ending

(always 2nd)If anion is polyatomic, just use name (no ending)

* This is for cations with a single charge (oxidation state)

• For cations with more than one oxidation state• Name the cation • Add roman numeral to indicate charge of the cation

2. WRITING THE FORMULAS FOR IONIC COMPOUNDS

1. Write the cation symbol2. Write the anion symbol (or polyatomic formula)3. Balance + and – charges so they add to zero

3. NAMING AND WRITING FORMULAS FOR MOLECULAR COMPOUNDS

• Molecular Compounds• Nonmetals only• Use greek prefixes to tell # of atoms

1 – mono2 – di3 – tri4 – tetra5 – penta6 – hexa7 – hepta8 – octa9 – nona10 - deca

4. ACIDS

• Recognizing an acid• Molecular compound beginning with “H” (or H2 or H3)

• May contain polyatomic ions

Binary Acids1. Start name with “hydro”2. Use anion name adding “ic” ending3. End with “acid”

Oxyacids1. Use polyatomic ion name

1. Add “ic” in place of “ate”2. Add “ous” in place of “ite”

2. End with “acid”

Writing Acid Formulas1. Write the symbol for hydrogen 1st

2. Write the symbol for nonmetal or polyatomic anion3. Balance + and – charges so they add to zero

• (H will have a charge of +1)

5. DIATOMIC MOLECULES

• 2 of the same atom bonded together• Some elements naturally exist as diatomic

H, N, O, F, Cl, Br, I

6. HYDRATES

• Ionic salt with molecules of water attached

Naming Hydrates1. Name the ionic compound 2. Use a greek prefix for number of water

molecules3. End with “hydrate”

Writing the Formulas for Hydrates1. Write the formula for the ionic compound2. Indicate the number of water molecules with big

number in front of H2O

7. COMPOUNDS WITH COMMON NAMES

1. H2O2. NaHCO3

3. H2O2

4. NH3

5. CH4

6. HCH3COO (HC2H3O2)