Writing Formulas and Naming Compounds

Oxidation Numbers Tells us how many electrons an has gained, lost, or shared to become stable Determined by the charge of the ion Transition elements have more than one oxidation number Expressed in Roman numerals Copper (II) = Cu +2

Neutral Compound Compounds want to be neutral. The total positive charges must equal the total negative charges. The charges cancel out.

Binary Ionic Compound Compound made of 2 elements A metal and a nonmetal

Writing Binary Ionic Compounds 1. Write the symbol of the element that has a positive charge or oxidation number. (Hint: The element is a metal.) 2. Write the symbol of the element with the negative charge of oxidation number. (Hint: The element is a nonmetal.) 3. The charge (without the sign) of one ion becomes the subscript of the other ion. 4. Reduce subscripts to the smallest whole numbers that keep the ration of ions.

Practice! 1. Na and Cl 2. Ba and F 3. K and S 4. Al and I 5. Ag and O 6. Mg and P 7. Pb and O 8. Pb and O 9. Li and Br 10. Zn and S

Writing Binary Compound Names 1. Write the name of the positive ion. (Hint: This is a metal.) 2. If the ion has multiple charges/oxidation numbers, determine which oxidation number is being used. 1. Keep in mind the overall charge is zero and the negative ion has only one charge. 2. Write the charge of the positive ion using roman numerals in parentheses after the ion’s name. 3. If the positive ion only has one possible oxidation number, go to step 3.

Writing Binary Compound Names 3. Write the root name of the negative ion. The root is the first part of the element’s name. 4. Add the ending –ide to the root.

Element Name-ide Ending OxygenOxide PhosphorousPhosphide NitrogenNitride SulfurSulfide

Practice! 1. BaCl 2 2. NaF 3. Al 2 O 3 4. K 2 S 5. CaO 6. Ba 3 P 2 7. Na 2 O 8. BeS 9. LiF 10. MgCl 2

Polyatomic Ions A positively or negatively charged covalently bonded group of atoms Contains 2 or more elements Writing Names 1. Write the name of the positive ion. 2. Write the name of the negative ion. Do not change the name of the polyatomic ion. Writing Formulas 1. Follow the rules for binary compounds, except that parentheses are around the polyatomic ion before adding the subscript.

Common Polyatomic Ions AmmoniumNH 4 + AcetateC2H3O2-C2H3O2- ChlorateClO 3 - NitrateNO 3 - HydroxideOH - CarbonateCO 3 -2 SulfateSO 4 -2 PhosphatePO 4 -3

Practice Writing and Naming 1. NH 4 + and Cl - 2. Li + and SO Ca 2+ and NO K + and SO Al 3+ and PO NH 4 + and OH -

Writing and Naming Binary Covalent Compounds Use Greek prefixes that show us how many atoms of each element are in the compound Last vowel of the prefix is dropped when the second element begins with a vowel Mono is often omitted

NumberPrefix 1Mono- 2Di- 3Tri- 4Tetra- 5Penta- NumberPrefix 6Hexa- 7Hepta- 8Octa- 9Nona- 10Deca-

Naming Covalent Compounds 1. CO 2. CO 2 3. SO 2 4. N 2 O 5. CCl 4 6. P 2 O 5 7. PCl 3 8. PBr 5