Writing Formulas Oxidation Numbers & Chemical Formulas Mrs. Wolfe

Vocabulary: Another word for Charge is OXIDATION NUMBER.

Is there a pattern of Oxidation Numbers on the Periodic Table? What is the charge of a Hydrogen ion? + 1 (sometimes –1) Lithium? Also +1 Beryllium? Magnesium? Both +2 Fluorine? Chlorine? Both -1 There IS a pattern! Let’s write that on our Periodic Tables.

NA Common Oxidation Numbers

There are some Polyatomic Ions. Polyatomic Ions – combination of elements WITH A CHARGE! You will always have a chart of their oxidation numbers on a test/quiz. HERE COMES A HANDOUT!

We can use oxidation numbers to write formulas. Remember, compounds must be NEUTRAL. Cl 1 Na 1 NaCl

Ionic Bonds & Formulas Write each ion, cation first. Use parentheses to show more than one polyatomic ion. Roman numerals = transition metal ion’s charge

potassium + chlorine magnesium + nitrate copper(II) + chlorine K + Cl  Mg 2+ NO 3  Cu 2+ Cl   KCl  Mg(NO 3 ) 2  CuCl 2 Practice Problems:

Time for a WS, then Labs! Qualitative Ion Testing Lab Formula of an Ionic Compound Lab

Some elements are diatomic.

NOF Cl Br I H The SEVEN diatomic elements Br 2 I 2 N 2 Cl 2 H 2 O 2 F 2

Time for a WS, then GAMES! Formulas of Compounds WS Rummy!

Naming Ionic Compounds Write the names of both ions, CATION first. Change ending of ANION to -ide. Polyatomic ions have special names. Use Roman numerals to show the ion’s charge if more than one is possible. (Transition metals)

NaBr Na 2 CO 3 FeCl 3 –sodium bromide –sodium carbonate –iron(III) chloride Practice Problems

Naming Covalent Compounds 1.Less e - neg atom comes first. 2.Add prefixes to indicate # of atoms. 3.Change the ending of the second element to -ide.

PREFIX mono- di- tri- tetra- penta- hexa- hepta- octa- nona- deca- NUMBER Molecular Prefixes

CCl 4 N 2 O SF 6 –carbon tetrachloride –dinitrogen monoxide –sulfur hexafluoride Practice Problems

arsenic trichloride dinitrogen pentoxide tetraphosphorus decoxide –AsCl 3 –N2O5–N2O5 –P 4 O 10 Practice Problems

Let’s do a WS!