Chapter_20

Chapter_20 - Chapter 20 Oxidation Numbers 1. Elements...

Info iconThis preview shows pages 1–5. Sign up to view the full content.

View Full Document Right Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: Chapter 20 Oxidation Numbers 1. Elements always have oxidation number = 0. 2. Column I alkalai metals in compounds always have oxidation number = +1. 3. Column II alkaline earth metals in compounds always have oxidation number = +2. 4. Aluminum and gallium oxidation numbers are +3, zinc and cadmium are +2, and silver is +1. 5. Hydrogen normally has oxidation number = +1 in compounds except when combined with Colunm I or Column II elements; then rules 2 and 3 apply. 6. Oxygen normally has oxidation number = -2 except in H 2 O 2 (rule 4 has priority), or Column I and Column II oxides, where rules 2 and 3 apply. 7. To calculate other oxidation numbers pretend oxidation numbers are per atom charges and make all charges on all atoms total up to overall charge on ion or molecule containing atoms. Calculating Oxidation Numbers Each oxide ion has a charge of -2 7 oxide ions have a subtotal charge of -2 x 7 = -14 Since the formula has to be uncharged the 2 manganese ions have to have a +14 subtotal The +14 subtotal divided evenly over 2 manganese ions gives each manganese +14 / 2 = +7 This compound is manganese( VII ) oxide Work oxidation numbers of Cr and S in Cr 2 (SO 4 ) 3 (Hint: treat SO 4 2- as a single particle) Oxidation and Reduction 1. In simple chemical reduction-oxidation (redox) reactions one reactant substance contains an atom whose oxidation number increases when product is created. This substance becomes oxidized in the reaction. This substance is called a reducing agent or reductant because it causes another substance to become reduced. 2. The other reactant substance contains an atom whose oxidation number decreases when product is created. This substance becomes reduced in the reaction. This substance is called an oxidizing agent or oxidant because it causes another substance to become oxidized. Oxidation -Reduction Reactions I...
View Full Document

Page1 / 27

Chapter_20 - Chapter 20 Oxidation Numbers 1. Elements...

This preview shows document pages 1 - 5. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online