Summary EDEXCEL A-LEVEL CHEMISTRY REVISION NOTES: REDOX 1

, 3 -
Redox
Redox
Chemistry


Oxidation land therefore reduction can e defined as:



↓) oxygen:
· oxidation is the gain of oxygen
· Reduction is the loss of oxygen

2) Hydrogen:

· oxidation is the loss ofhydrogen

· Reduction is the gain of hydrogen


Electrons:
3)

o oxidation is the loss of
electrons

· Reduction is the gain electrons
of



4) oxidation Numbers:

o oxidation involves an increase in oxidation number

· Reduction involves a decrease in oxidation number




Oxidation Number:
· The number ofelectrons gained or lost if the compound were to be

considered fully ionic



· Bules for assigning oxidation number

1) the atom
If is in an element, o.N. 0
=




2) Flourine is always o.N.=-1


3)Hydrogen is usually 0. N. =
+1


*yorogen can be 0.N=-1 in compounds with reactive metals

4) oxygen is usually 0.N.=-2

oxygen can be o.N=-1 in peroxide H202
0.N.= +2 in Ofz

0.N. 0
= in 02/03

5)Use Periodic table/common sense

e.g. group 2 likely to be +2

group I likely to be th

0.N.'s usually so in twos


Roman Numerals
oxidation state of elementin a
·
Roman numerals are used to show an


compound which has variable oxidation states