3.1.7 - Oxidation, reduction and redox equations Flashcards
Define ‘oxidation’ in terms of
a) electrons
b) hydrogen
c) oxygen
Oxidation is
a) a loss of electrons from a species
b) a loss of hydrogen from a species
c) a gain of oxygen by a species
Define ‘reduction’ in terms of
a) electrons
b) hydrogen
c) oxygen
Oxidation is
a) a gain of electrons from a species
b) a gain of hydrogen from a species
c) a loss of oxygen by a species
Define the term ‘oxidising agent’
A substance that causes oxidation by being reduced itself
Define the term ‘reducing agent’
A substance that causes reduction by being oxidised itself
Oxidation state of hydrogen?
Usually: +1
Exception: with metal hydrides, hydrogen is -1
Oxidation state of group 1 metals?
Always +1
Oxidation state of group 2 metals?
Always +2
Oxidation state of aluminium?
Always +3
Oxidation state of oxygen?
Usually: -2
Exception: peroxides (H2O2) oxygen is -1; and in OF2, oxygen is +2
Oxidation state of fluorine?
Always -1
Oxidation state of chlorine?
Usually: -1
Exception:with fluorine or oxygen, chlorine is POSITIVE
Rule for assigning oxidation states?
The most electronegative element always has the negative value
What are the 4 most electronegative elements?
Chlorine < Nitrogen < Oxygen < Fluorine (most)
What does the oxidation state of an element in an IONIC compound tell you?
The number of electrons lost/gained by the ion compared to in its uncombined form
What does the oxidation state of an element in an MOLECULAR compound tell you?
The distribution of electron density between the atoms, due to differences in electronegativities (more electronegative means a negative oxidation state)
