Redox
Reduction
Oxidation
Loss of oxygen
Gain of oxygen
Gain of hydrogen
Loss of hydrogen
Gain of electrons
Loss of electrons
● Reactants which undergo oxidation → reducing agent
● Reactants which undergoes reduction → oxidizing agent
● Oxidation number /state
○ The total number of electrons lost or gained for a chemical bond to be formed
● Rules of assigning oxidation number
○ The oxidation number of an atom by itself is zero
○ The oxidation number of any monatomic ion is equal to its change
○ The oxidation number of elements in a compound are written per atom
○ The sum of the oxidation number in a compound is zero
○ The sum of the oxidation number in a polyatomic ion is equal to the ions change
○ Oxidation numbers to remember
■ Elements in group 1 → +1
■ Elements in group 2 → +2
■ Aluminium → +3
■ Fluorine → -1
■ Hydrogen → +1
■ Oxygen → -2
● Oxidation number sign is written before the number while the ion charge is written after the
number
● Oxidation → the oxidation number of 1 or more
● Reduction → a oxidation number of -1 or less
● Oxidation number of NO
○ X -2 = 0
X = 2
● CO2 + C → 2CO
○ Reduction = CO2 → 2CO
○ Oxidation = C → 2CO
● Colour changes
○ Potassium manganate
■ Reducing agent turns purple to colourless
○ Potassium iodide
■ Oxidising agent turns colourless to red-brown
○ Potassium dichromate
■ Reducing agent turns from orange to green
