Chapter 3A - Redox Reactions

• reaction involving transfer of electrons from reductant to the oxidant • simultaneous oxidation & reduction processes

• addition/combination • decomposition • displacement • combustion

• loss of electrons • increased oxidation number

• gain of electrons • decreased oxidation number

A substance that causes another to be oxidised & itself reduced

A substance that causes another to be reduced & itself oxidised

Equation showing electrons as either a product or reactant

• two half equations written together • electrons/spectator ions omitted

• oxidised/reduced form of a substance • differ by one or more electrons • oxidised form written first (fewer electrons)

• redox reactions • ionic compound involves transfer of electrons

• redox reactions despite electrons shared in covalent bond • partial electron transfer occurs through an unequal sharing of electrons (electronegativity differences)

• O₂ usually assigned -2 but in peroxides assigned -1 • Hydrogen usually assigned +1 but in metal hydrides (-1) • The most electronegative element in a compound is assigned negative value