Group 2 Redox Reactions with Oxygen

Group 2 metals all react with oxygen to form metal oxides. The M²⁺ ions form ionic bonds with O^2-ions.Magnesium burns with a brilliant white light to form magnesium oxide.2Mg(s) + O₂(g) → 2MgO(s)This is a redox reaction. Each metal atom loses two electrons and is oxidised, and each oxygen atom gains two electrons and is reduced. The balanced equation is:2Mg(s) + O₂(g) → 2MgO(s)The oxidation state of magnesium increases from 0 to +2 and the oxidation state of oxygen decreases from 0 to -2. The Group 2 metal acts as a reducing agent. For any Group 2 metal M:2M(s) + O₂(g) → 2MO(s)The reactions are exothermic and give out energy to the surroundings. The electrostatic attraction between the M²⁺ ion and the O^2- ion is an ionic bond, so the oxides exist as giant ionic lattices. They are all white solids with high melting points.Reactivity with oxygen increases down the group, because the outer electrons are further from the nucleus and more shielded, so they are lost more easily.