All the expressions of words and letters before the ion in the ninth grade
1、 The reaction of substance and oxygen: (1) the reaction of elemental and oxygen: 1. Magnesium burning in air: 2mg + O2 igniting 2MgO 2. Iron burning in oxygen: 3Fe + 2O2 igniting Fe3O4 3. Copper heating in air: 2Cu + O2 heating 2CuO 4. Aluminum burning in air: 4Al + 3O2 igniting 2A