The reaction between copper and oxygen
Copper is another metal that can form many oxides. The one formed when copper is heated and reacts with oxygen is copper (II) oxide, also known as cupric oxide.
|Copper||+||Oxygen||→||Copper (II) oxide|
When copper is placed in a flame with oxygen, the flame changes colour to a bright green. The copper (II) oxide that results is black and insoluble in water.