Final answer:
The word equation for the reaction is 'solid copper reacts with oxygen gas to produce solid copper(II) oxide.' The oxidation state of copper is changing in this reaction.
Step-by-step explanation:
The word equation for the given chemical reaction is:
Cu (s) + O2(g) → CuO(s)
This can be read as 'solid copper reacts with oxygen gas to produce solid copper(II) oxide.'
In this reaction, copper (Cu) is being oxidized from its elemental state (0 oxidation state) to copper(II) ion (Cu²+) with a +2 oxidation state.