原子数，原子价，化合价。

The number of atoms in a molecule.

碳的化合价是4价。

Carbon has a valency of 4.

在反应中还原剂中元素的化合价升高。

Reductant in the reaction of elements in valence increased.

所有的碱土金属元素的化合价都是+2，这使他们非常活泼，因为他们非常活泼，也不在自然界中直接出现。

All alkaline earth elements have an oxidation number of +2, making them very reactive. Because of their reactivity, the alkaline metals are not found free in nature.

报道了烷基碳原子数和钼的化合价对硫磷钼型极压添加剂(简称极压剂)的极压抗磨性能的影响。

The effect of alkyl carbon Numbers and the valence of Mo on the performance of extreme pressure additive was investigated.