Most of chemistry has gone SI so every mass should be in kilograms.

大部分的化学遵守国际单位制,所以质量的单位应该是千克。

麻省理工公开课 - 固态化学导论课程节选

Atoms of different elements have different weights and different chemical properties.

不同元素的原子的质量不同,化学特性也不相同。

麻省理工公开课 - 固态化学导论课程节选

What I am going to do next day is go into the larger stoichiometry and understand the principles of mass balance and reactivity But before you go,hold it,I don't want you racing off.

下堂课我要做的是,讨论化学计量学，和,质量平衡很反应定律,但在下课之前，我不希望你们这么快走。

麻省理工公开课 - 固态化学导论课程节选