This means you can vary the neutron number without changing chemical identity, because chemical identity is fixed by the proton.

这表示你可以改变中子数,而不会改变它的化学特性，因为化学特性是由质子决定的。

麻省理工公开课 - 固态化学导论课程节选

Now the last thing is that because the neutron has no net charge, we can change neutron number.

现在，最后一件事是,因为中子没有净电子，我们可以改变中子数。

麻省理工公开课 - 固态化学导论课程节选

So carbon 12. We know that it has the proton number, by definition, is 6. And the neutron number, 6 from 12 is 6. So it has 6 protons and 6 neutrons.

所以碳12，我们知道它有质子数，根据定义，那就是6，而电子数，12减6等于6，所以它有6个中子。

麻省理工公开课 - 固态化学导论课程节选