Tetravalent nitrogen is plus.

成了四个键的氮带一个正电
So there's just a Coulombic attraction between ammonium and chloride.

所以与氯离子间有库仑引力
So that's a great contribution.

这是项很伟大的贡献
Now there are other things

运用路易斯结构
you can understand in terms of Lewis structures.

我们还能明白样东西
Like you have an amine and it can react with an oxygen to give an amine oxide,

像胺可以和氧反应形成氧化胺
which is positive on nitrogen, negative on oxygen.

氮上带正电氧上带负电
Or you can have a sulfide, which can react with an oxygen,

硫化物也可以和氧反应
to give a sulfoxide.

生成亚砜
Or what else can happen,with a sulfur,

硫化物还可以继续反应
what additionally can happen?

还能怎么加
It could do another oxygen,

还能再加一个氧