Chemistry is a Bitch

Molecules, atoms, all of that such and such,
kill me, please, it's all too much.
Electricity and ions,
don't get started with nucleons.
It is general, it is chemistry,
all I want is this class to be history.
A constant is a constant,
but not all are constant.
Riddle me this, riddle me that,
lone pairs take up space- they're just fat.
I'll let you know now,
my rant has ended... I'll take a bow.