I was curious (because I didn't know) what is it about an element that determines whether it's a solid, liquid or gas?
For example, why is Mercury the only metal that's a liquid at room temperature whereas all of the others have such high melting points? Why is having 80 protons "special" in this way while 79 and 81 don't even come close?
Why are most of the low numbers gaseous yet a few aren't?
At first glance, there seems to be no apparent logical connection between the atomic number and the solidity of an element, or is there one but I'm just ignorant of it?