I just wanted to put this first because it feels like a dick move to say "You're wrong." then to follow up with, "But all that I said is dubious at best."

A counterpoint to my own thoughts would be that a single molecule of water does not have ANY of the properties we'd associate with liquid water. A single molecule of anything does not behave like a liquid, so the phrase, "a molecule of water," is a bit of a clusterfuck. It has meaning only when used casually, but if we get pedantic about it, there is no such thing as an isolated H2O molecule that behaves like a liquid and not a gas.

Quote Originally Posted by OngBonga View Post
Another fun watery fact is that water weighs less than air.
Correct-ish. Water vapor and steam (the gaseous forms of H2O) are less dense than air. For an equal volume of either compared with air, the water vapor or steam will weigh less than the air. Indeed, this is why clouds float in the sky.

Fun fact, the average weight of a rain cloud (cumulus cloud) is over 1 million pounds. Clouds are heavy AF, not because they're dense, but because they're huge.

However, in utter pedantry, water is the liquid form of an ensemble of molecules, and is about 1000 times as dense as its gas form, which has a different name. So saying water weighs less than air is literally incorrect and pedantically incorrect. It's just that, only the most utterly deranged pedagogue would waste time writing this out in a forum post.