Two chemists go into a restaurant. The first one says "I think I'll have an H2O." The second one says "I think I'll have an H2O too" - and he died.

 904

0  

Helium walks into a bar. The bartender says "We don't serve noble gasses in here." Helium doesn't react.

 2090

1  

Money has recently been discovered to be a not-yet-identified super heavy element. The proposed name is: Un-obtainium.

 2498

1  

An instructor in chemical warfare asked soldiers in his class: "Anyone knows the formula for water?" "Sure. That's easy," said one man. "What is it?" "H, I, J, K, L, M, N, O." "What, what?" reasked the instructor. "H to O," explained the chemistry expert.

 895

1  

Q: Why was the mole of oxygen molecules excited when he walked out of the singles bar? A: He got Avogadro's number!

 2020

5