Herbert Nehrlich - H 2 O

Her name was oxygen, short form O-2
she was just floating there, above the lake
when something thin and wearing just one shoe
by name of hydrogen, a common flake
came rushing up to meet that chubby thing
which had two legs to dance with, he had only one
but when he touched, the water made him dance and sing
while that chubby one was sitting on her bun.
Above the waves that day they did combine their souls
though it was necessary to recruit one more
so that their dance could then proceed on four whole soles
and they made history as chemistry's folklore.

Herbert Nehrlich

http://www.poemhunter.com/poem/h-2-o/