I contain a tin ion
And you cannot find me in a crayon
But don't worry little peon
You can find me in a swan
You can find me in a heron
You can even find me in a fawn
You need me to move
Without me you will just be like a puddle of goo
You should not let me touch others like me
I promise you, I'm worse than an angry bee
Beware my wrath,
It's worse than an icy cold bath
But on the upside - I can help you do math!
To get your answer accepted you need to get the word and explain what most of the lines/groups of lines refer to
Hint #1:
The pain the fourth stanza talks about happens mostly to older people