When to use the word un chaotic and non chaotic

I ould like to use this word , but which is correct , example of the sentence, she said the party was chaotic , I say no it was not, it was un chaotic or should I use non chaotic . thanks

Unchaotic is not a word, non-chaotic is.

non-chaotic is the correct word to use.
However, I find that using this word makes this particular sentence feel awkward and variable. I would rewrite it into something as simple as; "it wasn't chaotic" or "the party was chaos free" or "the party lacked chaos".