There are several unstable molecules that have that chemical formula ( .CH₃ radical, which has a neutral charge one unpaired electron; + CH₃ methylium cation, which is missing that one unpaired electron; and -CH₃ methanide anion, which has an extra electron). CH₃ when bonded to many other atom or as part of a molecule is very common and called a methyl group. All of these four types of CH₃ have very different properties and chemistry. If you let me know which one you are interested in or more about your project I can help you more.

CH₃ is not a molecule, so I am not sure what are you asking about. It would help me if you put the question in context - where does the interest in "CH3" come from, what kinds of properties are you curious about?CH₃ is not a molecule, but it could be a short-lived intermediate/reactive species, as CH₃(+), CH₃(-), or CH₃(the radical).