Please Don't Say Just Hi / Hello In Chat. It's as if you called someone on the phone and said "Hi!" and then put them on hold!
Chat communication should be done in a way that saves time for all participants and enables an efficient, asynchronous exchange of information. Don't expect an answer if you just write "Hello" in chat.
Instead, phrase a message that allows your chat partners to provide a meaningful response as soon as they allocate time to read and answer your message.
By saying just "Hello", you're trying to be polite by not jumping right into the request, like you would do in person or on the phone.
But Chat is neither of those things. Typing is much slower than talking.
Instead of being polite, you are just making the other person wait for you to phrase your question, which is lost productivity.