What is the Chinese word for white people?

I think the Word you are thinking of is Gweilo. While the Word is used commonly is slang it is a derogatory term so should be used carefully. I'm a caucasian man who has traveled extensively in Asia and while I haven't been particularly offended when people used the term applying to me, you should be aware that the term (like Gringo) has racial/ethnic connotations. Gweilo doesn't translate very well and has been softened by common usage but it does roughly mean something like "ghost man" or, some suggest, "foreign devil."