How do you logout (and stay logged out) of facebook chat on a phone?

I have an android powered phone. I'll log on to facebook on a computer to find that I have missed chat messages because my phone keeps me logged in and active on chat, even when I'm not using it. My phone doesn't actually send me the notifications that I have a new message, so it's completely pointless of being logged in and able to receive messages when I'm not aware I'm getting them. It's take a while to log me out of chat on the computer anyway, but just being on 24/7 because of my phone is ridiculous.. nobody knows when I'm actually online. It's just bugging and I was wondering if anybody knew how to fix this problem?