The real question is whether your co-worker's chip on his shoulder came from his own head (sort of a chip off the old block), or whether the chip is a result of working with four people who ignore him.
Look first at your group to see if you have formed a clique that makes him an outsider. If this is the case, his behavior may be a defensive reaction to being excluded.
However, if the four of you have honestly tried to communicate with him and include him in the group, only to be ignored or subjected to verbal venom, it is easy to conclude that you should just work around him. However, you have already found that doing so is rather unpleasant.
A different approach is to meet with him and tell him that you need his help. Let him know that you are concerned about working with him, and you would like to know what he needs in order to build a more productive working relationship.
If he picks up the cue, listen carefully to what he says; if he picks up the cue and breaks it, you should go on with your work, recognizing that you did all you could to solve the problem. However, if his actions are disrupting the productivity of the office, this is a cue that your manager should pick up.
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