I want to do some serious bulking and I wondered if a 5 day split will do any good. I think that training 1 musclegroup a day is good cause then I can concentrate all my energy on just 1 musclegroup and really fatigue them. But I also think this won't give me enough rest to recover, ofcourse I could be wrong.

I was aiming for something like:

Monday - chest
Tuesday - arms
Wednesday - back & traps
Thursday - shoulders
Friday - legs & abs

Does this look like a good mass building plan?
any comments are appreciated

It may work if you keep the work sets to a minimum. The way you have the muscle groups scheduled might lead to overwork of certain bodyparts. Arms after doing chest the day before, will work the tri's 2 days in a row. Doing back after doing arms will overwork the bi's.

I like 3 day a week training for mass building.

Monday: Back, Delts

Wednesday: Quads, Hams, Calves

Friday: Chest, Tri's, Bi's

4-6 sets a bodypart, 4-8 reps per exercise

Increase weights anytime you reach 8 reps with good form and keep your protein levels high.

Just my suggestion for a 6-8 week cycle of training. You should see some good results. Good luck whatever you decide.