Unc I wouldnt say it was sh!te mate, but by training arms the first day of the week you could still have some potential overlap on the friday (ie arms and shoulders will still be fatgued) when you are doing chest back.
Plus chest and back in the same workout is a big ask, it can be done but its not for the fainthearted...
General rule when constucting a routine will be to start with the largest and most taxing to train bodyparts and work down, and construct so there is no overlap from the previous workouts..
Forgetting about exercises for a moment this is what im running for example.
Monday: Quads/hams/Calves
Wednesday Abbs/Chest/Front Delts/Triceps
Friday Back/Side and rear Delts/Biceps
I split and hit shoulders twice cause its an area im trying to bring up, but for most it could just drop into either the chest or back workout.
Now with something like that you hit Legs when your fresh on Monday.
Therse no overlap on Wednesday as your triceps are fresh to really push on chest and shoulders, and you hit hit em with a couple of sets at the end of the workout to finish them off (they will already have had a damn good workout from chest and shoulders really)
Friday your biceps havent been hit all week so they are fully charged so you can hit the back exercises at 100%, and then just cream them off at the end of the workout.
So you have got optimun recovery for each bodypart. Train smarter not harder is the key here
Theres no reason why you couldnt swap chest and back days around depending on which you wanted to prirotise. Or even do the chest and back workouts first and leave legs till last if for example legs was a strong area for you..
Have a think about it and decide what days you wana do what on and then we'll get into the nitty gritty of exercises etc..