Is it normal for jack russels to become aggressive?

by Amber
(United Kingdom)

He was lovely as a pup and still is a lovely, adorable dog that loves fuss! but the problem that me and my family have now is that he seems to snap and growl and chase his tail when you tell him to go to his bed, and he barks and growls when someone leaves the house even family... is this normal? should we try spraying water or something on him when he starts to act in this stupid manner? (He has been castrated)
as i say he's a lovely, caring dog, we are just at wit ends to be honest!!