The 2 tb drive will work but only 1 tb of the drive will be used and you will have no access to the other 1tb on the drive. Raids can only use the size of the smallest drive to build with. ie a 10mb drive and a 10tb drive in raid0 will create a 20mb raid0 (2*10mb) . In your case your smallest drive is 1tb.
The formula to calculate the size of a raid5 is (N-1)*Smin where N is the number of drives and Smin is the size of the smallest drive.