How to find a i3 processor is 1st generation or 2nd generation

See first gen cpu are 3digit model no like i3 530,i3 540 etc while 2nd gen have 4digit and it will start from '2' like i3 2100,i3 2120 and 3rd gen will start from '3' like i3 3220,i3 3225.remember 1st gen cpu uses socket lga 1156 whereas 2nd and 3rd uses lga 1155.3rd gen i3 is best among all.
 
+1 for Scott and ASHISH65

If have the processor already in a system and you are trying to find out which one you have simply run CPU-Z and it will tell you the model # move from there to the ark.intel.com site and look up the model # to see which family it fits within.