What is the number of valence electrons for Sn?

Sn has 50 total electrons and is in the Group 4a elements on the Periodic Table. The nearest Noble Gas that is before Sn is Kr, which has 36 electrons. Therefore, the number of inner electrons (the same as Kr's electrons) is 36, outer electrons is 4 and valence is 4 as well (because its a Group 4a