Find the electron arrangement, the period and the group of the element with the atomic number 15.

The modern table is ordered by atomic number: $18$ groups and $7$ periods holding $2$, $8$, $8$, $18$, $18$, $32$ and $32$ elements. The period is the number of shells. Groups 1 and 2: group $=$ outer electrons. Groups 13 to 18: group $= 10 +$ outer electrons.