A neutral atom has a configuration of 1s22s22p5. Which group on the periodic table contains this atom?
A. 3
B. 5
C. 17
D. 2

C

Explanation:

The atom has an electron configuration of 1s²2s²2p⁶3s²3p⁵.

The total numbe of electrons present in the shell is 17 electrons. To determine the group of the atom, we have to check what orbital did the last electron stop.

If it's in S-orbital, then we automatically knows it's an s-block element which could either be group 1 or 2 and can still be furthered down to know which group it's in.

But in this case, the last electron is in s-orbital. To determine the group number of p-orbitals, we'll have to consider the preceding s-orbital and add it to it, then count it in 10s.

For example, if the last two orbital is 3s² 3p¹, 2 + 1 = 3, add ten (10) to it = 13. Hence the element is in group 13.

In this case, we have 3s² 3p⁵ = 2 + 5 = 7 + 10 = 17.