What are the atomic numbers of elements whose outermost electrons are represented by
(a) 3s1 (b) 2p3 and (c) 3p5?
[a] 3s1
Completing the electron configuration of the element as 1s2 2s2 2p6 3s1.
∴ Number of electrons present in the atom of the element
= 2 + 2 + 6 + 1 = 11
∴ Atomic number of the element = 11 [sodium]
[b] 2p3
Completing the electron configuration of the element as 1s2 2s2 2p3
∴ Number of electrons present in the atom of the element = 2+ 2 + 3 = 7
∴ Atomic number of the element = 7 [nitrogen]
[c] 3p5
Completing the electron configuration of the element as 1s2 2s2 2p5
∴ Number of electrons present in the atom of the element = 2 + 2 + 5 =9
∴ Atomic number of the element = 9 [fluorine]