There is an element x ( atomic no. 19, atomic mass 40) (10) (a)what is its correct ground state orbital configuration (b) which group does it belongs to ? (c) which period does it belongs to (d) how many shells does it have ?

a)

b)  group no : 1

c) period no : 4

d) 4 shells

Explanation:

Electronic configuration represents the total number of electrons that a neutral element contains. We add all the superscripts to know the number of electrons in an atom.

The electrons are filled according to Afbau's rule in order of increasing energies and thus the Electronic configuration for element X with atomic number of 19 and thus 19 electrons is:

b) The group for elements whose last electrons enter the s orbital is given by the number of electrons present in the valence s orbital. Thus the group number is 1.

c) The period of the element is given by the principal shell of the valence electron. Thus as last electron enters 4th main shell, the period number is 4.

d) The shells are given by the the value of principal quantum number and thus there are 4 values of principal quantum number i.e 1, 2 , 3 and 4 and thus there are 4 shells.