Question

the monovalent anion of an element completely filled L shell find atomic number, electronic configuration, electrons, protons and neutrons of mass number is 19​

Answer 1

Solution :

Atomic number = 19

Number of protons = Number of electrons = 19

Mass number = Number of protons + Number of neutrons

39 = 19 + N

N = 20

Electronic configuration

19 = (2, 8, 8, 1)

Electrons in K shell (1st) = 2

Electrons in L shell (2nd) = 8

Electrons in M shell (3rd) = 8

Electrons in N shell (4th) = 1

Valence electrons is the number of electrons in the outer shell, i.e. 1 in this atom.