An atom of an element has 2 electrons in the M shell i.e., third shell. What will be the atomic number of this element ? Name this element. Find the valency of this element. Also, find the number of neutrons in the atom of this element

CBSE Class 9 CBSE Class 9 Science
1

(i) Atomic number is 12
(ii) Element is magnesium.
(iii) Valency is 2 (+2)
(iv) No. of neutrons = Atomic mass-No. of protons
= 24 - 12 = 12