Question

Magnesium is an alkaline earth metal with an atomic number of 12. It’s in the third row in the periodic table. Which expression shows one way to find the number of valence electrons in one atom of magnesium?
A.12 × 3
B.12 ÷ 3
C.(12 − 8) − 2
D.(12 − 2) + 8
E.(12 + 2) − 8

Answer 1

ans is C

this will help you

Answer 2

Answer : The correct option is C.

Explanation :

Element = Magnesium

Atomic number = 12

The electronic configuration of Mg is, $1s^22s^22p^63s^2$

The outermost shell of magnesium is 3s which has 2 valence electrons.

Given options :

A) 12 × 3 = 36

B) 12 ÷ 3 = 4

C) (12 - 8) - 2 = 2

D) (12 + 2) - 8 = 6

The expression 'C' shows one way to find the number of valence electrons in one atom of magnesium.