Question

The atomic number of Magnesium is 12. Which of the following answers is true? (Choose all that apply)

Answer 1

Answer : The correct options are:

(b) Magnesium has 2 electrons in it's valence shell

(d) Magnesium is neutral in it's elemental form

Explanation :

Atomic number : It is defined as the number of protons or number of electrons.

Atomic number = number of protons = number of electrons

Mass number : It is defined as the sum of number of protons and number of neutrons.

Number of neutrons = Mass number - Number of protons

Electronic configuration : It is defined as the representation of electrons around the nucleus of an atom.

Number of electrons in an atom are determined by the electronic configuration.

As we are given :

Atomic number of magnesium = 12

Number of protons = Number of electrons = 12

Magnesium is the alkaline earth metal that belongs to group 2 and has 12 electrons in their shell.

The electronic configuration of magnesium (Mg) will be:

$1s^22s^22p^63s^2$

From this we conclude that, there are 2 electrons in it's outermost or valence shell and it is neutral in it's elemental form because magnesium has same number of protons and electrons.

Hence, the correct options are, (b) and (d)