Question

An atom of an element has three electrons in the M shell. If M is the outermost shell, what is the atomic number of that element?

answer from the options
1. 3
2. 10
3. 13
4. 8​

Answer 1

Explanation:

K Shell has : 2 electrons L Shell has : 8 electrons M Shell has : 3 electrons a Electronic Configuration : 2,8,3 Total no : of electrons = 2 + 8 + 3 = 13 No : of electrons = No : of protons = 13 No : of protons = atomic no : of that element Atomic no : of the element = 13 b ) Valency is the combining capacity of an element.Since , this element has 3 electrons in its valence shell , the Valency of the element is 3 . c ) The element is Aluminium.It is a metal . The elements with valency less than 5 are metallic in nature . The elements with valency more than or equal to 5 are non metals . Elements which has fully filled shells are called noble gas / inert gas . Thus , Aluminium is metallic in nature . Please mark brainliest ...

Answer 2

Answer:

:D

Explanation:

We know that,

Mass Number = Number of protons + Number of neutrons

19 = p +10

p = 19 - 10 = 9

Since 'X' is a neutral atom,

Number of electrons(e) = number of protons (p) = 9

Therefore, the electronic configuration of 'X' is 2, 7. Here, L is the valence shell and there are seven electrons in valence shell.

Since the valency of an element is the number of electrons gained, lost, or shared to attain stable electronic configuration, the valency of 'X'  is 1.