Question

What is Valency and atomic mass of all elements in whole number?

Give only 1 valency and atomic mass for 1 elements.

Answer 1

Every atom has a nucleus which contains Protons (+ ve charged) and Neutrons (0 charge). The electrons ( -ve charged) are present as equal numbers of protons.

Electrons are revolving around the nucleus like the planets revolves around the Sun.

The outermost orbit (path way of the electrons revolving) is called Valence shell. The number of electrons present in the outermost shell called 'Valence electrons"

For example:
Atomic number for Aluminium = 13
Atomic number = Number of protons = Number of electrons = 13.

Valence electron for Al = 3 electrons.

Electron dot structure ( use only valence electrons as dots)

Formation of ions:
Formation of cation (Positive ion)
By losing the elctrons in the outermost shell, it forms cation (positive ion).

Al has 13 protons (+13) and 13 electrons (-13).
Totally it has +13 -13 = zero.

After "losing" to 3 electrons from it outermost shell (but not lose of protons),
it has 10 electrons (-10).
Totally it has +13 -10 = +3
Al has +3 ion, it is a cation (positive ion).

It means the valency of Aluminium is +3


Please follow the same idea to formation of anion (negative ion)
Example: F has atomic number 9, it means it has 9 protons and 9 electrons.
Totally it has +9 - 9 = 0

After "gaining" of 1 electron, it becomes 10 electrons totally.
The charge = 9 protons + 10 electrons.
= +9 - 10 = -1
F has -1 ion, it is an anion (negative ion).

It means the valency of F is -1.

Atomic mass:
It is the mass of one mole atom. It is the sum of the protons and neutrons.
Let us check first 20 elements atomic mass and its valency.