Question

21. An element with atomic number 20 will be placed in which period of the periodic table with explanation​

Answer 1

Answer:

An element with ‘atomic number’ 20 is belongs to 4th period.

Explanation:

An element with an atomic number is 20, the electronic configuration is:

1s²2s²3s²3p to the power 6 4s²,

The last electron means differentiate electron is enters into the fourth orbital. It is indicates the period number.

The “outer electronic configuration state” is, therefore the period number is four.

Hence, the period number of an element have 20 is placed in the ‘fourth period’ of the ‘periodic table’.

Hope it helps you.

Answer 2

20 is calcium and is placed in the s block because it is an alkali metal