Question

Name of the element	Symbol of the element	Atomic number	Mass number	No. of protons	No. of electrons	No. of neutrons	Electronic configuration
Calcium	$\mathrm{Ca}$	20			20

Answer 1

Calculate the number of protons in calcium:

Number of protons$=$Atomic number

Thus,

Number of protons$=20$

Calculate the number of neutrons in Calcium:

Number of neutrons$=20$

Calculate mass number of Calcium:

Mass number$=$Number of protons$+$Number of neutrons

Thus,

Mass number$=20+20=40$

Write the electronic configuration of Calcium

1. The total number of electrons in Calcium atom is $20$.
2. Starting from the nucleus, the first shell i.e. K shell holds 2 electrons, the second shell i.e. L shell holds 8 electrons. Thus, 10 electrons are filled.
3. Now, the third shell i.e. M shell is expected to hold the remaining 10 electrons.
4. But according to Bohr Bury scheme, the outermost shell cannot hold more than 8 electrons.
5. Thus, the M shell holds 8 electrons and the remaining 2 electrons go into the fourth shell i.e. N shell.
6. Thus, the electronic configuration is K=2, L=8, M=8, N=2

Thus, the complete chart is given as:

Name of the element	Symbol of the element	Atomic number	Mass number	No. of protons	No. of electrons	No. of neutrons	Electronic configuration
Calcium	$\mathrm{Ca}$	20	40	20	20	20	K=2	L=8	M=8	N=2