Question

What is the significance of atomic number in the modern classification of elements? Explain with the help of example.

Answer 1

The atomic number gives the number of protons in an atom. The no. of protons is equal to the number of electrons in a neutral atom. Meaning from the atomic no. we can get the number of electrons.

From the number of electrons we can get the electron arrangement
For example Sodium
No. of protons = 11
No. of electrons = 11
Electron arrangement = 2.8.1

From the electron arrangement we can now tell the group and period in which the element belong.
Group = No. of electrons in the outermost energy level
Period = No. of energy levels

Sodium has one electron in its outermost energy level (2.8.1.)
Sodium has 3 energy levels (2.8.1.)

Therefore
Sodium is in Group I and Period 3

Answer 2

Answer:

here is your answer...................