Question

what is meant by the term shieldind of electrons in an atom using LI atom as an example , describe the effect of shielding on the energy of electrons in an atom

Answer 1

The shielding effect describes the attraction between an electron and the nucleus in any atom with more than one electron.

Lithium atom belongs to group I ( Alkali metals) having atomic number 3. It is S-block element.

Its electronic configuration is Li(3) : 1s²2s¹

Electrons per shell (2, 1)

Here the 2 electrons from the inner shell shield the outer 1 electron ( valence shell electron) from the force of attraction exerted by the positive charge in the nucleus. The electron in 2s orbital is shielded from the full attraction of protons by the electrons of 1s orbital.

The effect of shielding on energy of electron in atom is that the valence shell electrons having lower energy is easily removed . In case of lithium by the removal of outermost electron it becomes a cation.