Question

Screening effect is not common for the elements of the period

Answer 1

Answer:

Normally, the screening effect takes place for the elements which have a high atomic number and have a large number of electrons in their inner orbits. ... Here all three elements have a small atomic number and have only 1 electron thus does not have enough electrons to perform screening effect.

Hope it helps

Answer 2

Answer: It is  not common for the elements of period $1$.

Explanation:

• The outermost electrons are  shielded from the nucleus when there are more inner electrons present, which allows it to be free of any nuclear pull which is known as shielding or screening effect.
• The shielding effect experienced by the outermost electrons increases with the number of electron shells.
• Normally, the screening effect occurs for elements with high atomic numbers and more of electrons in their inner orbits.
• Therefore period $1$ of the periodic table having two elements H and He with $1$ and $2$ electrons respectively do not experience screening effect.

So screening effect is not common for the elements of period $1$.

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