Question

If the number of electrons in the inner shells increases then (1) Ionisation potential increases (2) Screening cffect increases (3) Shielding effect decreases (4) Nuclear attraction on outer electrons increases

Short answer

Screening effect increases.

Step-by-step solution

Define Key Terms

Ionisation potential is the amount of energy required to remove an electron from an atom or ion in its gaseous state. Screening effect and shielding effect both refer to the phenomena where inner electrons partially block the attractive force of the nucleus on the outer electrons.

Understand the Impact of Inner Electrons

When the number of electrons in the inner shells increases, these electrons act as a shield between the nucleus and the outer electrons, reducing the effective nuclear charge experienced by the outer electrons.

Determine the Screening Effect

Since more inner electrons will increase the 'blocking' of the nuclear charge, the screening effect increases. This helps to buffer the complete nuclear charge felt by outer electrons.

Analyze the Shielding Effect

The shielding effect also increases because the same inner electrons are effectively reducing the nuclear pull on the outer electrons, making it easier for those electrons to be less tightly held.

Consequence on Ionisation Potential

A higher screening and shielding effect means that the outer electrons are less strongly attracted to the nucleus, thus leading to a decrease in ionisation potential.

Evaluate Nuclear Attraction

With increased screening and shielding, the nuclear attraction on outer electrons decreases because the inner electrons reduce the effective nuclear charge.

Final Answer

The correct implication of an increase in the number of inner shell electrons is that the screening effect increases.

Key concepts

Ionisation Potential

Ionisation potential is the energy required to remove the most loosely bound electron from an isolated gaseous atom. It describes how tightly an atom holds onto its outermost electron.

When inner shell electrons increase, they shield outer electrons from the nucleus, decreasing the effective nuclear charge experienced by these outer electrons.

Therefore, less energy is needed to remove them, and the ionisation potential decreases. A higher ionisation potential means it requires more energy to remove an electron, indicating a stronger pull by the nucleus on the electron.

Screening Effect

The screening effect, also known as the shielding effect, occurs when inner electrons reduce the effective nuclear charge experienced by outer electrons. These inner electrons 'screen' the outer electrons from the full force of the nuclear charge.

More inner electrons mean a stronger screening effect, as they block more of the nuclear charge. Consequently, outer electrons feel a weaker attraction to the nucleus.

Increased inner electrons enhance this screening effect, making it harder for the nucleus to attract the outer electrons strongly.

Shielding Effect

The shielding effect is closely related to the screening effect. It describes how inner shell electrons can 'shield' outer electrons from the attractive force of the nucleus.

When the number of inner shell electrons increases, the shielding effect becomes more pronounced. The outer electrons are less attracted to the nucleus because the inner electrons block some of the nucleus' positive charge.

As a result, outer electrons experience less nuclear pull and are more easily influenced by external forces, making them easier to remove.

Nuclear Attraction

Nuclear attraction refers to the force exerted by the positively charged nucleus on the negatively charged electrons. This force keeps the electrons bound to the atom.

As inner shell electrons increase, they act as a buffer, reducing the effective nuclear charge experienced by outer electrons. This means the outer electrons feel less attraction to the nucleus.

Higher numbers of inner electrons decrease nuclear attraction on outer electrons, making these outer electrons easier to remove and less tightly bound to the atom.