As we move from B to Al in the p-block elements the sum of the first three ionisation enthalpiesa)slightly decreasesb)remains the samec)considerably decreasesd)increasesCorrect answer is option 'C'. Can you explain this answer?

Question

Answer

Answer

Ionisation enthalpy is defined as amount of energy required to remove one Valence electron  from an isolated neutral gaseous atom that results in formation of a monovalent positive ion.And in p block as we move down the group from boron to aluminium the ionisation power decreases because size of a atom and nuclear charge increases down the group and as size of atom dominates the magnitude of nuclear charge .As a result the I.E decreases

Answer

The ionization enthalpy is the energy required to remove an electron from an atom or ion in the gaseous state. As we move from boron (B) to aluminum (Al) in the p-block elements, the sum of the first three ionization enthalpies considerably decreases.

Explanation:
1. Definition of ionization enthalpy:
- Ionization enthalpy is the energy required to remove an electron from an atom or ion in the gaseous state.
- It is an endothermic process, meaning energy is absorbed in order to remove an electron.

2. Factors affecting ionization enthalpy:
- Nuclear charge: The stronger the nuclear charge, the higher the ionization enthalpy.
- Atomic radius: The smaller the atomic radius, the higher the ionization enthalpy.
- Electron-electron repulsion: If there are more electrons in the same energy level, they will repel each other, making it easier to remove an electron.

3. Explanation of the trend in ionization enthalpy:
- As we move from boron (B) to aluminum (Al) in the p-block elements, the nuclear charge increases as we move across a period.
- However, the effect of increased nuclear charge is counteracted by the increase in atomic radius.
- The atomic radius increases due to the addition of new shells as we move down the group.
- The increase in atomic radius leads to a decrease in ionization enthalpy because the outermost electrons are farther from the nucleus and experience weaker attraction.
- Additionally, there is a shielding effect of inner electrons, which reduces the effective nuclear charge experienced by the outermost electron.
- The net effect is that the sum of the first three ionization enthalpies considerably decreases as we move from boron to aluminum.

In conclusion, the sum of the first three ionization enthalpies considerably decreases as we move from boron to aluminum in the p-block elements. This is due to the combined effects of increased atomic radius and the shielding effect of inner electrons, which reduce the effective nuclear charge experienced by the outermost electron.

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