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Ionisation enthalpy of group 15 elements...

Ionisation enthalpy of group 15 elements
I. decrease down the group due to the gradual increase in atomic size.
II. It is higher than that of group 14 elements in the corresponding periods.
III. the order of successive ionisation enthalpies is `Delta_lH_1 lt Delta_lH_2 lt Delta_lH_3`
Which of these statements is`//`are true ? Choose the correct option.

A

I and II

B

II and III

C

I and III

D

All of these

Text Solution

AI Generated Solution

The correct Answer is:
To determine the truth of the statements regarding the ionization enthalpy of group 15 elements, let's analyze each statement step by step. ### Step 1: Analyze the first statement **Statement I:** "Ionisation enthalpy of group 15 elements decreases down the group due to the gradual increase in atomic size." - **Explanation:** As we move down the group in the periodic table, the atomic size increases because additional electron shells are added. A larger atomic size means that the outermost electrons are further from the nucleus and experience less effective nuclear charge. This makes it easier to remove an electron, thus decreasing ionization enthalpy. - **Conclusion:** This statement is **true**. ### Step 2: Analyze the second statement **Statement II:** "It is higher than that of group 14 elements in the corresponding periods." - **Explanation:** Group 15 elements have one more electron in their outer shell compared to group 14 elements. The presence of a half-filled p-orbital (in group 15) provides extra stability, making it harder to remove an electron compared to group 14. Therefore, the ionization enthalpy of group 15 elements is indeed higher than that of group 14 elements in the same period. - **Conclusion:** This statement is **true**. ### Step 3: Analyze the third statement **Statement III:** "The order of successive ionisation enthalpies is ΔlH₁ < ΔlH₂ < ΔlH₃." - **Explanation:** The first ionization enthalpy (ΔlH₁) is the energy required to remove the first electron. Once the first electron is removed, the remaining atom becomes positively charged, which increases the effective nuclear charge experienced by the next electron to be removed. Thus, the second ionization enthalpy (ΔlH₂) is greater than the first, and similarly, the third ionization enthalpy (ΔlH₃) is greater than the second. Therefore, the order ΔlH₁ < ΔlH₂ < ΔlH₃ holds true. - **Conclusion:** This statement is **true**. ### Final Conclusion All three statements are true. Therefore, the correct answer is that all of these statements are true.
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