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Assertion : Ionic radius of Na^+ is sm...

Assertion : Ionic radius of `Na^+` is smaller than Na Reason : Effective nuclear charge of `Na^+` is higher than Na

A

If both Assertion & Reason are true and the reason is the correct explanation of the assertion.

B

If both Assertion & Reason are true but the reason is not the correct explanation of the assertion.

C

If Assertion is true statement but Reason is false.

D

If both Assertion and Reason are false statements.

Text Solution

AI Generated Solution

The correct Answer is:
To solve the assertion and reason question, we will analyze both the assertion and the reason step by step. ### Step 1: Understanding the Assertion The assertion states that the ionic radius of \( \text{Na}^+ \) is smaller than that of \( \text{Na} \). - **Explanation**: - Sodium (Na) has an atomic number of 11, which means it has 11 protons and 11 electrons. Its electron configuration is \( 1s^2, 2s^2, 2p^6, 3s^1 \). - When sodium loses one electron to form \( \text{Na}^+ \), it loses the outermost electron (3s electron), resulting in an electron configuration of \( 1s^2, 2s^2, 2p^6 \) for \( \text{Na}^+ \). - Thus, \( \text{Na}^+ \) has 11 protons but only 10 electrons. ### Step 2: Understanding the Reason The reason states that the effective nuclear charge of \( \text{Na}^+ \) is higher than that of \( \text{Na} \). - **Explanation**: - Effective nuclear charge (Z_eff) is the net positive charge experienced by an electron in a multi-electron atom. It is calculated as the total number of protons minus the shielding effect of the inner electrons. - In the case of sodium (Na), there are 11 protons and 11 electrons, so the effective nuclear charge is lower due to the shielding effect. - For \( \text{Na}^+ \), there are still 11 protons, but now only 10 electrons are present. This means there is less electron-electron repulsion and more attraction from the protons, resulting in a higher effective nuclear charge. ### Step 3: Conclusion Since \( \text{Na}^+ \) has a higher effective nuclear charge than Na, it attracts its electrons more strongly, leading to a smaller ionic radius. - **Final Statement**: - The assertion is correct: the ionic radius of \( \text{Na}^+ \) is indeed smaller than that of \( \text{Na} \). - The reason is also correct: the effective nuclear charge of \( \text{Na}^+ \) is higher than that of Na. ### Answer Both the assertion and the reason are correct.
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Knowledge Check

  • Assertion: The atomic radii of calcium is smaller than sodium Reason: Calcuim has a lower nuclear charge than sodium.

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