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Assertion: (A) Generally, ionsiation ent...

Assertion: (A) Generally, ionsiation enthalpy increases from left to right in a period.
Reason ( R) When successive electrons are added to the orbitals in the same principle quantum level, the shielding effect of inner core of electrons does not increase very much to compensate for the increased attraction of the electrons to the nucleus.

A

Assertion is correct statement and reason is wrong statement.

B

Assertion and reason both are correct statements and reason is correct explanation of Assertion.

C

Assertion and reason both are wrong statements.

D

Assertion and wrong statements and reason is correct statements.

Text Solution

AI Generated Solution

The correct Answer is:
### Step-by-Step Solution: 1. **Understanding the Assertion**: - The assertion states that ionization enthalpy generally increases from left to right in a period. This is a well-established trend in the periodic table. 2. **Analyzing the Trend**: - As we move from left to right across a period, we are adding protons to the nucleus and electrons to the same principal energy level. The increase in nuclear charge (more protons) leads to a stronger attraction between the nucleus and the electrons. 3. **Shielding Effect**: - The reason provided states that when successive electrons are added to the orbitals in the same principal quantum level, the shielding effect of inner core electrons does not increase significantly. This is true because no new inner shells are being added as we move across a period. 4. **Conclusion on Assertion and Reason**: - Since the assertion is true (ionization enthalpy increases from left to right) and the reason correctly explains why this trend occurs (the minimal increase in shielding effect), we conclude that both the assertion and reason are true, and the reason is the correct explanation of the assertion. 5. **Final Answer**: - Therefore, the correct option is that both the assertion and reason are true, and the reason is the correct explanation of the assertion.
### Step-by-Step Solution: 1. **Understanding the Assertion**: - The assertion states that ionization enthalpy generally increases from left to right in a period. This is a well-established trend in the periodic table. 2. **Analyzing the Trend**: - As we move from left to right across a period, we are adding protons to the nucleus and electrons to the same principal energy level. The increase in nuclear charge (more protons) leads to a stronger attraction between the nucleus and the electrons. ...
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Assertion: Boron has a smaller first ionisation enthalpy than beryllium. Reason: The penetration of a 2s electron to the nucleus is more than the 2p electron, hence 2p electorn is more shielded by the inner core of electrons than the 2s electrons.

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Knowledge Check

  • Assertion: Shielding effect increases as we go down the group. Reason: More is the number of electrons in the penultimate shell, more is shielding.

    A
    If both assertion and reason is the correct explanation of assertion.
    B
    If both assertion and reason is the correct explanation of assertion.
    C
    If both assertion and reason is the correct explanation of assertion.
    D
    If both assertion and reason is the correct explanation of assertion.

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    Assertion: Electron gain enthalpy always becomes less negative as we go down a group in Modern periodic table. Reason: The size of the atom increase on going down the group in Modern periodic table and the added electron would be farther from the nucleus.

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    The periodicity is related to the electronic configuration. That is, all chemical and physical properties are a manifestation of the electronic configuration of the elements. The atomic and ionic radii generally decrease in a period from left to right. As a consequence, the ionization enthalpies generally increase and electron gain enthalpies become more negative across a period. In other words, the ionization enthalpy of the exterme left element in a period is the least and teh electron gain enthalpy of the element on the exterme right is the highest negative. This results into high chemical reactivity at the two extermes and the lowest in he centre. Similarly down the group, the increase in atomic and ionic radii result in gradual decrease in ionization enthalpies and a regular decrease (with exception in some third period elements) in electron gain enthalpies in the case of main group elements. The loss and gain of electrons can be co-related with the reducting and oxidising behaviour, and also with metallic and non-metallic character respectively, of the elements. The correct order of the metallic character is:

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