Question

Arrange the following elements in increasing order of first ionization enthalpy:
Li, Be, B, C, N
Choose the correct answer from the options given below:

• A. Li < Be < B < C < N
• B. Li < B < Be < C < N
• C. Li < Be < C < B < N
• D. Li < Be < N < B < C

Answer 1

The Correct Option is B

Arrange the following elements in increasing order of first ionization enthalpy: Li, Be, B, C, N

Choose the correct answer from the options given below:

Ionization enthalpy generally increases across a period from left to right. However, there are exceptions due to electronic configurations.

1. Lithium (Li): It has the lowest ionization enthalpy as it readily loses one electron to achieve a stable noble gas configuration.

2. Boron (B): Boron has a slightly lower ionization enthalpy than beryllium because removing a p-electron from boron is easier than removing an s-electron from the filled s-orbital of beryllium.

3. Beryllium (Be): Beryllium has a higher ionization enthalpy than lithium due to its smaller size and higher effective nuclear charge. Also it has a completely filled 2s orbital.

4. Carbon (C): Carbon has a higher ionization enthalpy than boron due to its increased nuclear charge and smaller atomic radius.

5. Nitrogen (N): Nitrogen has an exceptionally high ionization enthalpy because it has a half-filled p-orbital configuration (2p³), which is particularly stable. Removing an electron disrupts this stable configuration.

Therefore, the increasing order of first ionization enthalpy is:

Li < B < Be < C < N

Conclusion:

The correct order is Li < B < Be < C < N