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

Order the elements Li, Be, B, C, N by increasing first ionization enthalpy. Select the correct option from the choices provided.

Ionization enthalpy generally rises across a period from left to right. However, electronic configurations cause deviations.

1. Lithium (Li): Possesses the lowest ionization enthalpy due to its facile electron loss to attain a stable noble gas configuration.

2. Boron (B): Exhibits a slightly lower ionization enthalpy than beryllium. This is because removing a p-electron from boron is less energy-intensive than removing an s-electron from beryllium's filled s-orbital.

3. Beryllium (Be): Displays a higher ionization enthalpy than lithium, attributable to its smaller size and greater effective nuclear charge. Its fully filled 2s orbital also contributes.

4. Carbon (C): Shows a higher ionization enthalpy than boron, resulting from its increased nuclear charge and reduced atomic radius.

5. Nitrogen (N): Demonstrates an exceptionally high ionization enthalpy due to its stable half-filled p-orbital configuration (2p³). Electron removal disrupts this stability.

Consequently, the elements arranged in ascending order of first ionization enthalpy are:

Li < B < Be < C < N

Final Answer:

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