Question

For elements B, C, N, Li, Be, O and F, the correct order of first ionization enthalpy is:

• A. \(\text{B<Li<Be<C<O<N<F} \)
• B. \(\text{Li<C<B<O<N<F} \)
• C. \(\text{Li<C<B<O<N<F} \)
• D. \(\text{Li<B<C<O<N<F}\)

Hint:

The first ionization enthalpy increases from left to right in a period due to an increase in nuclear charge and decreases down a group due to the increased size of atoms.

Answer 1

The Correct Option is C

To determine the correct order of first ionization enthalpy for the elements B, C, N, Li, Be, O, and F, we need to understand the factors that influence ionization energy. Ionization energy is the energy required to remove an electron from an atom in its gaseous state. The order of ionization energy generally increases across a period from left to right in the periodic table, due to increased nuclear charge with minimal shielding effect by inner electrons. 

The elements in question are from the second period of the periodic table (Li, Be, B, C, N, O, and F). Their general order in terms of increasing atomic number is Li < Be < B < C < N < O < F. Let's analyze the order of ionization energy:

1. Lithium (Li): Being the first element in the second period, it has the lowest ionization energy due to minimal nuclear charge and the single outer electron.
2. Beryllium (Be): Higher ionization energy than Li because it has a full 2s subshell, which is relatively stable.
3. Boron (B): Its first electron needs to be removed from the p-orbital, which requires slightly less energy than removing a second s-electron as in Be, thus Li < B < Be.
4. Carbon (C): Higher ionization energy than B because of increased nuclear charge and electrons in the same shell.
5. Nitrogen (N): Has a half-filled stable p-subshell, which results in a slightly higher ionization energy compared to oxygen.
6. Oxygen (O): Slightly lower ionization energy compared to N due to inter-electronic repulsion in the partially filled p-orbital.
7. Fluorine (F): Highest among these due to its high effective nuclear charge and need to complete its outer shell.

Considering these points, the correct order of first ionization enthalpy is:

\(\text{Li < B < Be < C < O < N < F}\)

However, among the provided options, both (b) and (c) list the same order which seems to be incorrect, because they don't match the general logic we derived. The correct prediction should be:

• The pattern effective according to theoretical principles in chemistry suggests the increasing ionization enthalpy order as \(\text{Li < B < Be < C < O < N < F}\) which unfortunately is not among provided solution options, but these identify error recognition capabilities for correction.