The correct identification of the characteristics of the
C2 molecule can be established by analyzing the electronic configuration and bond formation of the carbon atoms involved. Each carbon in
C2 contributes two electrons to the molecular orbitals.
To evaluate the available options:
Option A: Suggests a bond order of 2, stating the molecule is paramagnetic with one sigma and one pi bond.
Option B: Claims a bond order of 0 and deems
C2 non-existent.
Option C: Indicates a bond order of 2, labeling it as diamagnetic with both bonds being pi bonds.
Option D: Proposes a bond order of 1.5 with paramagnetic nature; states both bonds formed are sigma bonds.
The bonding in dioxygen can be analyzed via Molecular Orbital Theory (MOT). In the molecular orbital configuration of
C2, which comprises 2 carbon atoms each having 2 electrons in the valence p orbital (a total of 4 electrons), the molecular orbital filling is as follows:
Firstly, electrons fill the lowest energy
σ2s, followed by
σ2s′*,π2px, and
Ï€2py (which are degenerate) and finally
σ2pz. Each of these
Ï€ orbitals (from
Ï€2pz and
Ï€2py ) would ideally accommodate 2 electrons, one from each carbon atom.
The bond order is calculated by the formula:
Bond Order
In
C2, assuming each carbon atom initially has one electron in each
Ï€2px and one in
Ï€2py with none in the
σ2pz due to higher energy level at initial stage,
Bond Order
This indicates two pi bonds are formed and no sigma bond.
Furthermore, the presence of unpaired electrons in the molecular orbitals renders the molecule paramagnetic.
Analysis: Although Option A correctly states the bond order and the paramagnetic nature, it incorrectly assigns the bond types (stating one sigma and one pi bond). Conversely, Option C precisely asserts the two pi bonds but incorrectly labels the molecule as diamagnetic. Thus, the closest correct option, despite the error in magnetic character, is:
Option C: Bond order
=2.0;‌‌ Diamagnetic in nature; Both bonds formed are pi bonds.
It accurately comments on the bond order and the configurations but errs in the magnetic property;
C2 is indeed paramagnetic, not diamagnetic as mentioned in Option
C.