Covalency of oxygen cannot exceed 2 unlike sulphur which can show +4 o...
Oxygen does not have a d-orbital thereby not exceeding its covalency beyond 2. Whereas sulphur has vacant d-orbitals hence can exceed its covalency to +4 or +6.
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Covalency of oxygen cannot exceed 2 unlike sulphur which can show +4 o...
Answer:
Oxygen atom does not have d-orbitals
The correct answer for why the covalency of oxygen cannot exceed 2 is option A, which states that oxygen atom does not have d-orbitals. This means that the oxygen atom does not have any available d-orbitals to participate in bonding. Let's delve into this explanation further.
Valence shell electronic configuration of oxygen
The atomic number of oxygen is 8, which means it has 8 electrons. The electronic configuration of oxygen is 1s² 2s² 2p⁴. In its valence shell (2s² 2p⁴), there are a total of 6 electrons.
Formation of covalent bonds
Oxygen has a valency of 2, which means it can form 2 covalent bonds. In a covalent bond, two atoms share electrons to achieve a stable electronic configuration. Oxygen has a tendency to gain 2 electrons to complete its octet.
Lack of d-orbitals in oxygen
The d-orbitals are present in the third shell (n=3) and beyond. Oxygen, being in the second period, does not have any d-orbitals. It only has 2s and 2p orbitals available for bonding. Therefore, the covalency of oxygen is limited to a maximum of 2.
Comparison with sulphur
Sulphur, on the other hand, is in the third period and has access to the d-orbitals. Hence, it can exhibit a covalency of 4 or even 6. The electronic configuration of sulphur is 1s² 2s² 2p⁶ 3s² 3p⁴ 3d⁰.
Formation of multiple bonds by oxygen
Although oxygen cannot exceed a covalency of 2, it can form a double bond with another oxygen atom. In this case, oxygen shares two pairs of electrons with another oxygen atom, resulting in a double bond. The double bond helps oxygen achieve a stable electronic configuration.
Limitation due to small size
The small size of the oxygen atom also plays a role in its limited covalency. The small size restricts the possibility of promoting its electrons to higher energy levels, such as the d-orbitals. The promotion of electrons to higher energy levels requires a larger atomic size, which oxygen lacks.
In conclusion, the covalency of oxygen cannot exceed 2 because it does not have d-orbitals available for bonding, and its small size prevents the promotion of electrons to higher energy levels.
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