Question

Why is the covalency of the carbon in the CO molecule three?
A. An unexcited carbon has two unpaired electrons
B. The carbon atom can be acceptor of an electron pair
C. The carbon has four valence electrons
D. Maximum covalency of carbon is three

Answer 1

Hint: The covalency can be defined as the number of bons an element forms with the other elements o in the molecule. Valency is the number of electrons lost or gained to achieve the stable electronic configuration. Therefore, valency and covalency both are different from each other. Covalency depends upon the valency.

Complete Step by step answer: First of all, we have to draw the Lewis structure so that we get the number of bonds the carbon forms with the oxygen, that is, covalency.
So, to draw the Lewis structure –
-In the molecule, find the number of valence electrons of each of the atoms present in that molecule.
-The number of valence electrons is usually the same as the group number where the element is located.
-So, we know that the number of valence electrons of carbon is 4 and the number of valence electrons of oxygen is 6.
-Calculate the total number of valence electrons in the molecule, so:
Total valence electrons = valence electrons of carbon + valence electrons of oxygen $ = 4 + 6 = 10$ electrons
-Find the number of octet electrons by using the octet rule. So, the carbon and oxygen should have eight electrons.
-Then, place the valence electrons around each atom and draw the bonds for each pair of electrons.
Hence, caron forms three covalent bonds with the oxygen using the triple bond because carbon can be the acceptor electron pairs. Therefore, there are two covalent bonds and another one is coordinate covalent bond.

Hence, the correct option is (B).

Note: Carbon has the four valence electrons. So, it should either gain or lose the electrons to make the configuration stable. It has the ability of both gaining and losing the electrons. So, that’s why the formation of the coordinate covalent bond takes place between carbon and oxygen, thereby forming the triple bond in the CO molecule.