Question

The valency of sulphur in $\text{S}{{\text{F}}_{6}}$ is:
(A). -1
(B). -2
(C). +4
(D). +6

Answer 1

- Hint: The combining power of an element with other atoms when it forms chemical compounds or molecules are called valency. It is equal to the number of electrons present in the outer shell of the sulfur element.

Complete step-by-step solution -
As we got to know through hints that the valency of the atom of an element is determined by the number of electrons in its outermost shell, i.e. valence shell. Let us know more about the concept of Valency.
Electrons in an atom are arranged in different orbitals (shells) represented as K, L, M, N and so on. The electrons present in the outermost shell of an atom are called valence electrons. The outermost orbit usually contains more energy than the electrons present in other orbits. That is why,valence electrons take part in any chemical reaction.
Also, for an atom with less than 4 or less than 4 electrons in the valence shell –
Valency = No. of electrons
For atoms with more than 4 valence electrons-
Valency= 8-No. of electrons in its outermost shell
In $\text{S}{{\text{F}}_{6}}$, Sulphur is present in the 3rd group which means it can expand its octet by donating all of its 6 electrons. Hence, it donates all the 6 electrons to each fluoride atom.
Thus, here the valency of sulfur in $\text{S}{{\text{F}}_{6}}$is 6.
Hence, option (D) is the correct answer.

Note: An atom has to gain, lose or share a particular number of electrons from its outermost orbit to obtain complete octet. That is why noble gases are not reactive because their outermost orbit is completely filled which means it has gained its stability.