Question

What is the valency of fluorine atoms?
(a). 7
(b). 1
(c). 3
(d). 6

Answer 1

- .Hint: Count the number of valence electrons (electrons in the outermost shell) of fluorine. The atomic number of Fluorine is 9.

Complete step by step answer:
According to IUPAC, valency is defined as “the maximum number of univalent atoms (originally hydrogen or chlorine atoms) that may combine with an atom of the element under consideration, or with a fragment, or with a fragment, or for which an atom of this element can be substituted”.
In a nutshell, we can say that valency is a parameter to measure the ability of an atom or element to form a molecule or compound. It can also be defined as the number of bonds the element can form in a compound. Valency, unlike oxidation number, has no sign.
The electronic configuration of fluorine (atomic number = 9) is:
$$1s^{2}2s^{2}2p^5$$$$$$
From the electronic configuration given above, we can see that the valence orbital (2p), needs only one electron to complete its octet.
Therefore, the valency of fluorine atoms is 1, it is univalent.
Hence, the answer is option (b).
Additional Information:
We can also find the valency of an element by using the formula –
Valency = 8 – (number of valence electrons in the element)
In this case,
Valency = 8 – 7 = 1.

Note: Do not confuse between oxidation number and valency. Valency has no charge. Valency is the number of electrons required to complete its octet. Whereas, oxidation number is the charge of an element, either independently, or in a compound.
Valency of fluorine is 1, whereas oxidation number of fluorine is -1.