Question

Valency of the elements in the halogen ground is _____
a.) One
b.) Two
c.) Three
d.) Four

Answer 1

Before attempting this question, one should have prior knowledge about the elements belong to halogen group and also remember that valency is the total numbers of electrons an atom of element uses in the combination with other elements atom, using this information will help you to approach the solution of the question.

Complete step by step answer:
Before approaching towards the answer let’s discuss about the valency which can be explained as the maximum electrons used by the atom of an element during the combination with the other element’s atom
We know that halogen elements are fluorine (F), chlorine (Cl), Bromine (Br), Iodine (I) and Astatine (At)
Since the electronic configuration of each element is given as;
Fluorine (F) = 2, 7
Chlorine (Cl) = 2, 8, 7
Bromine (Br) = 2, 8, 18, 7
Iodine (I) = 2, 8, 18, 18, 7
Astatine (At) = 2, 8, 18, 32, 18, 7

Since each element consists of 7 electrons in outermost shell because of which all the element from halogen group have tendency to accept one electron to obtain configuration as noble gas
Therefore, valency of the elements in the halogen is one.
So, the correct answer is “Option A”.

Note: In the above solution we came across the halogen group which is also named as the group 17 which is one of the parts of periodic table which is the arrangement of elements from lowest atomic number to highest atomic number where group 17 consist of 5 elements where the order of melting point increase from fluorine to Astatine, boiling point increase from fluorine to Astatine, electronegativity decreases moving from fluorine to Astatine, etc.