Question

Among Li, Be, N and F, the element having the largest atomic radius is
A. Li
B. Be
C. N
D. F

Answer 1

Hint: Atomic radius depends upon the number of shells the element is having. This can be figured out from knowing the atomic number of the element.

Complete step-by-step answer:
The atomic radius of a chemical element is a measure of the size of the atom, usually the mean or typical distance from the centre of the nucleus to the boundary of the surrounding shells of electrons.
The elements belonging to one group experience an increase in atomic number which results in decrease in atomic radius.
So Li has the largest atomic radius. Therefore the correct option is Option A.

Atomic radius decreases with increase in the atomic number because of the increase in the number of protons. Therefore there is a great attraction between the protons and electrons because of the opposite charges, which attract each other and the protons create a stronger charge.

The atomic radius of Li is : 182pm
The atomic radius of Be is : 112pm
The atomic radius of N is : 155pm
The atomic radius of F is : 147pm

So the correct order of atomic radius as per the mentioned options is :
Be < F < N < Li

The atomic number of each of the elements mentioned are :
Lithium : 3
Beryllium : 4
Nitrogen : 7
Fluorine : 9

Note: Atomic size gradually decreases from left to right across a period of elements this is because within a period of family of elements all electrons are added to the same shell. The valence electrons are held closer towards the nucleus of the atom as a result the atomic radius decreases.