Question

Which member of each of the following pairs of atoms/ions has larger radius and why?
a) Li : Na
b) Br : Kr
c) Na : Mg
d) Be : B

Answer 1

Br : Kr has the larger radius among the given pair...
because they are the 4th period elements but others are above 4th period.....we know that going down the periodic table radius of atom increases

Answer 2

Hey dear,

◆ Atomic radius -

- Atomic radius is nothing but the distance of outermost shell from nucleus of the atom.

# Trend of atomic radius in modern periodic table -

- Atomic radius of elements increases as we go down the group.

- Atomic radius of elements decreases from left to right across the period.

◆ Answers -

1) Na > Li

As Na is down in the same group as Li, its atomic radius is larger than Li.

2) Br > Kr

As Kr is next to Br in same period, its atomic radius will be lesser.

3) Na > Mg

As Mg is next to Na in same period, its atomic radius will be less than Na.

4) B > Be

Exceptionally, B has larger atomic radius than Be due to effect of nuclear charge.

Hope this helped you. Thanks for asking..