Question

Arrange the following elements in increasing order of their atomic radii.

$Li,Be,F,N$

• A. $N<F<Be<Li$
• B. $F<N<Li<Be$
• C. $F<Be<N<Li$
• D. $F<N<Be<Li$

Answer 1

The correct option is D $F<N<Be<Li$

In a period as outer most shell remains same and the difference comes only with number of protons that is nuclear charge. As we move from left to right nuclear charge increases this increases the affect of nuclear charge on the outer most shell making radius decrease. Hence, fluorine is at the end in the 2nd period and lithium comes first in this period after lithium, beryllium and then nitrogen.
$F<N<Be<Li$.