Question

Which is correct?

Choose one answer.

	A. Ne has a larger radius than Li because Ne has more electrons.
	B. Ne has a larger radius than Li because Ne has a full shell configuration.
	C. Ne has a smaller radius than Li because Ne is a monatomic noble gas.
	D. Ne has a smaller radius than Li because Ne has a larger effective nuclear charge.

Answer 1

We know Lithium is an element of group 1 in period 2 while Ne is placed in group 18 in the same period. Both Li and Ne are in the same period and thus have the same number of energy levels.

We know the atomic number of Li is 3 so it has 3 protons in the nucleus while the atomic number of Ne is10 so Ne having 10 protons in the nucleus .
Also we know smaller the nuclear charge , lager the size. Since Li having less nuclear charge than Ne so pulls the electrons toward the nucleus less than Ne.

Correct option will be (D)