Question

Which of these elements is a metal? A. hafnium (Hf) B. radon (Rn) C. silicon (Si) D. sulfur (S) E. selenium (Se)

Answer 1

Answer: Option (A) is the correct answer.

Explanation:

Substances or elements which lose electrons are known as metals whereas elements which gain electrons are known as non-metals.

For example, electronic configuration of hafnium is $[Xe]4f^{14}5d^{2}6s^{2}$. It is a transition metal as it has incompletely filled d-orbital so, it will lose electrons to attain stability.

Electronic configuration of radon is $[Xe]4f^{14}5d^{10}6s^{2}6p^{6}$. Since it is a noble gas it has completely filled orbitals so, it will neither lose nor gain electrons.

Electronic configuration of silicon is $[Ne]3s^{2}3p^{2}$ and it is a non-metal. So, it will gain electrons to complete its octet.

Electronic configuration of sulfur is $[Ne]3s^{2}3p^{4}$ and it is a non-metal. So, it will gain electrons to complete its octet.

Electronic configuration of selenium is $[Ne]3d^{10}4s^{2}4p^{4}$ and it is a non-metals. So, it will gain electrons to complete its octet.

Hence, we can conclude that out of the given options hafnium (Hf) is the element which is a metal.

Answer 2

The answer is A. Hafnium