Which of these elements is a metal? a. hafnium (hf) b. radon (rn) c. silicon (si) d. sulfur (s) e. selenium (se)

The answer is A. Hafnium

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 . 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 . Since it is a noble gas it has completely filled orbitals so, it will neither lose nor gain electrons.

Electronic configuration of silicon is and it is a non-metal. So, it will gain electrons to complete its octet.

Electronic configuration of sulfur is and it is a non-metal. So, it will gain electrons to complete its octet.

Electronic configuration of selenium is 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.

metals are good conductor of electricity. it has free electrons on their surface. according to electron pool theory, each atom present in a metal crystal losses all of its valence electron and as a result a pool of free is form. these pool of electrons are free to move and   conduct electricity easily   while making metal as good conductor.

the correct answer is a. the ability of electrons to flow throughout the metal.

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