Question

Starting with the previous noble gas, write the condensed gound-state electron configuration of an atom of the following element. (Type your answer using the format [Ar] 3d10 4s2) Please explain.

a) nickel

b)hafnium

c) scandium

d) arsenic

Answer 1

The ground-state electronic configuration of every element contains the no.of electrons as the element's atomic number. The order for filling up orbitals is governed by Aufbau's Principle, Hund's rule of maximum spin multiplicity and giving preference to higher stability by preferring half-filled or fully filled orbitals to configurations that contains orbitals that are neither fully filled nor half-filled. Generally, the method of expressing electronic configurations is by representing the nearest previous noble gas followed by the extra electrons that the element contains.

a) Ni has an atomic number of 28 giving it the electronic configuration of [Ar] 3d⁸4s². If one were to make it such that the 3d orbital had 9 electrons and the 4s one, it would still lead to a configuration of similar stability. But it has been experimentally determined that the 4s orbital of Ni is fully filled.

b) The atomic number of Hf is 72. It is the first element after the lanthanide series and so contains a fully filled f-orbital. Its electronic configuration is [Xe] 4f¹⁴ 5d² 6s². From Ar, its configuration becomes [Ar] 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s² 5p⁶ 4f¹⁴ 5d² 6s².

c) Sc's atomic number is 21 giving it 21 electrons. Its previous noble gas Ar contains 18 electrons and the remaining three electrons are arranged in the 3d and 4s orbitals as 3d¹4s² giving it the configuration [Ar] 3d¹4s².

d) As's atomic number is 33. It is a p-block element whose valence shell is similar to that of N and P. Taking into account its nearest previous noble gas Ar, its electronic configuration is [Ar] 3d¹⁰ 4s² 4p³.