8. Consider the element Scandium, atomic # 21. (a) If the electronic configuration of the element were constructed "from scratch", into which

orbital (and into which shell) would the final electron be placed? (1)

(b) When scandium forms an ion with a charge of +1, from which orbital (and from which

shell) would the electron be removed? (1)

Explanation:

Scandium has atomic number of 21. This means that in it's neutral state its going to have 21 electrons.

a) The full electronic configuration is given as;

1s2 2s2 2p6 3s2 3p6 3d1 4s2

The final electron is placed in the d orbital. The shell is 3d

(b) When scandium has a charge if +1, it has lost an electron. The total number of electrons would now be 21-1 = 20

The electronic configuration would be given as;

1s2 2s2 2p6 3s2 3p6 4s2

The electron in the 3d orbital would be removed.

there are two significant figures.