For elements in the first three periods of the periodic table (hydrogen - argon), the orbitals can simply be filled up by increasing energy energy level. A difficulty arises when we come to potassium.

A further quandry arises when we examine the ionisation energies of the d-block elements. We find that it is the 4s orbital electrons that are ionised first before the 3d orbitals. We have to conclude ...

Bismuth is in Group 15 of the periodic table. The s, d and f orbitals are all full, but the p orbitals contain three out of a ...

they are found in 6 th period in periodic table. At room temperature ... (b) It has completely filled s-and p-orbitals and a partially filled d-orbital. (c) It has completely filled s-and p ...