Periodic Table is supposed to covey the major valence shell groups. They
are s-orbitals (red), p-orbitals (green), d-orbitals (blue), and
f-orbitals (purple). There is also one light blue square for lanthanum.
While lanthanum is formally a d-block metal, its chemistry and
reactivity is very similar to f-block metals. Furthermore, the first row
of f-block metals (rare earth metals) are known as lanthanoids, due to
their similar chemistry. As such, lanthanum is given a special box to
denote its borderline behaviour. Also, the last six elements in the
seventh row [Rutherfordium (104) – Meitnerium (109)] have not been given
any formal designation.
will cover the s-orbitals, p-orbitals, d-orbitals, and their applications in Molecular Orbital
Introduction to Quantum Chemistry