In this video Paul Andersen explains how to write out the electron configuration for atoms on the periodic table. More importantly he shows you why electrons arrange themselves in shells, subshells and orbitals by using Coulomb's law...

An introduction to NMR spectroscopy.

It gives idea about lanthanides such as position, electronic configuration, atomic, ionic size, & their uses.

It explains periodicity in electron gain enthalpy and electronegativity.