An introduction to the noble gases and chemical bonding via Lewis theory and the octet rule are common inclusions in secondary school curricula. However, the usual approach may lead to misconceptions and difficulties when valence bond (VB) theory and valence shell electron pair repulsion (VSEPR) theory are taught at a later pre-university stage.…

This article aims to introduce the lanthanides (also known as the lanthanoids) to teachers and their students. The lanthanides are not mere "footnotes" at the bottom of the periodic table but make up a group of interesting and unique metallic elements. They and their compounds have widespread technological applications that have become…