Polonium has no biological role and any sample used to kill the former KGB spy must have come from either a research laboratory or nuclear facility. It is found in uranium ores but at miniscule levels 0.00000001%. So small that the Curie's were awarded the Nobel prize for their superhuman effort to extract it. Could a terrorist smuggle Polonium into this country or is there a human leak at a UK Defence Establishment? Gramme quantities of polonium-210 are synthesized from bismuth in nuclear reactors. Carrying quantities of polonium is difficult because of the high temperature from radioactive decay [500oC] and the emission of deadly alpha particles. These radioactive particles are most dangerous when ingested. They pick up electrons from cells in the body and escape as helium gas. Polonium-210 has a relatively short half life [138 days] so the 'evidence' diminishes constantly with time. Also Polonium is fairly volatile and will evaporate if not kept in a sealed container. Polonium is one of the deadliest known substances and is believed to be a trillion more times toxic than HCN weight for weight.

In the standard form of the periodic table the s-block, p-block, and d-block elements are organised into 18 vertical columns called groups. These are labelled from 1 to 18 under current IUPAC numenclature.

Earlier labelling schemes (Trivial Group names)

For historical reasons some Groups have special names. Terms such as the "alkali metals" are in very common use whereas the term "pnictogens" is very much less common. Some of these special names are listed in the Table.

In addition the elements 57-71 (lanthanum-lutetium) are referred to as the actinoids (actinides) and the elements 89-103 (actinium-lawrencium) are referred to as the actinoids (actinides). The elements Sc, Y, and the lanthanoids are sometimes referred to as the rare earths.