IUPAC has launched a new periodic table which emphasises isotopic composition

A new periodic table which emphasises the isotopic composition of the elements has been launched as a teaching resource.

The International Union of Pure and Applied Chemistry (IUPAC) started the project in 2008 and the table was published in July this year.

IUPAC's committee on chemical education felt that periodic tables which provide mean molecular weights may be misleading to some students. The mass number listed for bromine, for example, is generally 79.9, but of course, there is no such thing as 80Br. Instead bromine is composed of the distinct isotopes 79Br and 81Br which exist in roughly a 1:1 ratio.

IUPAC periodic table of the isotopes

Source: © IUPAC

IUPAC have emphasised this in the new teaching aid. A colour coded pie chart showing the abundance of each stable and unstable isotope appears next to the symbol for each element. The elements themselves are also colour coded depending on whether they have one, two, several or no stable isotopes. Students can see the isotopic make up of any given element at a glance.

A copy of the table can be downloaded free of charge from the CIAAW website.