When we come to classifying elements and exploring different ways to classify them, it can be helpful to recognise that, broadly speaking, we can divide our observations into two separate groups: ...

Group 1 elements react with moist air. They are stored in oil to stop air and water vapour coming into contact with them. Moist air reacts with potassium to form potassium oxide. This creates a ...

The periodic table’s arrangement also allows scientists to discern trends in element properties, including electronegativity, ionization energy, and atomic radius. Many scientists worked on the ...

The group 1 elements react quickly with oxygen in the air at room temperature. Most transition elements react slowly, or not at all, with oxygen at room temperature. Some transition metals react ...

In 'Traite Elementaire de Chimie', Lavoisier listed 33 substances he considered elements, including light and caloric (heat). The next significant step came in 1829 when Johann Wolfgang Dobereiner ...

The periodic table organizes chemical elements based on atomic weight, electron configurations, and chemical properties, ...

And yet, the periodic element, which would come to inherit his name has not wielded such legendary power. Indeed, for decades following promethium’s discovery, its very properties remained unknown.

Soon, Mendeleev was predicting the properties of three elements – gallium, scandium and germanium – that had not then been discovered. So convinced was he of the soundness of his periodic law ...