A necessary prerequisite for constructing the periodic table was the individual discovery of chemical elements. Although elements such as gold (Au), silver (Ag), tin (Sn), copper (Cu), lead (Pb), and mercury (Hg) were known since ancient times, the first scientific discovery of an element occurred in 1669, when the alchemist Henning Brand discovered phosphorus. Over the following 200 years, chemists acquired a substantial amount of knowledge about the properties of elements and their compounds. As the number of discovered elements grew, scientists began investigating models to recognize properties and develop classification schemes. The first classification was the division of elements into metals and non-metals, allowing the prediction of other elements' properties and determining whether they would be metallic or non-metallic.