The periodic table arranges all the ... Well, sodium is below lithium in group one and the reactivity of the alkali metals increases as you go down the group, so potassium is even more reactive.

Mrs Roberts: At its simplest, the periodic table is all the different elements arranged together in a chart. A Russian scientist called Dmitri Mendeleev produced one of the first practical ...

Our bodies require other elements, including non-metal elements such as phosphorus (P), sulphur (S) and chlorine (Cl), and metal elements like potassium ... one-quarter of the periodic table ...