And generations of children have sung the words, "hydrogen and helium, lithium, beryllium..." in an attempt to memorise some of the 118 elements. This year, the periodic table of chemical elements ...

Going down group 1, the melting point decreases. Lithium, Li Fizzes steadily; slowly becomes smaller until it disappears Sodium, Na Fizzes rapidly; melts to form a ball; quickly becomes smaller ...

They include lithium, sodium and potassium, and are placed in the first vertical column on the left of the periodic table. All the Group 1 elements are very reactive, and all react with water to ...