The periodic table of chemical elements, often called the periodic table, organizes all discovered chemical elements in rows (called periods) and columns (called groups) according to increasing atomic ...

Beyond the fact that the radio-elements were in present course of evolution, it added little to the conceptions of chemistry. But in the second and more recent phase—concerned with the chemical ...

Everything we can see and touch, and quite a lot that we can’t as well, is made of tiny particles called atoms. Some substances, like particles of this iron, contain only one kind of atom.