Elements are arranged in the periodic table in order of increasing atomic number. For example hydrogen has the atomic number of one, helium two, lithium three etc. The first energy level (the one ...

Chemistry’s eye-catching arrangement of elements has undergone many changes since its inception in the mid 1800s. To this day, scientists seek to improve it. Anyone who attended a high school science ...

It is an icon of natural science and hangs in most chemistry classrooms: the periodic table of elements, which is celebrating its 150th birthday this year. The tabular overview is closely linked to ...