There are lots of different substances but only just over a hundred elements. An element is a substance that is made up of only one kind of atom. The atoms in a particular element are the same as each ...

Chemical reactions occur when elements or compounds combine and create new compounds. Elements are substances that contain only one type of atom and are represented by unique symbols on the periodic ...

Atoms are the building blocks of everything. Atoms can form strong bonds with each other, making molecules. Symbols and formulae Letters from the alphabet are used to represent chemical elements. An ...

The need for a physical constant quantifying a reference amount of substance is a manifestation of the atomic nature of matter. At the basis of the concept of a 'quantity constant' lies the law of ...