and atomic radius. Many scientists worked on the problem of organizing the elements, but Dmitri Mendeleev published his first version of the periodic table in 1869, and is most often credited as its ...

Elements are arranged in the periodic table in order of increasing atomic number ... up to a maximum of 8 electrons (only true for the first 20 elements). Example: sodium has the electron ...

Chemists use symbols and formulae to represent elements and compounds ... The method chosen depends on the type of mixture. Atomic structure - AQA Atoms consist of a nucleus containing protons ...