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 ...

It's what makes one element different from another. The number of protons in an atom is called its atomic ... first shell.The remaining 6 electrons will go into the second shell. The electronic ...