We know that there are 109 elements. He found that the square route of the emission frequency was proportional to the atomic number of many known elements. He was then able to rapidly determine the atomic number of many more elements. They were subsequently discovered. - allowed chemists to show that properties depended on atomic number rather than atomic weight. Continuing to fill the Periodic Table, the electron configuration changes as well.
Nonmetals are at the right of the Table.
They tend to be insulators and react easily with metals. Atomic size varies for a given atom depending on how one measures and the state the atom exists in. This varies if the atoms in question are covalently bonded, ionically bonded, or held together by metallic bonds or dispersive interactions. I 1 is used to represent the energy change upon loss of the first electron. In short, the representative elements tend to gain or lose electrons until they become isoelectronic with the nearest Noble Gas.