Atomic Models - Discovery Of The Proton

The English scientist Henry Gwyn Jeffreys Moseley (1887–1915) soon solved the mystery of nuclear charge determining the properties of the atom. Moseley discovered in 1913 that each element contains a unique positive charge in its nucleus. The nucleus of the atom must contain positively charged particles, called protons. Therefore, the amount of charge, or the number of protons, in its nucleus determines an element's identity. The number of protons in the nucleus is called the atomic number. Moseley asserted that the periodic table should be arranged in order of increasing atomic number instead of increasing atomic mass. This arrangement allowed for a complete periodic table, with correct predictions of where new elements were yet to be discovered.