Moseley's Contribution To Our Understanding of The Atom
Before Moseley and his law, atomic numbers had been thought of as a semi-arbitrary ordering number, vaguely increasing with atomic weight but not strictly defined by it. Moseley's discovery showed that atomic numbers were not arbitrarily assigned, but rather, they have a strong physical basis. Moseley redefined the idea of atomic numbers from its previous status as an ad hoc numerical tag to help sorting the elements, in particular in the Periodic Table, into a real and objective whole-number quantity that was experimentally measurable. Furthermore, as noted by Bohr, Moseley's law provided a reasonably complete experimental set of data that supported the (new from 1911) conception by Ernest Rutherford and Antonius Van den Broek of the atom, with a positively-charged nucleus surrounded by negatively-charged electrons in which the atomic number is understood to be the exact physical number of positive charges (later discovered and called protons) in the central atomic nuclei of the elements. Moseley mentioned the two scientists above in his research paper, but he did not actually mention Bohr, who was rather new on the scene then. Simple modification of Rydberg's and Bohr's formulas were found to give theoretical justification for Moseley's empirically-derived law for determining atomic numbers.
Read more about this topic: Henry Moseley
Famous quotes containing the words contribution and/or atom:
“If melodrama is the quintessence of drama, farce is the quintessence of theatre. Melodrama is written. A moving image of the world is provided by a writer. Farce is acted. The writer’s contribution seems not only absorbed but translated.... One cannot imagine melodrama being improvised. The improvised drama was pre-eminently farce.”
—Eric Bentley (b. 1916)
“He bends to the order of the seasons, the weather, the soils and crops, as the sails of a ship bend to the wind. He represents continuous hard labor, year in, year out, and small gains. He is a slow person, timed to Nature, and not to city watches. He takes the pace of seasons, plants and chemistry. Nature never hurries: atom by atom, little by little, she achieves her work.”
—Ralph Waldo Emerson (1803–1882)