Full Name: Henry Gwyn Jeffreys Moseley
Place of Birth: Weymouth, Dorset
Date of Birth and Death: 23 November 1887 and 10 August 1915
Work Done: He had justified physical laws of the previous empirical and chemical concept of the atomic number and justified many concepts in chemistry by sorting the chemical elements of the Periodic Table of the Elements in a quite logical order based on their physics. Moseley showed that there were gaps in the atomic number sequence at numbers 43, 61, 72, and 75, and gave very strong evidence that there were no other gaps in the Periodic Table between the elements aluminium (atomic number 13) and gold (atomic number 79).
His Contribution: 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. His experimental set of data showed that with a positively-charged nucleus surrounded by negatively-charged electrons, the atomic number is understood to be the exactly physical number of positive charges (later discovered and called protons) in the central atomic nuclei of the elements.
Technology Available: X-ray Spectrometers
Relevance to Today: He gave very strong evidence that there were no other gaps in the Periodic Table between the elements aluminium (atomic number 13) and gold (atomic number 79). Also, he stated that a positively-charged nucleus surrounded by negatively-charged electrons in which the atomic number is understood to be the exactly physical number of positive charges, which we use now.
Source: http://en.wikipedia.org/wiki/Henry_Moseley
Shao Xuan
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