Chemical Sciences: A Manual for CSIR-UGC National Eligibility Test for Lectureship and JRF/Whole number rule

From Wikibooks, open books for an open world
Jump to navigation Jump to search

The Whole Number Rule states that the masses of the elements are whole number multiples of the mass of the hydrogen atom.[1] The rule can be formulated from Prout's hypothesis put forth in 1815.[2] In 1920, Francis W. Aston demonstrated through the use of a mass spectrometer that apparent deviations from the rule are predominantly due to the existence of isotopes;[3] they are secondarily due to binding energy, as mass defect. The modern form of the whole number rule is that the atomic mass of a given isotope is approximately the mass number (number of protons plus neutrons) times an atomic mass unit (approximate mass of a proton, neutron, or hydrogen-1 atom).

References[edit | edit source]

  1. Budzikiewicz H, Grigsby RD (2006). "Mass spectrometry and isotopes: a century of research and discussion". Mass spectrometry reviews. 25 (1): 146–57. doi:10.1002/mas.20061. PMID 16134128.
  2. Prout, William (1815). "On the relation between the specific gravities of bodies in their gaseous state and the weights of their atoms". Annals of Philosophy. 6: 321–330. Retrieved 2007-09-08. {{cite journal}}: Cite has empty unknown parameter: |coauthors= (help)
  3. Aston, Francis W. (1920). "The constitution of atmospheric neon". Philosophical Magazine. 39 (6): 449–455. {{cite journal}}: |access-date= requires |url= (help); Cite has empty unknown parameter: |coauthors= (help)

Harkins WD (1925). "The Separation of Chlorine into Isotopes (Isotopic Elements) and the Whole Number Rule for Atomic Weights". Proc. Natl. Acad. Sci. U.S.A. 11 (10): 624–8. doi:10.1073/pnas.11.10.624. PMC 1086175. PMID 16587053.