This MedLibrary.org supplementary page on Prout's hypothesis is provided directly from the open source Wikipedia as a service to our readers. Please see the note below on authorship of this content, as well as the Wikipedia usage guidelines. To search for other content from our encyclopedia supplement, please use the form below:
Related Sponsors
Prout's hypothesis was an early 19th century attempt to explain the existence of the various chemical elements through a hypothesis regarding the internal structure of the atom. In 18151 and 1816,2 the English chemist William Prout published two papers in which he observed that the atomic weights that had been measured for the elements known at that time appeared to be whole multiples of the atomic weight of hydrogen. He then hypothesized that the hydrogen atom was the only truly fundamental object, and that the atoms of other elements were actually groupings of various numbers of hydrogen atoms.
Contents |
Influence
Prout's hypothesis remained influential in chemistry throughout the 1820s. However, more careful measurements of the atomic weights, such as those compiled by Jöns Jakob Berzelius in 1828 or Edward Turner in 1832, "disproved" the hypothesis. In particular the atomic weight of chlorine, which is 35.45 times that of hydrogen, could not at the time be explained in terms of Prout's hypothesis. Some came up with the ad hoc claim that the basic unit was one-half of a hydrogen atom, but further discrepancies surfaced. This resulted in hypothesis that one-quarter of a hydrogen atom was the common unit. Although these turn out to be wrong, these conjectures catalyzed further measurement of atomic weights, a great benefit to chemistry.
The discrepancy in the atomic weights was later understood to be the result of multiple isotopes of the same element. Although all elements are the product of nuclear fusion of hydrogen into higher elements, it is now understood that atoms consist of both protons (hydrogen nuclei) and neutrons. Neutrons in nuclei decay into protons by emission of beta radiation.
The modern version of Prout's rule is that the atomic mass of a nucleus of proton number P and neutron number N is equal to sum of the masses of its constituent protons and neutrons minus its binding energy.
See also
References
- ^ William Prout (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. Online reprint
- ^ William Prout (1816). Correction of a mistake in the essay on the relation between the specific gravities of bodies in their gaseous state and the weights of their atoms. Annals of Philosophy, 7: 111–13. Online reprint
Further reading
- Gladstone, Samuel (1947). "William Prout (1785-1850)". Journal of Chemical Education 24: 478 – 481.
- Benfey, O. Theodore (1952). "Prout's Hypothesis". Journal of Chemical Education 29: 78 – 81.
- Siegfried, Robert (1956). "The Chemical Basis for Prout's Hypothesis". Journal of Chemical Education 33: 263 – 266.
External links
Wikipedia content modification information:
- This page was last modified on 5 November 2008, at 06:56.
Wikipedia Authorship and Review
Wikipedia content provided here is not reviewed directly by MedLibrary.org. Wikipedia content is authored by an open community of volunteers and is not produced by or in any way affiliated with MedLibrary.org.
Wikipedia Usage Guidelines
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article on "Prout's hypothesis".
The URL for this specific entry is:
All Wikipedia text is available under the terms of the GNU Free Documentation License. (See Copyrights for details). Wikipedia® is a registered trademark of the Wikimedia Foundation, Inc.