A.Y. Chen Illustration & Design
  • Home
  • Portfolio
    • National Science Foundation (NSF)
    • Science magazine art
    • Vector Art
    • Black & White
    • Classic work
  • Animation
  • Blog
  • Contact
  • Children's book art

Arguing over organizational systems

2/4/2016

0 Comments

 
Periodic table history, Antonius van den Broeck, Henry Moseley, discovery of the atomic number
Mendeleev and his predecessors based their chart organization according to atomic weight and chemical properties, which were proven to have a strong correlation. However, as more elements were discovered, these two properties did not always accurately predict where the next element should fall; thus that strong relationship between atomic weight and chemical properties didn't always match.

Antonius van den Broeck was the first to hypothesize that there must be another factor that was more influential on the element’s identity other than atomic weight. He had no data however, to support his hypothesis.

So Henry Moseley devised an experiment based on the result of high-energy, negatively-charged electrons that are shot at elemental substances with each successive chemical element on the table. The X-ray emitted incrementally increased at a consistent rate. So if you look at the graph on the right side, this means that when he shot these electrons at Hydrogen, a certain X-ray emission occurred. Then when he shot it at the next known element, Helium, an equally unique X-ray emission resulted that was at a greater but consistent increase from Hydrogen. When he went on to Lithium, that X-ray emission increased again. When the square root was taken of these individual x-ray emissions, there was a beautiful linear correlation.

This graph is a simplified version explanation, as the emission quantity was NOT one-to-one as I’ve explained it, but the general concept is the same. What he did deduce from this is that another factor within the atom must be giving definition to the element, and as the quantity of that factor changed, so too did the identity of the element. This factor also correlated much more strongly to the organization of chemical property than atomic mass.

What was this factor? Atomic number, or, the number of protons, the positively-charged particle within the atom!

0 Comments



Leave a Reply.


    The purpose of this blog is to explore more effective and exciting ways to communicate science.

    Archives

    June 2017
    May 2017
    April 2017
    March 2017
    February 2017
    January 2017
    December 2016
    November 2016
    October 2016
    September 2016
    August 2016
    July 2016
    June 2016
    May 2016
    April 2016
    March 2016
    February 2016
    January 2016
    December 2015
    November 2015
    October 2015
    September 2015
    August 2015
    July 2015
    June 2015
    May 2015
    April 2015
    March 2015

    RSS Feed

Powered by Create your own unique website with customizable templates.