HISTORY OF THE ATOMIC THEORY: Henry Moseley Kristen DeZeery, Jala Glaze & Whinter Townsel

Moseley’s Experimental Design Moseley’s experimental design was based on the diffraction of x-rays and the nature of the spectra produced by scattered x- rays. Moseley devised a system that allowed him to look at the way x-ray diffraction patterns produced one element after another in an orderly fashion. He discovered that when elements were arranged in ascending order according to their atomic masses,they are also arranged in ascending order according to their nuclear charge. This property is such a defining characteristic of atoms and elements that it was named the atomic number.

the evidence leading to change in previous model of atom -When he beamed the x rays at certain crystalline materials, they are diffracted by atoms within the crystals, forming a continuous spectrum on which is superimposed a series of bright lines. The number and location of theses lines are characteristics of the element or elements being studied. -The variation in atomic masses between adjacent elements is never consistent, whereas the variation in nuclear charge is always precisely one. This property is a clear defining characteristic of atoms and elements that it was given the special name of atomic number.

How Moseley’s work changed the Atomic Model: Moseley’s work changed the atomic model in which we now look at elements by their atomic number rather than their masses. The atomic number is now one of the “single most important” things.

X-Ray frequencies we now use atomic number to organize the elements in order

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