1. Henry Gwyn Jeffreys Moseley
A Presentation By: Seth Zurlo, Emily Spraker, Corey Komorowski

2. Before Moseley Thomson's model (1903) Rutherford's model (1911)
Electrons are negatively charged and have mass
Protons are positively charged and spread throughout the atom
"Plum Pudding Model"
Rutherford's model (1911)
A dense concentration of positive charge in the middle of the atom, the "nucleus"
Electrons orbit the nucleus in an unspecified manner
Mendeleev's Periodic table ( )
Ordered by atomic mass/weight
Had periods of 8 or more

3. What's the problem? Thomson’s model was disproven by Rutherford
Rutherford’s model did not specify what differentiated elements
The periodic table relied on the weights of the elements

4. Enter Henry Moseley Moseley worked in a research group with Rutherford
Moseley wanted to find a unique property that differentiate elements besides weight
Moseley wanted to connect the atomic number to a value inside of the atom
Moseley had heard of Antonius van den Broek’s hypothesis, each element’s atomic number indicates the number of protons in a nucleus

5. Moseley’s Experiment Moseley’s experiment consisted of-
Shooting a ray of high-energy electrons at a solid element
After the rays hit the solid element, x-rays would be emitted
These rays’ wavelengths and frequencies would then be measured

6. How’d he do it? Moseley created a machine to shoot the ray
Once the beam was shot it hit the solid element
After the ray impacts the element, x-rays are emitted
The machine then measures the frequency and wavelength of the x-rays

7. What came of it? Moseley’s experiments showed-
The relationship between the atomic number and the number of protons in the nucleus could be expressed as √y = a(z-b)
Y is the frequency, z is the atomic number and a and b are constants
Every element has a specific number of protons in the nucleus
The rearrangement of the periodic table according to the number of protons

8. Development Of A New Atomic Model
Moseley was able to determine the number of positive charges in the nucleus of an atom by using x-ray tubes to measure the wavelengths given off by certain elements he experimented with.
This was the first notion of the atomic number.
He concluded that the atomic number of an element was equal to the number of of protons present in the nucleus of the atom.

9. More Information On Moseley
He was British, born in Weymouth, England
His full name is Henry Gwyn Jeffreys Moseley
Won multiple physics and chemistry prizes at age 18
He had willingly enlisted as a volunteer in the British Army’s Royal Engineers
The second lieutenant died in battle in Gallipoli, Turkey at the young age of 27

10. Works Cited
Moselely and Atomic Number <
Leading up to Moseley: X-Ray Spectra <
Henry Moseley <
Atomic Structure Timeline <
The Atomic Number <
Timeline of Atomic Theroy <