1. Development of the Periodic Table
By Mike Marshall and Collin Malone

2. Recent Developments Most elements only discovered in the 19th century
Scientists were able to isolate different elements
Number of elements more that doubled in 65 years
1800 – 31, 1865 – 63

3. Original two Dmitri Mendeleev and Lothar Meyer
Russia and Germany respectively
Forerunners for development
Unaware of atomic number
Ordered by atomic weight

4. Meyer Produced more extensive table originally 1870
Produced table very similar to Mendeleev
Listed periodic valence charges based on atomic weight

6. Mendeleev Youngest of 17 children
Studied in Germany for two years to further chemistry knowledge
Taught chemistry for some time after graduation
Produced work in 1869
Taught chemistry until 1890

7. Mendeleev
Predicted elements Gallium (eka-aluminum) and Germanium (eka-silicon)
Elements with similar characteristics in same families
Left spaces for elements that were yet to be discovered
Predicted properties and left blank to be filled in upon discovery

8. Mendeleev’s Table

9. Henry Moseley Born 1887 Studied under Rutherford
Made contributions fifty years after Mendeleev’s development
Fought in World War I
Died in 1915 in Gallipoli

10. Moseley English physicist Developed atomic number
Discovered that each element produced unique wavelength of X-ray spectral line
Generally increased as atomic mass increased
Arranged in order by assigning unique whole number based on frequency
Called this whole number the number of protons and electrons in each element
Cleared up discrepancies with Mendeleev’s table (Argon and Potassium)

11. Quiz
____________ and ___________ created similar periodic tables in 1869 and 1870.
____________ arranged the elements on the periodic table in order of atomic number.
What type of electromagnetic radiation was used to find the atomic numbers of elements?
Is the periodic table that we use based on atomic mass or atomic number?
Name one of the two elements that Mendeleev predicted would exist based on his periodic table.

12. Answers Dmitri Mendeleev & Lothar Meyer Henry Moseley X-Rays
Atomic Number
Gallium (eka-aluminum) or Germanium (eka-silicon)

13. Bibliography
"A Brief History of the Development of Periodic Table." Western Oregon University. Western Oregon University, Web. 8 Nov <
Brown, Theodore L., et al. Chemistry: The Central Science. 9th ed Upper Saddle River, NJ: Prentice Hall, Print.
"Dmitri Mendeleev." History of the Periodic Table. N.p., n.d. Web. 8 Nov <
Leach, Mark R. "Periodic Table: Formulations." The Chemogenisis Web Book. N.p., Web. 8 Nov <
"Who was Henry Moseley." Kiwi Web: Chemistry and New Zealand. N.p., Web. 8 Nov <