Lesson on Periodic Table

History of the Development of

Periodic Table of Elements

by Arnold Sargento

​1900

Bequerel discovered that electrons and beta particles as identified by the Curies are the same thing.Read more:

https://www.lenntech.com/periodic/history/history-periodic-table.htm#ixzz74eRP2l8w​

​1789

​French chemist Antoine Lavoisier tried grouping the elements as metals and nonmetals

18​29

​German physicist Johann Wolfang Döbereiner observed similarities in physical and chemical properties of certain elements. He arranged them in groups of three in increasing order of atomic weight and called them triads, observing that some properties of the middle element, such as atomic weight and density, approximated the average value of these properties in the other two in each triad. 

​1860

​British chemist John Newlands was the first to arrange the elements into a periodic table with increasing order of atomic masses. He found that every eight elements had similar properties and called this the law of octaves. He arranged the elements in eight groups but left no gaps for undiscovered elements. 

​1869

​Russian chemist Dmitri Mendeleev created the framework that became the modern periodic table, leaving gaps for elements that were yet to be discovered. While arranging the elements according to their atomic weight

​1870

​German chemist Lothar Meyer produced a version of the periodic table similar to Mendeleev.

​He arrange the elements according inceasing atomic number.