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Law of Triads - Johann Dobereiner
Developed "triads" of the elements. He discovered that Lithium, Sodium and Potassium were a triad of alkali elements. Seeing that the middle element had properties that were the avereages of the other two elements. -
Law of Octaves - John Newlands
John Newlands classified the known 56 elements into 11 groups based on said element's physical properties. He noted that among those elements there were pairs of elemnts that were very simmilar and had atomic weights differing by s multiple of 8, making it called the law of Octaves. -
Dmirti Mendeleev
Created the widely known and accepted periodic table still used today. Left blanks for where he beleived unidentified elements were. He correctely predicted the positions of gallium, scandium and germanium. He sorted it based on atomic mass but some properties deemed slight variations. -
Table- Lothar Meyer
Meyer orgainzed the known 56 elements into a periodic table. It was based on the various periodic properties such as the molar voulume while it was all being sorted by atomic weight. -
Lord Rauleigh - Noble Gases
In 1894 removed oxygen, nitrogen, water and carbon dioxide from a sample of air and found a gas that was 19x heavier than hydrogen. This new gas was very unreactive and possesd an unknown light emission spectrum. He decided to call this noble gas Argon. -
William Ramsey - Noble Gases
First he suggested that newly found argon had its own colum on the periodic table. In 1895 he found helium as a decay product of uranium and matched it an unknown element in the sun that was discovered back in 1868. Then he finally discovered neon, krypton and xenon, and realised these represented a new group in the Periodic table. -
Henry Mosely - Table
He discovered the Atomic Number for all the elements in the periodic table. He re ordered the table to sort them by atomic number, even though it only switched around a few elements. -
Henry Mosely - Gold and aluminum
He conlcuded by looking at the atomic numbers and atomic masses of elements that there were 3 unkonw elements inbetween gold and aluminum. Thus made him conclude there were only 92 elements up to and including uranium. -
Glenn Seaborg - Actinide Series
He bombared uranium, with protons in a machine called a cyclotron to synthetically create a new element called neptuniun, number 93 on the periodic table. Then he created Plutonium by doing the same to uranium and deuterium. These new elements were placed in the f block of the periodic table, called the actinide series.
