History of the Periodic Table

Events

First Element Found

1669

In 1669 German merchant and amateur alchemist Hennig Brand attempted to created a Philosopher’s Stone; an object that supposedly could turn metals into pure gold. He heated residues from boiled urine, and a liquid dropped out and burst into flames. This was the first discovery of phosphorus.

First Attempts

Approx. 1817

A German chemist named Johann Dobereiner. Found that certain chemicals were chemically similar and can be grouped into groups of 3. In each group of 3, the atomic weight of one of the element was halfway between the atomic weight of the other 2 elements.

Law of Triads

1829

Based on his findings, Dobereiner proposed the Law of Triads in 1829.

Another Attempt

1862

A French geologist named Alexandre-Émile Beguyer de Chancourtois attempted to arrange the elements but this time in a spiral ordered by increasing atomic weight. He noticed that elements that were similar seemed to appear at regular intervals

First Group

1863

English chemist John Newlands divided the then discovered 56 elements into 11 groups, based on characteristics.

The Start

1869

Russian chemist Dmitri Mendeleev, who was considered the "father" to modern Periodic Table.Mendeleev wrote out the names of the elements, along with their atomic weights and other properties, on cards, which he then laid out in rows and columns

Noble Gases

1894

Sir William Ramsay and Lord Rayleigh discovered the noble gases, which were added to the periodic table as group 0

Moseley

1914

Moseley showed that each atomic nucleus could be assigned a number that was equal to the number of units of positive charge associated with it. Once the periodic table was reorganized according to this atomic number instead of atomic weight, the few discrepancies in Mendeleev's system disappeared.