Periodic Table Development

Aristotle - Four elements theory

330

Four element theory: earth, air, fire & water. Aristotle could only see Water, Earth, Fire, and Air.

Antoine Lavoisier

Jan 23, 1789

Wrote the first extensive list of elements containing 33 elements.
Distinguished between metals and non-metals.

Dobereiner

Dec 13, 1829

Developed 'triads', groups of 3 elements with similar properties.
Lithium, sodium & potassium formed a triad.
Calcium, strontium & barium formed a triad.
Chlorine, bromine & iodine formed a triad.

John Newlands - Law of Octaves

May 13, 1864

The known elements (>60) were arranged in order of atomic weights and observed similarities between the first and ninth elements, the second and tenth elements etc. He proposed the 'Law of Octaves'.

Lothar Meyer

Jan 13, 1869

Compiled a Periodic Table of 56 elements based on the periodicity of properties such as molar volume when arranged in order of atomic weight.

Demitri Mendeleev

Feb 13, 1869

Produced a table based on atomic weights but arranged 'periodically' with elements with similar properties under each other. Gaps were left for elements that were unknown at that time and their properties predicted

Henry Moseley

Jan 13, 1913

Determined the atomic number of each of the elements.
He modified the 'Periodic Law' to read that the properties of the elements vary periodically with their atomic numbers.