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Antoine Lavoisier
In 1789 Antoine Lavoisier published a table of 33 elements. Lavoisier grouped his table into metals and non-metals. This was the start of classifing elements. -
Jons Jakob Berzelius
Berzelius Developed a table of atomic weights and Introduced letters to symbolize elements. -
Johann Dobereiner
Dobereiner finds there are several groups, each group had 3 elements. Each group has similar physical and chemical properties. he called these groups triads. Dobereiners contribution to the table was grouping elements according to similarities. -
John Newlands
John Newlands created the law of octaves. The law of octaves identifys similaritys between elements. Newlands did not leave room for more elements that had not yet been discovered. He was the first to recognise periodicity of properties. -
Lothar Meyer
Meyer placed the know elements in order of increasing atomic mass. He also put them in groups based on the number of bonds an element can form. -
Dmitri Mendeleev
Mendeleev arranged the elements in hortizontal rows in order of increasing atomic mass. he arranged elements with similar properties into vertical columns. He also perdicted the properties of missing element and left gaps for them. He was the first to publish a peroidic table -
William Ramsay
from 1893 to 1898 William Ramsay discovered 5 gases argon heluim krypton neon and xenon this gases were called noble gases . the discover of these gases led to additional columns in the periodic table. -
Henry Moseley
Moseley proposed atomic numbers. The atomic number is the number of protons in the nucleus of the atom.
