HISTORY OF THE PERIODIC TABLE

LAVOSIER

Discovered 33 elements and differentiated it into 4 groups.

5 gases_ oxygen,hydrogen,nitrogen,light,heat.

17 elements_ Antimony,silver,arscenic,bismuth,cobalt,copper,tin,iron,manganeese,mercury,molybdenium,nickel,gold,platinum,lead,zinc,tungsten.

Nonmetals_ sulphur,phosphorus,coal,chlorine,fluorine,boron.

5 metal oxides_ magnesium,alumina,silica,lime,beritta

JOHN DALTON Relative atomic mass of elements

discovered.

DOBEREINER(1829)

Law of Triads Dobereiner arranged the elements of

similar properties in group of three called triads.

Döbereiner triads.mp4

JOHN NEWLANDS (1865)

Law of Octaves Newlands arranged the elements in

the order of increasing atomic weights. He noticed that every succeeding eighth element repeated the properties of the first like the eighth note on an octave in music.

John Alexander Reina Newlands.mp4

DMITRI MENDELEEV

Periodic law published. Periodic table proposed based on the

periodicity of elements. Here elements are arranged on the basis of

atomic mass.

HENTRY MOSTLY

Mostly reforms Mendeleev’s periodic table on the basis of atomic number.