The Development of the Periodic Table
Date
Scientist
1787
The Development of the Periodic Table
Observation/discovery
Date
Classified known elements into
metals and non-metals, based on
their physical and chemical
properties
1787
Dalton
Scientist
Classified known elements into
metals and non-metals, based on
their physical and chemical
properties
Dalton
Triads – similarities exist in sets of
three elements
Triads – similarities exist in sets of
three elements
Newlands
1869
Newlands
1869
Mosely
Observation/discovery
Mosely
ANSWER
The Development of the Periodic Table
Date
Scientist
Observation/discovery
1787
Lavoisier
Classified known elements into
metals and non-metals, based on
their physical and chemical
properties
1808
Dalton
Elements are made up of small
particles called atoms
1829
Dobereimer
Triads – similarities exist in sets of
three elements
1863
Newlands
Law of Octaves – if elements were
placed in order of increasing
atomic mass, there was a
repetition or periodicity in every
eights element
1869
Mendeleev
Elements arranged in increasing
atomic mass demonstrated similar
physical and chemical properties
occurring at regular intervals
1914
Mosely
Elements arranged in order of
increasing atomic number, similar
chemical properties occur
periodically