Download File

Unit 7: Periodic
Table
Chapters 6 & 7
Chemistry 1K
Cypress Creek High
School
Part 1:
History of
the Periodic
Table
Johann Wolfgang Döbereiner
German chemist 1780-1849
Noticed that there was a pattern
in the atomic masses and
atomic numbers of certain
elements
These sets of patterns became
known as “Döbereiner's triads”
Johann Wolfgang Döbereiner
John Newlands
English chemist 1837-1898
In 1865, proposed the Law
of Octaves whereby every
eighth element has similar
properties.
John Newlands
Dmitri Mendeleev
Russian chemist 1834-1907
Arranged periodic table by
increasing atomic mass
Aligned properties in
vertical columns
Some elements fell into the
wrong column lik Te & I ; Co
& Ni
Dmitri Mendeleev
Henry Moseley
English physicist 1887-1915
Rearranged the modern table
by atomic number
Used X-ray spectrometer to
find the atomic numbers
Henry Moseley