Name |
Description |
Hennig
Brand
(c.1630-1692) |
1st
discovery of an element (phosphorus) by distilling urine in 1669
Brand was an alchemist in search of the philosopher’s stone,
which reportedly could turn base metals into gold.
|
Johann
Dobereiner
(1780-1849) |
In
1829 he developed the Law of Triads where he stated that in a
group of three elements with similar properties, the weight of
the middle element was the average of the mass of the lightest
and heaviest elements.
Ca, Sr & Ba
(40, 88, 137) = (40 + 137) ÷ 2 = 88
Li, Na & K
(7, 23, 39) = (7 +39) ÷ 2 = 23
Cl, Br & I
(35, 80, 127) = (35 + 127) ÷ 2 = 81
|
Alexander
E. Beguyer de Chancourtois
(1820-1886) |
In 1862 he published the first periodic table which was a list
of all known elements wrapped around a cylinder so that elements
with similar properties lined up in a vertical column.
|
John
Newlands
(1837-1898) |
After arranging 56 known elements by increasing atomic mass he noted that the physical & chemical properties of the elements began to repeat every eight elements.
He was the first to formulate the concept of periodicity in the chemical
elements.
He compared the chemical periodicity to the notes on a musical scale and called his theory the Law of Octaves.
|
Dimitri
Mendeleev
(1834-1907) |
He arranged the elements by increasing atomic weight, grouping
elements with similar properties. Mendeleev changed atomic weights
for some elements.
Published his first periodic table in 1869 which had 17
columns & 4 periods.
Mendeleev’s periodic table left spaces for yet undiscovered
elements. He predicted the properties of 10 elements, 7 were actually
discovered.
Known as the Father of the Periodic Table.
|
Lothar
Meyer
(1830-1895) |
He produced similar results to Mendeleev, while working separately,
but he published his table after Mendeleev.
|
Henry
Moseley
(1887-1915) |
Student of Ernest Rutherford (discoverer of the proton).
Moseley arranged the elements of the periodic table by increasing
atomic number (instead of increasing atomic weight).
After being
killed at age 28 during World War I, Britain adopted the policy
of exempting scientists from fighting in wars.
|
Glenn
T. Seaborg
(1912-1999) |
Involved in the discovery (creation) of elements 94-102 and 106.
He reconfigured the periodic table by placing the lanthanides
& actinides at the bottom of the table.
|
