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Hennig Brand discovers first element (Phosphorous)
Although elements such as gold, silver, tin, copper, lead and mercury have been known from the start the first scientific discovery of an element occurred in 1649 when Hennig Brand discovered phosphorous. -
Daltons Law
John Dalton proposed "Dalton's Law" describing the relationship between the components in a mixture of gases -
the law of triads
In 1817 Johann Dobereiner developed groups of 3 elements with similar properties called the law of triads -
Letters symbolizing elements
Jakob Berzelius developed a table of atomic weights & introduced letters to symbolize elements -
First attempts at periodic table
in 1862 french geologist A.E.Beguyer de Chancourtois attempts at making a periodic table by arrange the elements in rows -
John newlands arranged elements occurding to Atomic weight
John Newlands arranged the known elements in order of atomic weights & observed similarities between some elements -
dmitri produces a periodic table
Dmitri Mendeleev produced a table based on atomic weights but arranged periodically with elements with similar properties under each other. His Periodic Table included the 66 known elements organized by atomic weights. -
discovering helium
Joseph Norman Lockyer discovered a new element on August 18, 1868 while looking at the chromosphere of the Sun, and named it helium after the Greek word for the Sun (ílios or helios). helium is then found as a noble gas -
63 elements found by 1869
By 1869, a total of 63 elements had been discovered. As the number of known elements grew, scientists began to recognize patterns in the way chemicals reacted and began to devise ways to classify the elements -
discovery of the noble gases
William Ramsay discovered the Noble Gases. -
lord Rayleighs theory
Lord Rayleigh theorized that the nitrogen extracted from air was mixed with another gas, leading to an experiment that successfully isolated a new element, argon, With this discovery, they realized an entire class of gases was missing from the periodic table. -
discovered the source of the radioactivity
Ernest Rutherford discovered the source of radioactivity as decaying atoms -
discovering argon
During his search for argon, Ramsay also managed to isolate helium for the first time while heating cleveite, a mineral. In 1902, having accepted the evidence for the elements helium and argon, Dmitri Mendeleev included these noble gases as group 0 in his arrangement of the elements, which would later become the periodic table
