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Hennig Brand - The First Discovery
Even though elements such as gold, silver, tin, copper, lead and mercury where already know, the first scientific discovery of an element was made by a German physician Hennig Brand in 1669 when he discovered the element Phosphorous. He discovered it when he thought urine was the key to turn metals into gold. He was boiling urine when it suddenly burst into flames and then when it cooled down and went hard it gave off a greenish glow. -
Johann Döbereiner - Law of Traids
1817-1829
In 1817 Johann Dobereiner developed Triads which were groups of three elements that had similar properties. He noticed that strontium’s atomic weight fell in between the weight of calcium and barium. He discovered in 1829 that the halogen Triad consisted of chlorine, iodine, bromine and the alkali metal Triad consisted of sodium, lithium and potassium. From these discoveries he proposed that if they were arranged by atomic weight the middle element in properties was the average of the -
A.E.Beguyer de Chancourtois - First Attempt of Periodic Table
In 1862 a French geologist A.E.Beguyer de Chancourtois attempted to create the first periodic table where he positioned the elements on a cylinder in terms of increasing atomic weight. He drew it in a continuous spiral around the cylinder which divided into 16 parts and the elements that were closely related would line up vertically. He proposed that “the properties of the elements are the properties of numbers”. This model of the periodic table was known as the ‘telluric screw’. -
John Newlands - Law of Octaves
1863-1864
In 1863 in a paper written by English chemist John Newlands it was stated that 56 discovered elements were categorised into 11 groups based on their similar physical properties. This meant that many pairs of similar elements existed and some even multiple of eight in atomic weight. He then published his version on the periodic table in 1864 and proposed the Law of Octaves which meant that any element would exhibit analogous behaviour to the eight elements following it in the table. -
Lothar Meyer - Father of the Periodic Table
In 1869 Lothar Meyer constructed a periodic table of 56 elements based on the properties such as molar volume (amount of space occupied by a solid, liquid or gas). Once again the table was arranged in terms of increasing atomic weight. -
Dmitri Mendeleev - Father of the Periodic Table
In 1869 Russian chemist Dmitri Mendeleev placed elements out of order based on their atomic weight at the time but placed periodically. Elements that were similar in properties were placed under each other and gaps were left for future discoveries. He predicted the existence of elements such as aluminium, boron and silicon. Some elements were found later that fit his predictions such as gallium, scandium and germanium. -
Lord Rayleigh - Noble Gases
In 1895 Lord Rayleigh discovered argon a gaseous element that was chemically inert and it didn’t fit any of the known periodic groups. -
William Ramsey - Noble Gases
In 1898 William Ramsey suggested that argon be placed in a family with helium between chlorine and potassium even though its atomic weight was greater than potassium’s. The group was then known as the zero group due to the zero valency of the elements. He predicted the future discovery and properties of neon. -
Ernest Rutherford/Van den Broek - Atomic Structure and the Periodic Table
In 1911 Ernest Rutherford demonstrated that a nuclear charge on a nucleus was proportional to the atomic weight of the element. In 1911 Van den Broek wrote two papers explaining that the atomic weight of an element was equal to the charge on an atom and this charge later termed the atomic number could be used to number the elements on the periodic table. -
Henry Moseley - Atomic number
In 1913 Henry Moseley determined the atomic number of all the known elements and this made him realise that if the elements were placed in order of atomic number instead of atomic weight they would better fit in the periodic table. -
Glenn Seaborg - Modern Periodic Table
Glenn Seaborg discovered plutonium in 1940 and he discovered all the transuranic elements from 94 to 102. He placed the actinide series below the lanthanide series.
