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Robert Wilhelm Eberhard Bunsen (German:; 30 March 1811 [a] – 16 August 1899) was a German chemist.He investigated emission spectra of heated elements, and discovered caesium (in 1860) and rubidium (in 1861) with the physicist Gustav Kirchhoff. [11]
De Boisbaudran found a new earth in erbia. [147] 18 Argon: 1894 Lord Rayleigh and W. Ramsay: 1894 Lord Rayleigh and W. Ramsay They discovered the gas by comparing the molecular weights of nitrogen prepared by liquefaction from air and nitrogen prepared by chemical means. It is the first noble gas to be isolated.
It is the least electronegative element with stable isotopes, of which it has only one, caesium-133. Caesium is mined mostly from pollucite, while the radioisotopes, especially caesium-137, are extracted from waste produced by nuclear reactors. German chemists Robert Bunsen and Gustav Kirchhoff discovered caesium in 1860 by flame spectroscopy.
5th century BC: The earliest documented mention of a spherical Earth comes from the Greeks in the 5th century BC. [31] It is known that the Indians modeled the Earth as spherical by 300 BC [32] 460 BC: Empedocles describes thermal expansion. [33] Late 5th century BC: Antiphon discovers the method of exhaustion, foreshadowing the concept of a limit.
To give provisional names to his predicted elements, Dmitri Mendeleev used the prefixes eka- / ˈ iː k ə-/, [note 1] dvi- or dwi-, and tri-, from the Sanskrit names of digits 1, 2, and 3, [3] depending upon whether the predicted element was one, two, or three places down from the known element of the same group in his table.
2023 – Physicists from US and China discovered a new state of matter called the chiral bose-liquid state [29] 2024 – Harvard researchers working with Quantinuum announced a new phase of matter non-Abelian topological order [30]
The cave was excavated in the 1930s, with bones and stone artifacts found, before World War Two interrupted the work. Technology at the time could not identify the bones.
As a result, element 173 is expected to behave chemically like an alkali metal, and one that might be far more reactive than even caesium (francium and element 119 being less reactive than caesium due to relativistic effects): [90] [19] the calculated ionisation energy for element 173 is 3.070 eV, [91] compared to the experimentally known 3.894 ...