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  2. Robert Bunsen - Wikipedia

    en.wikipedia.org/wiki/Robert_Bunsen

    Robert Wilhelm Eberhard Bunsen (German: [ˈʁoːbɛʁt ˈbʊnzn̩]; 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]

  3. Caesium - Wikipedia

    en.wikipedia.org/wiki/Caesium

    Caesium (IUPAC spelling; [9] also spelled cesium in American English) is a chemical element; it has symbol Cs and atomic number 55. It is a soft, silvery-golden alkali metal with a melting point of 28.5 °C (83.3 °F; 301.6 K), which makes it one of only five elemental metals that are liquid at or near room temperature.

  4. Discovery of chemical elements - Wikipedia

    en.wikipedia.org/wiki/Discovery_of_chemical_elements

    Wollaston discovered and isolated it from crude platinum samples from South America. [117] 53 Iodine: 1811 B. Courtois: 1811 B. Courtois Courtois discovered it in the ashes of seaweed. [118] The name iode was given in French by Gay-Lussac and published in 1813. [52] Davy gave it the English name iodine in 1814. [52] 3 Lithium: 1817 A. Arfwedson ...

  5. Timeline of the evolutionary history of life - Wikipedia

    en.wikipedia.org/wiki/Timeline_of_the...

    The earliest evidence for life on Earth includes: 3.8 billion-year-old biogenic hematite in a banded iron formation of the Nuvvuagittuq Greenstone Belt in Canada; [30] graphite in 3.7 billion-year-old metasedimentary rocks in western Greenland; [31] and microbial mat fossils in 3.48 billion-year-old sandstone in Western Australia. [32] [33 ...

  6. History of Earth - Wikipedia

    en.wikipedia.org/wiki/History_of_Earth

    The first eon in Earth's history, the Hadean, begins with the Earth's formation and is followed by the Archean eon at 3.8 Ga. [2]: 145 The oldest rocks found on Earth date to about 4.0 Ga, and the oldest detrital zircon crystals in rocks to about 4.4 Ga, [34] [35] [36] soon after the formation of the Earth's crust and the Earth

  7. Timeline of scientific discoveries - Wikipedia

    en.wikipedia.org/wiki/Timeline_of_scientific...

    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.

  8. History of chemistry - Wikipedia

    en.wikipedia.org/wiki/History_of_chemistry

    Modern archaeologists discovered that bronze-tipped crossbow bolts at the tomb of Qin Shi Huang showed no sign of corrosion after more than 2,000 years, because they had been coated in chromium. [12] [13] Chromium was not used anywhere else until the experiments of French pharmacist and chemist Louis Nicolas Vauquelin (1763–1829) in the late ...

  9. Timeline of natural history - Wikipedia

    en.wikipedia.org/wiki/Timeline_of_natural_history

    Late heavy bombardment of the Moon (and probably of the Earth as well) by bolides and asteroids, produced possibly by the planetary migration of Neptune into the Kuiper belt as a result of orbital resonances between Jupiter and Saturn. [5] "Remains of biotic life" were found in 4.1 billion-year-old rocks in Western Australia.