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  2. Calcium - Wikipedia

    en.wikipedia.org/wiki/Calcium

    Like the other elements placed in group 2 of the periodic table, calcium has two valence electrons in the outermost s-orbital, which are very easily lost in chemical reactions to form a dipositive ion with the stable electron configuration of a noble gas, in this case argon. [10]

  3. Discovery of chemical elements - Wikipedia

    en.wikipedia.org/wiki/Discovery_of_chemical_elements

    Found on Earth in trace quantities by Olavi Erämetsä in 1965; so far, promethium is the most recent element to have been found on Earth. [194] 97 Berkelium: 1949 G. Thompson, A. Ghiorso and G. T. Seaborg (University of California, Berkeley) Created by bombardment of americium with alpha particles. [195] 98 Californium: 1950 S. G. Thompson, K ...

  4. History of the periodic table - Wikipedia

    en.wikipedia.org/wiki/History_of_the_periodic_table

    This is an accepted version of this page This is the latest accepted revision, reviewed on 17 November 2024. Development of the table of chemical elements The American chemist Glenn T. Seaborg —after whom the element seaborgium is named—standing in front of a periodic table, May 19, 1950 Part of a series on the Periodic table Periodic table forms 18-column 32-column Alternative and ...

  5. Alkaline earth metal - Wikipedia

    en.wikipedia.org/wiki/Alkaline_earth_metal

    The alkaline earth metals are six chemical elements in group 2 of the periodic table. They are beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra). [1] The elements have very similar properties: they are all shiny, silvery-white, somewhat reactive metals at standard temperature and pressure. [2]

  6. Timeline of the discovery and classification of minerals

    en.wikipedia.org/wiki/Timeline_of_the_discovery...

    The chemical elements were discovered in identified minerals and with the help of the identified elements the mineral crystal structure could be described. One milestone was the discovery of the geometrical law of crystallization by René Just Haüy , a further development of the work by Nicolas Steno and Jean-Baptiste L. Romé de l'Isle (the ...

  7. Scientists Probed a Medieval Alchemist’s Artifacts—and Found ...

    www.aol.com/scientists-probed-medieval-alchemist...

    The authors examined cross sections of the shards for 31 trace elements using mass spectrometry by converting sample molecules into charged ions.While there was plenty of the expected elements on ...

  8. Döbereiner's triads - Wikipedia

    en.wikipedia.org/wiki/Döbereiner's_triads

    By 1829, Döbereiner had found other groups of three elements (hence "triads") whose physical properties were similarly related. [2] He also noted that some quantifiable properties of elements (e.g. atomic weight and density) in a triad followed a trend whereby the value of the middle element in the triad would be exactly or nearly predicted by taking the arithmetic mean of values for that ...

  9. Periodic table - Wikipedia

    en.wikipedia.org/wiki/Periodic_table

    Elements are placed in the periodic table according to their electron configurations, [38] the periodic recurrences of which explain the trends in properties across the periodic table. [39] An electron can be thought of as inhabiting an atomic orbital, which characterizes the probability it can be found in any particular region around the atom.