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  2. Periodic table - Wikipedia

    en.wikipedia.org/wiki/Periodic_table

    The periodic table, also known as the periodic table of the elements, is an ordered arrangement of the chemical elements into rows (" periods ") and columns (" groups "). It is an icon of chemistry and is widely used in physics and other sciences. It is a depiction of the periodic law, which states that when the elements are arranged in order ...

  3. Composition of the human body - Wikipedia

    en.wikipedia.org/wiki/Composition_of_the_human_body

    About 99% of the mass of the human body is made up of six elements: oxygen, carbon, hydrogen, nitrogen, calcium, and phosphorus. Only about 0.85% is composed of another five elements: potassium, sulfur, sodium, chlorine, and magnesium. All 11 are necessary for life. The remaining elements are trace elements, of which more than a dozen are ...

  4. Carbon group - Wikipedia

    en.wikipedia.org/wiki/Carbon_group

    The carbon group is a periodic table group consisting of carbon (C), silicon (Si), germanium (Ge), tin (Sn), lead (Pb), and flerovium (Fl). It lies within the p-block. In modern IUPAC notation, it is called group 14. In the field of semiconductor physics, it is still universally called group IV.

  5. Types of periodic tables - Wikipedia

    en.wikipedia.org/wiki/Types_of_periodic_tables

    Theodor Benfey's arrangement is an example of a continuous (spiral) table. First published in 1964, it explicitly showed the location of lanthanides and actinides.The elements form a two-dimensional spiral, starting from hydrogen, and folding their way around two peninsulas, the transition metals, and lanthanides and actinides.

  6. 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 9 October 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 extended ...

  7. Group (periodic table) - Wikipedia

    en.wikipedia.org/wiki/Group_(periodic_table)

    Group (periodic table) In the periodic table of the elements, each column is a group. In chemistry, a group (also known as a family) [ 1 ] is a column of elements in the periodic table of the chemical elements. There are 18 numbered groups in the periodic table; the 14 f-block columns, between groups 2 and 3, are not numbered.

  8. Extended periodic table - Wikipedia

    en.wikipedia.org/wiki/Extended_periodic_table

    They considered elements 158 through 164 to be homologues of groups 4 through 10, and not 6 through 12, noting similarities of electron configurations to the period 5 transition metals (e.g. element 159 7d 4 9s 1 vs Nb 4d 4 5s 1, element 160 7d 5 9s 1 vs Mo 4d 5 5s 1, element 162 7d 7 9s 1 vs Ru 4d 7 5s 1, element 163 7d 8 9s 1 vs Rh 4d 8 5s 1 ...

  9. Atom - Wikipedia

    en.wikipedia.org/wiki/Atom

    Dalton concluded that in these oxides, for every two atoms of iron, there are two or three atoms of oxygen respectively (Fe 2 O 2 and Fe 2 O 3). [ b ] [ 7 ] [ 8 ] As a final example: nitrous oxide is 63.3% nitrogen and 36.7% oxygen, nitric oxide is 44.05% nitrogen and 55.95% oxygen, and nitrogen dioxide is 29.5% nitrogen and 70.5% oxygen.