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  2. Periodic table - Wikipedia

    en.wikipedia.org/wiki/Periodic_table

    The chemical elements are what the periodic table classifies and organizes. Hydrogen is the element with atomic number 1; helium, atomic number 2; lithium, atomic number 3; and so on. Each of these names can be further abbreviated by a one- or two-letter chemical symbol; those for hydrogen, helium, and lithium are respectively H, He, and Li. [6]

  3. Nucleosynthesis - Wikipedia

    en.wikipedia.org/wiki/Nucleosynthesis

    After about 20 minutes, the universe had expanded and cooled to a point at which these high-energy collisions among nucleons ended, so only the fastest and simplest reactions occurred, leaving our universe containing hydrogen and helium. The rest is traces of other elements such as lithium and the hydrogen isotope deuterium. Nucleosynthesis in ...

  4. Helium - Wikipedia

    en.wikipedia.org/wiki/Helium

    Hydrogen: Helium: Lithium: Beryllium: Boron: Carbon: Nitrogen: ... On October 20 of the same year, ... Table of thermal and physical properties of helium gas at ...

  5. Big Bang nucleosynthesis - Wikipedia

    en.wikipedia.org/wiki/Big_Bang_nucleosynthesis

    Without major changes to the Big Bang theory itself, BBN will result in mass abundances of about 75% of hydrogen-1, about 25% helium-4, about 0.01% of deuterium and helium-3, trace amounts (on the order of 10 −10) of lithium, and negligible heavier elements. That the observed abundances in the universe are generally consistent with these ...

  6. Extended periodic table - Wikipedia

    en.wikipedia.org/wiki/Extended_periodic_table

    This is an accepted version of this page This is the latest accepted revision, reviewed on 12 November 2024. Periodic table of the elements with eight or more periods Extended periodic table Hydrogen Helium Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine Neon Sodium Magnesium Aluminium Silicon Phosphorus Sulfur Chlorine Argon Potassium Calcium Scandium Titanium Vanadium Chromium ...

  7. B2FH paper - Wikipedia

    en.wikipedia.org/wiki/B2FH_paper

    Beginning with a paper in 1946, and expanded upon in 1954, [7] Hoyle proposed that all atomic nuclei heavier than lithium were synthesized in stars. Both theories agreed that some light nuclei (hydrogen, helium and a small amount of lithium) were not produced in stars, which became the now-accepted theory of Big Bang nucleosynthesis of H, He ...

  8. Period 1 element - Wikipedia

    en.wikipedia.org/wiki/Period_1_element

    A period 1 element is one of the chemical elements in the first row (or period) of the periodic table of the chemical elements.The periodic table is laid out in rows to illustrate periodic (recurring) trends in the chemical behaviour of the elements as their atomic number increases: a new row is begun when chemical behaviour begins to repeat, meaning that analog elements fall into the same ...

  9. Hydrogen - Wikipedia

    en.wikipedia.org/wiki/Hydrogen

    Hydrogen is a chemical element; it has symbol H and atomic number 1. It is the lightest element and, at standard conditions, is a gas of diatomic molecules with the formula H 2, sometimes called dihydrogen, [11] but more commonly called hydrogen gas, molecular hydrogen or simply hydrogen.