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  2. Composition of the human body - Wikipedia

    en.wikipedia.org/wiki/Composition_of_the_human_body

    Parts-per-million cube of relative abundance by mass of elements in an average adult human body down to 1 ppm. 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 ...

  3. Molecular model - Wikipedia

    en.wikipedia.org/wiki/Molecular_model

    John Dalton represented compounds as aggregations of circular atoms, and although Johann Josef Loschmidt did not create physical models, his diagrams based on circles are two-dimensional analogues of later models. [2] August Wilhelm von Hofmann is credited with the first physical molecular model around 1860. [3]

  4. Free body diagram - Wikipedia

    en.wikipedia.org/wiki/Free_body_diagram

    A free body diagram is not a scaled drawing, it is a diagram. The symbols used in a free body diagram depends upon how a body is modeled. [6] Free body diagrams consist of: A simplified version of the body (often a dot or a box) Forces shown as straight arrows pointing in the direction they act on the body

  5. Lewis structure - Wikipedia

    en.wikipedia.org/wiki/Lewis_structure

    Another shorthand structural diagram is the skeletal formula (also known as a bond-line formula or carbon skeleton diagram). In a skeletal formula, carbon atoms are not signified by the symbol C but by the vertices of the lines. Hydrogen atoms bonded to carbon are not shown—they can be inferred by counting the number of bonds to a particular ...

  6. Atom - Wikipedia

    en.wikipedia.org/wiki/Atom

    For example, a transfer of a single electron between atoms is a useful approximation for bonds that form between atoms with one-electron more than a filled shell, and others that are one-electron short of a full shell, such as occurs in the compound sodium chloride and other chemical ionic salts. Many elements display multiple valences, or ...

  7. Atomic packing factor - Wikipedia

    en.wikipedia.org/wiki/Atomic_packing_factor

    Indeed, three are the atoms in the middle layer (inside the prism); in addition, for the top and bottom layers (on the bases of the prism), the central atom is shared with the adjacent cell, and each of the six atoms at the vertices is shared with other six adjacent cells. So the total number of atoms in the cell is 3 + (1/2)×2 + (1/6)×6×2 = 6.

  8. Electron configuration - Wikipedia

    en.wikipedia.org/wiki/Electron_configuration

    Electron atomic and molecular orbitals A Bohr diagram of lithium. In atomic physics and quantum chemistry, the electron configuration is the distribution of electrons of an atom or molecule (or other physical structure) in atomic or molecular orbitals. [1]

  9. Nucleosynthesis - Wikipedia

    en.wikipedia.org/wiki/Nucleosynthesis

    Diagram illustration the creation of new elements by the alpha process Nucleosynthesis is the process that creates new atomic nuclei from pre-existing nucleons (protons and neutrons) and nuclei. According to current theories, the first nuclei were formed a few minutes after the Big Bang , through nuclear reactions in a process called Big Bang ...