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  2. Calcium - Wikipedia

    en.wikipedia.org/wiki/Calcium

    Calcium is a chemical element; it has symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar to its heavier homologues strontium and barium. It is the fifth most abundant element in Earth's crust, and ...

  3. Ion - Wikipedia

    en.wikipedia.org/wiki/Ion

    An ion (/ ˈaɪ.ɒn, - ən /) [1] is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by convention. The net charge of an ion is not zero because its total number of electrons ...

  4. Proton-coupled electron transfer - Wikipedia

    en.wikipedia.org/wiki/Proton-coupled_electron...

    Proton-coupled electron transfer. A Proton-coupled electron transfer (PCET) is a chemical reaction that involves the transfer of electrons and protons from one atom to another. The term was originally coined for single proton, single electron processes that are concerted, [1] but the definition has relaxed to include many related processes.

  5. Isotopes of calcium - Wikipedia

    en.wikipedia.org/wiki/Isotopes_of_calcium

    Calcium (20 Ca) has 26 known isotopes, ranging from 35 Ca to 60 Ca. There are five stable isotopes (40 Ca, 42 Ca, 43 Ca, 44 Ca and 46 Ca), plus one isotope (48 Ca) with such a long half-life that it is for all practical purposes stable. The most abundant isotope, 40 Ca, as well as the rare 46 Ca, are theoretically unstable on energetic grounds ...

  6. Electron configuration - Wikipedia

    en.wikipedia.org/wiki/Electron_configuration

    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 ] For example, the electron configuration of the neon atom is 1s2 2s2 2p6, meaning that the 1s, 2s, and 2p subshells are occupied by two, two, and six ...

  7. Electron - Wikipedia

    en.wikipedia.org/wiki/Electron

    e−. , or. β−. in nuclear reactions) is a subatomic particle with a negative one elementary electric charge. [13] Electrons belong to the first generation of the lepton particle family, [14] and are generally thought to be elementary particles because they have no known components or substructure. [1]

  8. Atom - Wikipedia

    en.wikipedia.org/wiki/Atom

    Electrons and a compact nucleus of protons and neutrons. Atoms are the basic particles of the chemical elements. An atom consists of a nucleus of protons and generally neutrons, surrounded by an electromagnetically bound swarm of electrons. The chemical elements are distinguished from each other by the number of protons that are in their atoms.

  9. Proton - Wikipedia

    en.wikipedia.org/wiki/Proton

    A proton is a stable subatomic particle, symbol. p. , H +, or 1 H + with a positive electric charge of +1 e (elementary charge). Its mass is slightly less than the mass of a neutron and approximately 1836 times the mass of an electron (the proton-to-electron mass ratio). Protons and neutrons, each with a mass of approximately one atomic mass ...