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  2. Valence (chemistry) - Wikipedia

    en.wikipedia.org/wiki/Valence_(chemistry)

    For example, nitrogen has a maximum valence of 5, in forming ammonia two valencies are left unattached; sulfur has a maximum valence of 6, in forming hydrogen sulphide four valencies are left unattached. [20] [21] The International Union of Pure and Applied Chemistry (IUPAC) has made several attempts to arrive at an unambiguous definition of ...

  3. Octet rule - Wikipedia

    en.wikipedia.org/wiki/Octet_rule

    The bonding in carbon dioxide (CO 2): all atoms are surrounded by 8 electrons, fulfilling the octet rule.. The octet rule is a chemical rule of thumb that reflects the theory that main-group elements tend to bond in such a way that each atom has eight electrons in its valence shell, giving it the same electronic configuration as a noble gas.

  4. Valence - Wikipedia

    en.wikipedia.org/wiki/Valence

    Valence (chemistry), a measure of an element's combining power with other atoms Valence electron, electrons in the outer shell of an atom's energy levels; Valence quarks, those quarks within a hadron that determine the hadron's quantum numbers

  5. Valence electron - Wikipedia

    en.wikipedia.org/wiki/Valence_electron

    In chemistry and physics, valence electrons are electrons in the outermost shell of an atom, and that can participate in the formation of a chemical bond if the outermost shell is not closed. In a single covalent bond , a shared pair forms with both atoms in the bond each contributing one valence electron.

  6. Covalent bond - Wikipedia

    en.wikipedia.org/wiki/Covalent_bond

    In the diagram of methane shown here, the carbon atom has a valence of four and is, therefore, surrounded by eight electrons (the octet rule), four from the carbon itself and four from the hydrogens bonded to it. Each hydrogen has a valence of one and is surrounded by two electrons (a duet rule) – its own one electron plus one from the carbon.

  7. Double bond rule - Wikipedia

    en.wikipedia.org/wiki/Double_bond_rule

    Moreover, the multiple bonds of the elements with n=2 are much stronger than usual, because lone pair repulsion weakens their sigma bonding but not their pi bonding.) [2] An example is the rapid polymerization that occurs upon condensation of disulfur, the heavy analogue of O 2. Numerous exceptions to the rule exist. [3]

  8. Electron counting - Wikipedia

    en.wikipedia.org/wiki/Electron_counting

    In chemistry, electron counting is a formalism for assigning a number of valence electrons to individual atoms in a molecule. It is used for classifying compounds and for explaining or predicting their electronic structure and bonding. [1] Many rules in chemistry rely on electron-counting:

  9. Polyvalency (chemistry) - Wikipedia

    en.wikipedia.org/wiki/Polyvalency_(chemistry)

    In chemistry, polyvalency (or polyvalence, multivalency) is the property of molecules and larger species, such as antibodies, medical drugs, and even nanoparticles surface-functionalized with ligands, like spherical nucleic acids, that exhibit more than one supramolecular interaction.