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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. 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.

  4. 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.

  5. Carbon-based life - Wikipedia

    en.wikipedia.org/wiki/Carbon-based_life

    The most important characteristics of carbon as a basis for the chemistry of cellular life are that each carbon atom is capable of forming up to four valence bonds with other atoms simultaneously, and that the energy required to make or break a bond with a carbon atom is at an appropriate level for building large and complex molecules which may ...

  6. 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

  7. Chemical polarity - Wikipedia

    en.wikipedia.org/wiki/Chemical_polarity

    In chemistry, polarity is a separation of electric charge leading to a molecule or its chemical groups having an electric dipole moment, with a negatively charged end and a positively charged end. Polar molecules must contain one or more polar bonds due to a difference in electronegativity between the bonded atoms.

  8. Charge number - Wikipedia

    en.wikipedia.org/wiki/Charge_number

    Charge number or valence [1] of an ion is the coefficient that, when multiplied by the elementary charge, gives the ion's charge. [2]For example, the charge on a chloride ion, , is , where e is the elementary charge.

  9. Resonance (chemistry) - Wikipedia

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

    Contributing structures of the carbonate ion. In chemistry, resonance, also called mesomerism, is a way of describing bonding in certain molecules or polyatomic ions by the combination of several contributing structures (or forms, [1] also variously known as resonance structures or canonical structures) into a resonance hybrid (or hybrid structure) in valence bond theory.