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In chemistry, the valence (US spelling) or valency (British spelling) of an atom is a measure of its combining capacity with other atoms when it forms chemical compounds or molecules. Valence is generally understood to be the number of chemical bonds that each atom of a given chemical element typically forms.
Monovalence or Monovalent may refer to: Monovalent ion, an atom, ion, or chemical group with a valency of one, which thus can form one covalent bond; Monovalent vaccine, a vaccine directed at only one pathogen; Monovalent antibody, an antibody with affinity for one epitope, antigen, or strain of microorganism
Aluminium does not experience the inert-pair effect, a phenomenon where valence s electrons are poorly shielded from nuclear charge due to the presence of filled d and f orbitals. [1] As such, aluminium (III) ( Al 3 + {\displaystyle {\ce {Al^3+}}} ) is the much more common oxidation state for aluminium.
For example, the electronic configuration of phosphorus (P) is 1s 2 2s 2 2p 6 3s 2 3p 3 so that there are 5 valence electrons (3s 2 3p 3), corresponding to a maximum valence for P of 5 as in the molecule PF 5; this configuration is normally abbreviated to [Ne] 3s 2 3p 3, where [Ne] signifies the core electrons whose configuration is identical ...
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.
It is a very stable group in most molecules. While the methyl group is usually part of a larger molecule, bonded to the rest of the molecule by a single covalent bond (−CH 3), it can be found on its own in any of three forms: methanide anion (CH − 3), methylium cation (CH + 3) or methyl radical (CH • 3).
For other polyatomic molecules, an MO diagram may show one or more bonds of interest in the molecules, leaving others out for simplicity. Often even for simple molecules, AO and MO levels of inner orbitals and their electrons may be omitted from a diagram for simplicity. In MO theory molecular orbitals form by the overlap of atomic orbitals.
Valence bond treatments are restricted to relatively small molecules, largely due to the lack of orthogonality between valence bond orbitals and between valence bond structures, while molecular orbitals are orthogonal. Additionally, valence bond theory cannot explain electronic transitions and spectroscopic properties as effectively as MO theory.