A coordinate covalent bond (also known as dative covalent bond) is a special type of covalent bond in which the shared electrons come from one of the atoms only. Once the bond has been formed, its strength is no different than that of a covalent bond.
Coordinate covalent bonds are formed when a Lewis base (an electron donor or giver) donates a pair of electrons to a Lewis Acid (an electron accepter) and the resultant compound is then called an adduct.
Coordinate bonds can be found in many different substances, such as in simple molecules like Carbon Monoxide (CO), which contains one coordinate bond and two normal covalent bonds between the CarbonAtom and the OxygenAtom, or the Ammonium ion (NH4+), where a coordinate bond is formed between a proton (a H+ ion) and the NitrogenAtom. Coordinate bonds are also formed in electron deficient compounds, such as in solid Beryllium Chloride (BeCl2), in which every Beryllium atom is bonded to four chlorine atoms, two with normal covalent bonding, and the other two with coordinate bonds, which will give it a stable octet of electrons.
Coordinate bonding can also be found in coordination complexes involving metal ions, especially if they are transition metal ions. In such complexes, substances in a solution act as Lewis bases and donate their free pairs of electrons to the metal ion, which acts as a Lewis acid and accepts the electrons. Coordinate bonds form and the resulting compound is called a coordination complex, while the electron donors are called ligands. There are many chemicals with atoms that have lone pairs of electrons, often Oxygen, Sulfur, Nitrogen and Halogens or Halide ions, which, in solution, can donate their electron pairs to become ligands. A common ligand is water (H2O), which will form coordination complexes with any hydrated metal ions, like Cu2+, which will form [Cu(H2O)6]2+ in aqueous solution. Other common simple ligands are ammonia (NH3), fluoride ions (F-), chloride ions (Cl-) and cyanide ions (CN-).
Covalentlybonded hydrogen and carbon in a molecule of methane.
Covalentbonding is an intramolecular form of chemical bonding characterized by the sharing of one or more pairs of electrons between two elements, producing a mutual attraction that holds the resultant molecule together.
Pure covalentbonds (which has low melting points, are usually non-soluble, non-conductive, and tend to exist as individual molecules), and ionic bonds (which conversely have high melting points, are soluble, conductive, and generally tend to exist in a crystaline form) are on two opposite ends of the figurative spectrum, and have totally different properties.
Covalentbonding is a form of chemical bonding characterized by the sharing of one or more pairs of electrons, by two atoms, in order to produce a mutual attraction; atoms tend to share electrons, so as to fill their outer electron shells.
Covalentbonds are more common between non-metals, whereas ionic bonding is more common between two metalatoms or a metal and a non-metal atom.
Unlike ionic bonds, where ions are held together by a non-directional coulombic attraction, covalentbonds are highly directional.
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