Covalently bonded hydrogen and carbon in a molecule of methane. One way of representing covalent bonding in a molecule is with a dot and cross diagram.

Covalent bonding is an intramolecular form of chemical bonding characterized by the sharing of one or more pairs of electrons between two species, producing a mutual attraction that holds the resultant molecule together. Atoms tend to share electrons in such a way that their outer electron shells are filled. Such bonds are always stronger than the intermolecular hydrogen bond and similar in strength to or stronger than the ionic bond. Image File history File links Covalent. ... Image File history File links Covalent. ... R-phrases S-phrases , , , Flash point −188 °C Autoignition temperature 537 °C Explosive limits 5–15% Supplementary data page Structure and properties Thermodynamic data Spectral data UV, IR, NMR, MS Related compounds Related alkanes Ethane Propane Related compounds Methanol Chloromethane Except where noted otherwise, data are given for materials in... A dot and cross diagram of a molecule of water showing the outer shells of each atom. ... A chemical bond is the physical phenomenon of chemical substances being held together by attraction of atoms to each other through sharing, as well as exchanging, of electrons -or electrostatic forces. ... Properties The electron is a fundamental subatomic particle that carries a negative electric charge. ... In general, a molecule is the smallest particle of a pure chemical substance that still retains its composition and chemical properties. ... Properties An atom (Greek άτομον from ά: non and τομον: divisible) is a submicroscopic structure found in all ordinary matter. ... In atomic physics, an electron shell is a group of atomic orbitals with the same value of the principal quantum number n. ... Intermolecular forces are electromagnetic forces which act between molecules or between widely separated regions of a macromolecule. ... Hydrogen bonds between water molecules are diagramatically represented by the black lines. ... Electron configurations of lithium and fluorine. ...

Covalent bonding most frequently occurs between atoms with similar electronegativities. For this reason, non-metals tend to engage in covalent bonding more readily since metals have access to metallic bonding, where the easily-removed electrons are more free to roam about. For non-metals, liberating an electron is more difficult, so sharing is the only option when confronted with another species of similar electronegativity. Electronegativity is a measure of the ability of an atom or molecule to attract electrons in the context of a chemical bond. ... Metallic bonding is intramolecular bonding within metals. ...

However, covalent bonding involving metals is particularly important, especially in industrial catalysis and process chemistry. Many polymerization techniques require catalysis involving metal-organic covalent bonds. In their more useful applications, metals often engage in more exotic covalent bonding, such as those between a metal and the σ bond of molecular hydrogen, or between a metal and the π bond of an alkane or alkene. General Name, Symbol, Number hydrogen, H, 1 Chemical series nonmetals Group, Period, Block 1, 1, s Appearance colorless Atomic mass 1. ... It has been suggested that List of alkanes be merged into this article or section. ... An alkene in organic chemistry is an unsaturated hydrocarbon containing at least one carbon to carbon double bond. ...

History

The idea of covalent bonding can be traced to Gilbert N. Lewis, who in 1916 described the sharing of electron pairs between atoms. He introduced the so called Lewis Notation or Electron Dot Notation in which valence electrons (those in the outer shell) are represented as dots around the atomic symbols. Pairs of electrons located between atoms represent covalent bonds. Multiple pairs represent multiple bonds, such as double and triple bonds. Some examples of Electron Dot Notation are shown in the following figure. An alternative form, in which bond-forming electron pairs are represented as solid lines, is shown alongside. Image File history File links Electron_dot. ... Lewis in the Berkeley Lab Gilbert Newton Lewis (October 23, 1875-March 23, 1946) was a famous American physical chemist. ... 1916 (MCMXVI) is a leap year starting on Saturday (link will take you to calendar) // Events January-February January 1 - The Royal Army Medical Corps first successful blood transfusion using blood that had been stored and cooled. ... It has been suggested that Lewis dot diagram be merged into this article or section. ... Categories: Chemistry stubs | Chemistry ...

While the idea of shared electron pairs provides an effective qualitative picture of covalent bonding, quantum mechanics is needed to understand the nature of these bonds and predict the structures and properties of simple molecules. Heitler and London are credited with the first successful quantum mechanical explanation of a chemical bond, specifically that of molecular hydrogen, in 1927. Their work was based on the valence bond model, which assumes that a chemical bond is formed when there is good overlap between the atomic orbitals of participating atoms. These atomic orbitals are known to have specific angular relationships between each other, and thus the valence bond model can successfully predict the bond angles observed in simple molecules. A simple introduction to this subject is provided in Basics of quantum mechanics. ... Walter Heinrich Heitler (02. ... Fritz Wolfgang London (March 7, 1900–March 30, 1954) was a Jewish German-American physicist for whom the London force is named. ... Molecular hydrogen, H2, is a molecule formed from two atoms of hydrogen. ... 1927 (MCMXXVII) was a common year starting on Saturday (link will take you to calendar). ... An atomic orbital is the description of the behavior of an electron in an atom according to quantum mechanics. ...

Bond Polarity

There are two types of covalent bonds: Polar covalent bonds, and non-polar (or pure) covalent bonds. The most widely-accepted definition of polar covalence is the occurrence of the atoms involved of an electronegativity difference less than 1.67 (though some texts read 1.7), but greater than zero. A pure covalent bond is a bond that occurs when the atoms involved have an electronegativity difference of zero (though some texts read less than 0.2). A commonly-used example of a polar compound is water (H2O). ... Electronegativity is a measure of the ability of an atom or molecule to attract electrons in the context of a chemical bond. ...

Pure covalent bonds (which are usually non-soluble, are electrically non-conductive, and tend to exist as individual molecules), and ionic bonds (which are soluble, are electrically conductive when molten or in solution, and, in general, tend to exist in a crystalline form) are on two opposite ends of the spectrum and have different properties. Polar covalent bonds fall in the middle and have properties of both. It has been suggested that this article or section be merged with Solution. ... En [ [ ciencia ] ] y [ [ ingeniería ] ], los conductores son los materiales de los cuales contenga las cargas movibles [ [ electricidad ] ]. Cuando una diferencia potencial eléctrica se impresiona a través de puntos separados en un conductor, las cargas móviles dentro del conductor se fuerzan para moverse, y una corriente eléctrica entre esos puntos aparece... Electron configurations of lithium and fluorine. ... Crystal (disambiguation) Insulin crystals A crystal is a solid in which the constituent atoms, molecules, or ions are packed in a regularly ordered, repeating pattern extending in all three spatial dimensions. ...

Bond order

Bond order is a term that describes the number of pairs of electrons shared between atoms forming a covalent bond. Bond order is the number of bonds between a pair of atoms. ...

1) The most common type of covalent bond is the single bond, sharing only one pair of electrons between two atoms. It usually consists of one sigma bond. Electron atomic and molecular orbitals, showing among others the sigma bond of two s-orbitals and a sigma bond of two p-orbitals In chemistry, sigma bonds (σ-bonds) are bonds where there is no nodal plane containing the line segment between the two bonded species. ...

All bonds with more than one shared pair are called multiple covalent bonds.

2) Sharing two pairs is called a double bond. An example is in ethylene (between the carbon atoms). It usually consists of one sigma bond and one pi bond. R-phrases R12, R67 S-phrases S2, S9, S16, S33, S46 Flash point Flammable gas Explosive limits 2. ... Electron atomic and molecular orbitals, showing among others the sigma bond of two s-orbitals and a sigma bond of two p-orbitals In chemistry, sigma bonds (σ-bonds) are bonds where there is no nodal plane containing the line segment between the two bonded species. ... Electron atomic and molecular orbitals, showing a Pi-bond at the bottom right of the picture In chemistry, pi bonds (π bonds) are bonds with a single nodal plane containing the line segment between the two atoms. ...

3) Sharing three pairs is called a triple bond. An example is in hydrogen cyanide (between C and N). It usually consists of one sigma bond and two pi bonds. Hydrogen cyanide is a chemical compound with chemical formula HCN. A solution of hydrogen cyanide in water is called hydrocyanic acid or prussic acid. ... Electron atomic and molecular orbitals, showing among others the sigma bond of two s-orbitals and a sigma bond of two p-orbitals In chemistry, sigma bonds (σ-bonds) are bonds where there is no nodal plane containing the line segment between the two bonded species. ... Electron atomic and molecular orbitals, showing a Pi-bond at the bottom right of the picture In chemistry, pi bonds (π bonds) are bonds with a single nodal plane containing the line segment between the two atoms. ...

4) Quadruple bonds, though rare, exist. Both carbon and silicon can theoretically form these; however, the formed molecules are explosively unstable. Stable quadruple bonds are observed as transition metal-metal bonds, usually between two transition metal atoms in organometallic compounds. Molybdenum and Ruthenium are the elements most commonly observed with this bonding configuration. An example of a quadruple bond is also found in Di-tungsten tetra(hpp). General Name, Symbol, Number carbon, C, 6 Chemical series nonmetals Group, Period, Block 14, 2, p Appearance black (graphite) colorless (diamond) Atomic mass 12. ... General Name, Symbol, Number silicon, Si, 14 Chemical series metalloids Group, Period, Block 14, 3, p Appearance dark gray, bluish tinge Atomic mass 28. ... Organometallic have classically been compounds having bonds between one or more metal atoms and one or more carbon atoms of an organyl group. ... General Name, Symbol, Number molybdenum, Mo, 42 Chemical series transition metals Group, Period, Block 6, 5, d Appearance gray metallic Atomic mass 95. ... General Name, Symbol, Number ruthenium, Ru, 44 Chemical series transition metals Group, Period, Block 8, 5, d Appearance silvery white metallic Atomic mass 101. ... the hpp ligand anion Di-tungsten tetra(hpp) or W2(hpp)4 is a di-tungsten paddlewheel compound with four hpp or hexahydropyrimidopyrimidine ligands. ...

5) Quintuple bonds are found to exist in certain chromium dimers. A Quintuple Bond in chemistry is an unusual type of chemical bond first observed in 2005 in a chromium dimer in an organometallic compound. ... General Name, Symbol, Number chromium, Cr, 24 Chemical series transition metals Group, Period, Block 6, 4, d Appearance silvery metallic Atomic mass 51. ...

6) Sextuple bonds, of order 6, have also been observed in transition metals in the gaseous phase at very low temperatures and are extremely rare. In chemistry, the term transition metal (sometimes also called a transition element) has two possible meanings: It commonly refers to any element in the d-block of the periodic table, including zinc and scandium. ...

Other more exotic bonds, such as three center bonds are known and defy the conventions of bond order. It is also important to note that bond order is an integer value only in the elementary sense and is often fractional in more advanced contexts. In chemistry, a three-center bond is a type of covalent bond, in which one pair of electrons joins three atoms rather than the usual two. ...

Coordinate covalent bonds

A special case is called a dative covalent bond, also known as a coordinate covalent bond, which occurs when one atom gives both of the electrons in the bond. 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. ... 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. ...

Resonance

Some structures can have more than one valid Lewis Dot Structure (for example, ozone, O₃). In an LDS diagram of O₃, the center atom will have a single bond with one atom and a double bond with the other. The LDS diagram cannot tell us which atom has the double bond; the first and second adjoining atoms have equal chances of having the double bond. These two possible structures are called resonance structures. In reality, the structure of ozone is a resonance hybrid between its two possible resonance structures. Instead of having one double bond and one single bond, there are actually two 1.5 bonds with approximately three electrons in each at all times. For the Moldavian pop group see O-Zone Ozone (O3) is an allotrope of oxygen, the molecule consisting of three oxygen atoms instead of the more stable diatomic O2. ... Resonance structures are diagrammatic tools in organic chemistry to symbolize resonant bonds between atoms in molecules. ...

A special resonance case is exhibited in aromatic rings of atoms (for example, benzene). Aromatic rings are composed of atoms arranged in a circle (held together by covalent bonds) that alternate between single and double bonds according to their LDS. In actuality, the electrons tend to be disambiguously and evenly spaced within the ring. Electron sharing in aromatic structures is often represented with a ring inside the circle of atoms. In chemistry, an aromatic molecule is one in which electrons are free to cycle around circular arrangements of atoms, which are alternately singly and doubly bonded to one another. ... Benzene, also known as C6H6, PhH, and benzol, is an organic chemical compound that is a colorless and flammable liquid with a pleasant, sweet smell. ...

Current theory

Today the valence bond model has been supplemented with the molecular orbital model. In this model, as atoms are brought together, the atomic orbitals interact to form hybrid molecular orbitals. These molecular orbitals are a cross between the original atomic orbitals and generally extend between the two bonding atoms. Electron atomic and molecular orbitals In quantum chemistry, the molecular electronic states, i. ...

Using quantum mechanics it is possible to calculate the electronic structure, energy levels, bond angles, bond distances, dipole moments, and frequency spectra of simple molecules with a high degree of accuracy. Currently, bond distances and angles can be calculated as accurately as they can be measured (distances to a few pm and bond angles to a few degrees). For small molecules, energy calculations are sufficiently accurate to be useful for determining thermodynamic heats of formation and kinetic activation energy barriers.

See also

• Chemical bond
• Ionic bond
• Linear combination of atomic orbitals
• Metallic bonding

A chemical bond is the physical phenomenon of chemical substances being held together by attraction of atoms to each other through sharing, as well as exchanging, of electrons -or electrostatic forces. ... Electron configurations of lithium and fluorine. ... The linear combination of atomic orbitals molecular orbital method (usually called the LCAO MO method) is a technique for calculating molecular orbitals in quantum chemistry. ... Metallic bonding is intramolecular bonding within metals. ...

External links

• Covalent Bonds and Molecular Structure