chemistry Chemistry is the scientific study of the properties and behavior of matter. It is a natural science that covers the elements that make up matter to the compounds made of atoms, molecules and ions: their composition, structure, proper ...

, a single bond is a chemical bond between two

atom Every atom is composed of a nucleus and one or more electrons bound to the nucleus. The nucleus is made of one or more protons and a number of neutrons. Only the most common variety of hydrogen has no neutrons. Every solid, liquid, gas, a ...

s involving two valence electrons. That is, the atoms share one pair of

electron The electron ( or ) is a subatomic particle with a negative one elementary electric charge. Electrons belong to the first generation of the lepton particle family, and are generally thought to be elementary particles because they have n ...

s where the bond forms. Therefore, a single bond is a type of

covalent bond A covalent bond is a chemical bond that involves the sharing of electrons to form electron pairs between atoms. These electron pairs are known as shared pairs or bonding pairs. The stable balance of attractive and repulsive forces between ato ...

. When shared, each of the two electrons involved is no longer in the sole possession of the orbital in which it originated. Rather, both of the two electrons spend time in either of the orbitals which overlap in the bonding process. As a

Lewis structure Lewis structures, also known as Lewis dot formulas, Lewis dot structures, electron dot structures, or Lewis electron dot structures (LEDS), are diagrams that show the bonding between atoms of a molecule, as well as the lone pairs of electrons ...

, a single bond is denoted as AːA or A-A, for which A represents an element. In the first rendition, each dot represents a shared electron, and in the second rendition, the bar represents both of the electrons shared in the single bond. A covalent bond can also be a double bond or a

triple bond A triple bond in chemistry is a chemical bond between two atoms involving six bonding electrons instead of the usual two in a covalent single bond. Triple bonds are stronger than the equivalent single bonds or double bonds, with a bond order o ...

. A single bond is weaker than either a double bond or a triple bond. This difference in strength can be explained by examining the component bonds of which each of these types of covalent bonds consists (Moore, Stanitski, and Jurs 393). Usually, a single bond is a sigma bond. An exception is the bond in diboron, which is a pi bond. In contrast, the double bond consists of one sigma bond and one pi bond, and a triple bond consists of one sigma bond and two pi bonds (Moore, Stanitski, and Jurs 396). The number of component bonds is what determines the strength disparity. It stands to reason that the single bond is the weakest of the three because it consists of only a sigma bond, and the double bond or triple bond consist not only of this type of component bond but also at least one additional bond. The single bond has the capacity for rotation, a property not possessed by the double bond or the triple bond. The structure of pi bonds does not allow for rotation (at least not at 298 K), so the double bond and the triple bond which contain pi bonds are held due to this property. The sigma bond is not so restrictive, and the single bond is able to rotate using the sigma bond as the axis of rotation (Moore, Stanitski, and Jurs 396-397). Another property comparison can be made in bond length. Single bonds are the longest of the three types of covalent bonds as interatomic attraction is greater in the two other types, double and triple. The increase in component bonds is the reason for this attraction increase as more electrons are shared between the bonded atoms (Moore, Stanitski, and Jurs 343). Single bonds are often seen in diatomic molecules. Examples of this use of single bonds include H₂, F₂, and

HCl HCL may refer to: Science and medicine * Hairy cell leukemia, an uncommon and slowly progressing B cell leukemia * Harvard Cyclotron Laboratory, from 1961 to 2002, a proton accelerator used for research and development * Hollow-cathode lamp, a s ...

. Single bonds are also seen in molecules made up of more than two atoms. Examples of this use of single bonds include: *Both bonds in H₂O *All 4 bonds in CH₄ Single bonding even appears in molecules as complex as

hydrocarbon In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. Hydrocarbons are examples of group 14 hydrides. Hydrocarbons are generally colourless and hydrophobic, and their odors are usually weak or ...

s larger than methane. The type of covalent bonding in hydrocarbons is extremely important in the

nomenclature Nomenclature (, ) is a system of names or terms, or the rules for forming these terms in a particular field of arts or sciences. The principles of naming vary from the relatively informal conventions of everyday speech to the internationally ag ...

of these molecules. Hydrocarbons containing only single bonds are referred to as

alkane In organic chemistry, an alkane, or paraffin (a historical trivial name that also has other meanings), is an acyclic saturated hydrocarbon. In other words, an alkane consists of hydrogen and carbon atoms arranged in a tree structure in wh ...

s (Moore, Stanitski, and Jurs 334). The names of specific molecules which belong to this group end with the suffix

-ane The suffix -ane in organic chemistry forms the names of organic compounds where the -C-C- group has been attributed the highest priority according to the rules of organic nomenclature. Such organic compounds are called alkanes. They are saturate ...

. Examples include ethane, 2-methylbutane, and

cyclopentane Cyclopentane (also called C pentane) is a highly flammable alicyclic hydrocarbon with chemical formula C5H10 and CAS number 287-92-3, consisting of a ring of five carbon atoms each bonded with two hydrogen atoms above and below the plane. It occ ...

(Moore, Stanitski, and Jurs 335).

References

{{Chemical bonds Chemical bonding

See also

References