Everything about Sigma Bond totally explained
In
chemistry,
sigma bonds (
σ bonds) are a type of
covalent chemical bond. Sigma bonding is most clearly defined for diatomic molecules using the language and tools of
symmetry groups. In this formal approach, a σ-bond is symmetrical with respect to rotation about the bond axis. By this definition, common forms of sigma bonds are s+s, p
z+p
z, and s+p
z, and d
z2+d
z2 (where z is defined as the bond axis). Quantum theory also indicates that molecular orbitals (MO) of identical symmetry mix. As a practical consequence of mixing in diatomic molecules, the
wavefunctions s+s and p
z+p
z molecular orbitals become blended. The extent of mixing (or blending) depends on the relative energies of the like-symmetry MO's.
For homodiatomics, bonding σ orbitals have no nodal planes between the bonded atoms. The corresponding
antibonding, or σ* orbital, is defined by the presence of a nodal plane between these two bonded atoms.
Sigma bonds are the strongest type of
covalent bonds.
Electrons in sigma bonds are sometimes referred to as sigma electrons.
The symbol σ is the Greek letter for s. When viewed down the bond axis, a σ MO resembles an
s atomic orbital.
Sigma bonds in polyatomic compounds
They are obtained by head on overlap of atomic orbitals. The concept of sigma bonding is extended, albeit loosely, to describe bonding interactions involving overlap a single lobe of one
orbital with a single lobe of another. For example,
propane is described as consisting of ten sigma bonds, one each for the two C-C bonds and one each for the eight C-H bonds. The σ bonding in such a polyatomic molecule is highly delocalized, which conflicts with the two-orbital, one-bond concept. Despite this complication, the concept of σ bonding is extremely powerful and hence pervasive.
Sigma bonds in multiply bonded species
Compounds that feature multiple bonds, such as
ethylene and
chromium(II) acetate have sigma bonds between the multiply bonded atoms. These sigma bonds are supplemented by π-bonds, for example in the case of ethylene, and even δ-bonds, for example in the case of chromium(II) acetate.
Further Information
Get more info on 'Sigma Bond'.
|
External Link Exchanges
Do you know how hard it is to get a link from a large encyclopaedia? Well we're different and will prove it. To get a link from us just add the following HTML to your site on a relevant page:
<a href="http://sigma_bond.totallyexplained.com">Sigma bond Totally Explained</a>
Then simply click through this link from your web page. Our crawlers will verify your link, extract the title of your web page and instantly add a link back to it. If you like you can remove the words Totally Explained and embed the link in article text.
As long as your link remains in place, we'll keep our link to you right here. Please play fair - our crawlers are watching. Your site must be closely related to this one's topic. Any kind of spamming, dubious practises or removing the link will result in your link from us being dropped and, potentially, your whole site being banned. |
