In
chemistry
Chemistry is the scientific study of the properties and behavior of matter. It is a physical science within the natural sciences that studies the chemical elements that make up matter and chemical compound, compounds made of atoms, molecules a ...
,
molecule
A molecule is a group of two or more atoms that are held together by Force, attractive forces known as chemical bonds; depending on context, the term may or may not include ions that satisfy this criterion. In quantum physics, organic chemi ...
s with a non-collinear arrangement of two adjacent bonds have bent molecular geometry, also known as angular or V-shaped. Certain atoms, such as oxygen, will almost always set their two (or more)
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 atom ...
s in non-collinear directions due to their
electron configuration.
Water
Water is an inorganic compound with the chemical formula . It is a transparent, tasteless, odorless, and Color of water, nearly colorless chemical substance. It is the main constituent of Earth's hydrosphere and the fluids of all known liv ...
(H
2O) is an example of a bent molecule, as well as
its analogues. The bond angle between the two hydrogen atoms is approximately 104.45°.
Nonlinear geometry is commonly observed for other triatomic molecules and ions containing only main group elements, prominent examples being
nitrogen dioxide (NO
2),
sulfur dichloride (SCl
2), and
methylene (CH
2).
This geometry is almost always consistent with
VSEPR theory, which usually explains non-
collinearity of atoms with a presence of
lone pair
In chemistry, a lone pair refers to a pair of valence electrons that are not shared with another atom in a covalent bondIUPAC ''Gold Book'' definition''lone (electron) pair''/ref> and is sometimes called an unshared pair or non-bonding pair. Lone ...
s. There are several variants of bending, where the most common is AX
2E
2 where two covalent bonds and two lone pairs of the central atom (A) form
a complete 8-electron shell. They have central angles from 104° to 109.5°, where the latter is consistent with a simplistic theory which predicts the
tetrahedral symmetry of four sp
3 hybridised orbitals. The most common actual angles are 105°, 107°, and 109°: they vary because of the different properties of the peripheral atoms (X).
Other cases also experience
orbital hybridisation, but in different degrees. AX
2E
1 molecules, such as
SnCl2, have only one lone pair and the central angle about 120° (the centre and two vertices of an
equilateral triangle
An equilateral triangle is a triangle in which all three sides have the same length, and all three angles are equal. Because of these properties, the equilateral triangle is a regular polygon, occasionally known as the regular triangle. It is the ...
). They have three sp
2 orbitals. There exist also sd-hybridised AX
2 compounds of
transition metal
In chemistry, a transition metal (or transition element) is a chemical element in the d-block of the periodic table (groups 3 to 12), though the elements of group 12 (and less often group 3) are sometimes excluded. The lanthanide and actinid ...
s without lone pairs: they have the central angle about
90° and are also classified as bent. (See further discussion at
VSEPR theory#Complexes with strong d-contribution).
See also
*
AXE method
References
External links
3D Chem: Chemistry, Structures, and 3D MoleculesIndiana University Molecular Structure Center
{{MolecularGeometry
Stereochemistry
Molecular geometry