MindMap Gallery Structural Chemistry-Molecular Symmetry Mind Map
This is a mind map about structural chemistry-molecular symmetry, including symmetry operations and symmetry elements, the concept of groups, point groups, etc.
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This is a mind map about bacteria, and its main contents include: overview, morphology, types, structure, reproduction, distribution, application, and expansion. The summary is comprehensive and meticulous, suitable as review materials.
This is a mind map about plant asexual reproduction, and its main contents include: concept, spore reproduction, vegetative reproduction, tissue culture, and buds. The summary is comprehensive and meticulous, suitable as review materials.
This is a mind map about the reproductive development of animals, and its main contents include: insects, frogs, birds, sexual reproduction, and asexual reproduction. The summary is comprehensive and meticulous, suitable as review materials.
molecular symmetry
Symmetry operations and symmetry elements
Identity Elements and Identity Operations
A motion that does not move or rotates 360 degrees is called an identity operation, and the corresponding symmetry element is called an identity element, denoted as E
Rotation axes and rotation operations
The rotation operation is the operation of rotating the molecule around a certain axis to restore it, denoted as C
Mirror and reflection operations
If there is a plane in the molecule that reflects the two halves of the molecule to each other and can restore the molecule, then the plane mirror is a mirror.
Symmetry center and inversion operation
If you extend a straight line from any atom in the molecule to the center of symmetry, you will find another identical atom on the other side equidistant from the center of symmetry. The symmetry operation corresponding to the symmetry center is called inversion or inversion.
Rotation reflection operations and reflections
concept of group
definition
A collection of elements that are related to each other according to certain operating rules. The elements can be operations, matrices, operators, numbers, etc.
To meet the conditions
Closeness, main operation, inverse operation, associativity
group multiplication table
If we know that the elements of a group are n and that all possible products are n2, then the group is completely and uniquely determined. n is the order of the group, that is, the number of equivalent parts in the object. List the products of group elements to get a multiplication table. Assume that the column element is A and the row element is B, then the product is AB, column x is row, row element B acts first, and column element A acts later.
combination of symmetrical elements
When two symmetrical elements exist at the same time in a certain relative position, a third symmetrical element must be derived, which is called a combination of symmetrical elements. The combination of symmetrical elements obeys certain combination principles.
The product of two rotations must be another rotation
The combination of two mirrors is a rotation operation
The combination of an even axis of rotation and a mirror perpendicular to it
Point group
axisless group
C1 group
E, the molecule is completely asymmetrical
This group
In addition to E, there is also a group of symmetry centers
Cs group
In addition to E, it also contains a symmetry plane
single axis group
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Dihedral group
Dn group
In order n order group, in addition to the main axis Cn, there are n secondary axes C2 perpendicular to it.
Dnh group
4n order group, on the basis of Dn, there is also a mirror surface perpendicular to the main axis
Dnd group
The 4n order group, based on Dn, adds n mirror surfaces that contain the main axis and bisect the angle between the secondary and secondary axes.
high symmetry group
Point group containing more than two higher-order axes Cn
Regular tetrahedron group: T, Td, Th
Cube or octahedron group
Oh, Oh
icosahedral group
I,Ih
Molecular symmetry and molecular dipole moment and optical rotation
Groups with dipole moments: Cn, Cs, Cnv
Optically active groups: Cn, Dn