This seminar presentation discusses the classification of molecules into point groups based on their symmetry elements and operations. Molecules are classified as having low, high, or special symmetry depending on the number and type of their symmetry elements. Examples are provided to demonstrate predicting molecular geometry and identifying the point group.
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point group).pptx
1. SEMINAR ON -
CLASSIFICATION OF MOLECULES INTO POINT GROUPS
PRESENTED BY
NIKHIL J LAKKAD
UUP212520
1ST M.Sc. CHEMISTRY
DEPARTMENT OF CHEMISTRY
2. CONTENTS
• INTRODUCTION –
• SYMMETRY OPERATION
• SYMMETRY ELEMENTS
• POINT GROUPS
• CLASSIFICATION OF POINT GROUP
• MOLECULES WITH LOW SYMMETRY
• MOLECULES WITH HIGH SYMMETRY
• MOLECULES WITH SPECIAL SYMMETRY
• EXAMPLES
• REFERANCES
3. INTRODUCTION
The arrangement of atoms or groups atoms in a molecule are described
formally in terms of symmetry aspects. This symmetry arises because of
atoms or groups of atoms it’s repeated in a regular rhythmic way to form a
pattern.These are described by symmetry operations, which are intricately
linked with symmetry elements.
4. SYMMETRY OPERATIONS
• Symmetry operation can be simply understood as a geometrical
manipulation in such a way that an equivalent or indistinguishable
configuration of the molecule always results after the operation is
performed. The new product configuration need not always be identical 2
third of the order, but it is sufficient if it is equivalent.
5. SYMMETRY ELEMENTS
While symmetry operations are some physical manipulation to get equivalent
configuration a symmetry element is a geometrical entity. there are five types
of symmetry elements
• Rotational axis of symmetry, Cn
• Plane of symmetry. σ
• improper rotation axis of symmetry, Sn
• Inversion centre or centre of symmetry, i
• Identity element, E
6. POINT GROUPS
• These are the methods of classifying the shapes of molecules according to
their symmetry elements.They are called point groups because we consider
that all symmetry elements pass through a point and it remains unchanged.
This point is also known as the centre of gravity of the compound.
• This point remains unshifted during all the operations generating these
elements hence the grouping of such elements is identified as a point group.
8. • Based on the previous table the whole range of available molecules is
divided into three types
• Molecules of low symmetry
• molecules of high symmetry
• Molecules of special symmetry
10. REFERANCE
• Symmetry and spectroscopy of molecules
- KVeera Reddy
• Inorganic chemistry - Principles of structure and reactivity
- James E. Huheey
• https://www.staff.ncl.ac.uk/j.p.goss/symmetry/Molecules_pov.html
• https://chem.libretexts.org/Bookshelves/Inorganic_Chemistry/Supplemental_Mod
ules_and_Websites_(Inorganic_Chemistry)/Advanced_Inorganic_Chemistry_(Wiki
book)/01%3A_Chapters/1.01%3A_Symmetry_Elements
