The document discusses isomerism, a phenomenon where compounds share the same chemical formula but differ in structures and properties due to varied arrangements of atoms. It outlines types of isomerism, including structural isomerism (with subtypes like chain, position, functional, and metamerism) and stereoisomerism (which includes geometric and optical isomerism). Various examples illustrate the concepts of isomerism and its implications in organic chemistry.

1. Isomerism
By Prof. Liwayway Memije-Cruz

2. What is Isomerism?
 a phenomenon where
two or more compounds
have the same chemical
formula but possesses
different structural
formulas, that is, different
properties.
 mainly because of
different structural or
spatial arrangements.

3. Isomers
 each of two or more
compounds with the
same formula but a
different arrangement
of atoms in the
molecule and different
properties.
 compounds exhibiting
isomerism.

4. TYPES OF ISOMERISM

6. A. Structural or Constitutional Isomerism
 structural isomers have the same molecular formula but
different structures, as in how they are linked to each other.
 are molecules which have the same molecular formula but
have different connectivities (The Order They Are Put
Together).

7. Types of Structural Isomerism
1. Chain Isomerism
2. Position Isomerism
3. Functional Isomerism
4. Metamerism

8. Chain Isomerism
 Isomers are chain isomers when two or more compounds
have the same molecular formula but differ in the branching
of carbon atoms.
 Chain isomers are molecules with the same molecular
formula, but different arrangements of the carbon ‘skeleton’.
Organic molecules are based on chains of carbon atoms, and
for many molecules this chain can be arranged differently:
either as one, continuous chain, or as a chain with multiple
side groups of carbons branching off.
 Example: we can represent C5H12 as three compounds:
CH3CH2CH2CH2CH3– pentane

9. Chain Isomers

10. Position Isomerism
 Isomers are position isomers when the two
or more compounds differ in the position of
the functional group or substituent atoms.
 based on the movement of a ‘functional
group’ in the molecule.
 Example: we can represent C3H7OH in two
arrangements:
CH3CH2CH2OH -Propan-1-ol

11. Position Isomerism

12. Functional Isomerism
 Isomers are functional isomers when the two
or more compounds have an identical
molecular formula but differ in the functional
group present. These isomers are the
functional isomers.
 Also known as functional group isomers,
 Example: we can represent C3H6O as a ketone
and as an aldehyde.

13. Functional Isomerism

14. Metamerism
 exhibited by compounds due to the
presence of different alkyl chains on
either side of the functional group.
 Example: we can represent C4H10O
as ethoxyethane (C2H5OC2H5) and
methoxypropane (CH3OC3H7).

15. Metamerism

16. B. Stereoisomerism
 Stereoisomerism is a
phenomenon in which
compounds have the same
molecular formula but differ
in the relative positioning or
orientation of atoms in space.
 Stereoisomers are the
compounds exhibiting
stereoisomerism.
Types of
stereoisomerism:
1. Geometric
Isomerism
2. Optical Isomerism

17. Geometric Isomerism
 it is shown by molecules in which their spatial
positions are locked to each other due to the presence
of a ring structure or a double bond.
 also known as cis-trans isomerism or E-Z isomerism

18. Optical Isomerism
 optical isomers are isomers that
are mirror images of each other.
 molecules that differ three-
dimensionally by the placement
of substituents around one or
more atoms in a molecule.
 optical isomers were given their
name because they were first
able to be distinguished by how
they rotated plane-polarized
light.

19. Optical Isomerism

20. Bibliography
 https://www.embibe.com/study/concept-of-chain-
isomerism-concept?entity_code=KTIS78
 https://www.toppr.com/guides/chemistry/organic-
chemistry/isomerism/
 https://www.chemguide.co.uk/basicorg/isomerism/
structural.
 https://www.compoundchem.com/2014/05/22/typesof
isomerism/