What is Isomers: Definition and 58 Discussions

In chemistry, isomers are molecules or polyatomic ions with identical molecular formulas — that is, same number of atoms of each element — but distinct arrangements of atoms in space. Isomerism is existence or possibility of isomers.
Isomers do not necessarily share similar chemical or physical properties. Two main forms of isomerism are structural or constitutional isomerism, in which bonds between the atoms differ; and stereoisomerism or spatial isomerism, in which the bonds are the same but the relative positions of the atoms differ.
Isomeric relationships form a hierarchy. Two chemicals might be the same constitutional isomer, but upon deeper analysis be stereoisomers of each other. Two molecules that are the same stereoisomer as each other might be in different conformational forms or be different isotopologues. The depth of analysis depends on the field of study or the chemical and physical properties of interest.
The English word "isomer" () is a back-formation from "isomeric", which was borrowed through German isomerisch from Swedish isomerisk; which in turn was coined from Greek ἰσόμερoς isómeros, with roots isos = "equal", méros = "part".

View More On Wikipedia.org
  1. C

    What Are Optical Isomers and What Causes Their Effects?

    Optical isomers... Optical isomers are so called because they apparently "have differing effects on polarised light" - what exactly happens and why? Thanks in advance. :smile:
  2. N

    How many isomers does C4H9Br have?

    The book says 4, but isn't there 5? 1) CH3-CH2-CH2-CH2-BR 2) CH3-CH2-CH-CH3 BR 3) CH3-CH-CH2-BR CH3 4) CH3-CH2-CH-BR CH3 CH3 5) CH3-C-CH3 BR ugh..sorry i can't get the computer...
  3. X

    Chlorination of (R)-2-Chlorobutane: Meso vs Racemic Isomers

    When (R)-2-chlorobutane is chlorinated, we obtain some 2,3-dichlorobutane. It consists of 71% meso isomer and 29% racemic isomers. Explain why the mixture need not be 50:50 meso and (2R,3R)-2,3-dichlorobutane
  4. N

    Draw and name all constitutional isomers

    I am doing my Organic Chem homework and need help. It asks: Draw and name all constitutional isomers with formula C9H20 which have one quaternary carbon and one or more ethyl groups (there are three). What are they and how do I find them?
  5. P

    Isomers of C9H20: Find & Learn More

    -c-c-c-c-c-c-c-c-c nonane c | -c-c-c-c-c-c-c-c- 2-methyloctane c | -c-c-c-c-c-c-c-c- 3-methyloctane c | -c-c-c-c-c-c-c-c- 4-methyloctane c | -c-c-c-c-c-c-c- 2,2 dimethylheptane | c does anyone...
  6. P

    Discover All Isomers for C9H20 for Beginners

    hey I am trying to figure out all the isomers for C9H20...im getting kind of frusterated so if anyone can help me find them or just tell me how thatd be awesome! thanx! :smile:
  7. G

    How many isomers can be formed from C7H16?

    I was given a molecular formula C7H16 and asked to find all possible isomers. I know there are nine because the question said it. But I am just wondering how to find all isomers correctly without repeating myself. Is there a way to do this mathematically or a general rule that makes it easier?
  8. H

    Sequence for Isomers of Alkanes

    Today in my chemistry glass, my teacher was talking about isomers in organic chemistry. I was wondering if there is a formula or a way to predict the number of isomers each alkanes compound has.
Back
Top