Chemistry 121122 ISOMERS Isomers The prefix iso means

Chemistry 121/122 ISOMERS

Isomers �The prefix “iso-” means same parts. How does this help with the definition of the term isotope? �Some hydrocarbons only differ in their structural arrangement, not their structural formula Ex. C 5 H 8 has three structural arrangements �When the arrangements are different but the formula is the same, the molecules are referred to as structural isomers They have different physical characteristics

Stereoisomers – Geometric Isomers �Stereoisomers exist when the order of the atoms is identical but their positions in space is different bond angles are different �Geometric isomers are joined in the same order but differ in the orientation of groups around a double bond There are two configurations – trans (opposite sides) and cis (same sides) They are possible whenever each carbon of the double bond has at least one substituent

Stereoisomers – Optical Isomers �Optical isomers exist when a carbon atom has four different atoms or groups attached, the molecule is asymmetric �They are mirror images of each other – such as in looking at yourself in the mirror �The mirror images will never be identical unless bonds are broken �Conceptual Problem 22. 4

For the remainder of class… �Question 25 on page 707 �Worksheet �Quick Lab – Page 707 To be passed in Monday Complete questions 1 – 3 under the analyze and conclude section Draw and name the nine structural isomers of heptane (C 7 H 16) Bonus Assignment (add 5 points to your Test), draw and name the 18 isomers of octane – due Monday