1. ISOMERS Chemistry 122

2. 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 4 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

3. 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

5. 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

6. For the remainder of class… Questions 18 – 19, page 706, 25 on page 707 Guided reading – up to section 22.3 Quick Lab – Page 707  To be passed in Thursday  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 Chapter 19 Test), draw and name the 18 isomers of octane – due Thursday