Ch 4 Intro to Alkenes and Alkynes: Structure and Reactivity

Question 1

Nomenclature

Answer 1

Alkene = olefin
Alkyne = acetylene

*have similar physical properties (BP, MP, density, water solubility, dipole moment)

Question 2

Bond lengths

Answer 2

increase with decreasing s character (less tight molecules have longer bonds)

Question 3

Constitutional isomers

Answer 3

different with 2x bond placement (bonds are broken to turn into them)

Question 4

Stereoisomers

Answer 4

different in way the atoms are arranged in space (cis, trans, etc.)

stereocenter - carbon in a stereoisomer at which it moves into a different conformation

Question 5

E, Z

Answer 5

E - trans (high priority groups across from each other)
X - cis (high priority groups on same side)

High priority: higher atomic number, higher bond number

Question 6

Unsaturation Number

Answer 6

the number of rings and/or pi bonds in a molecule (each ring and pi bonds reduce the number of hydrogens by 2)

2C + 2 - H / 2
Halogens: 2C + 2 - (H + X) / 2