Ch 2 Alkanes and Organic Nomenclature

Question 1

Hydrocarbon

Answer 1

carbon and hydrogen only

Question 2

4 Cs of chemical structure

Answer 2

Composition - elements
Constitution - connectivity
Configuration - arrangement
Conformation - arrangement with bonds on different atoms

Question 3

Alliphatic hydrocarbons

Answer 3

Alkanes - 1x bond (C n, H 2n+2)
Alkene - 2x bond (C n, H 2n)
Alkyl - 3x bond (C n, H 2n-2)

Question 4

Aromatic hydrocarbons

Answer 4

have benzene ring

Question 5

n-Alkane (“normal”)

Answer 5

-unbranched alkane

Question 6

Skeletal structure

Question 7

Cycloalkanes

Answer 7

Alkanes in a circular chain
-have fewer Hs

Question 8

Isomers

Answer 8

different compounds with the same molecular formula
-connectivity: constitutional/structural isomers

Question 9

IUPAC

Answer 9

slides 13 - 23

Question 10

Cycloalkane nomenclature

Answer 10

IUPAC + cyclo

Question 11

Carbon classification

Answer 11

Primary - bonded to one other C
Secondary - two other Cs
Tertiary - three other Cs
Quaternary - four other Cs

(same name applies to their hydrogens)

Question 12

Conformations!

Answer 12

-very fast
Rotating about a single bond (double and triple are too close to move around); leads to different dihedral angles
Ways to show:
-Newman projection
-Line and wedge
-Sawhorse projection

Eclipsed conformation: torsional strain
*usually are just transition states (not set)

Staggered conformation: more stable than eclipsed (each atom has own room for electrons)
-Gauche (60 degrees)
-Anti (180 degrees)
*favored
*most stable conformation of staggered is favored

-van der Waals repulsions happen when radii are squished too close (less stable)

Question 13

Alkanes

Answer 13

Boiling Point
-unbranched: BP increases with each carbon

Melting Point
-used to identify compounds
-narrow melting point: purer
-increases with carbon number
-lowers with branching (more SA)
-symmetry: very high MP

Dipole Moment
-negligible dipole moments
-nonpolar

Solubility
-insoluble in water

Density
-less dense than water (many oils are Alkanes)

Combustion
-least reactive of organic compounds
-react quickly with O2 to make CO2 and H2O

*make many functional groups

Question 14

Functional Groups

Answer 14

characteristically bonded group of atoms

‘R’ - a generic functional group
‘Ph-‘ - phenyl group
‘Ar’ - commonly substituted ring (Aromatic)

Question 15

Compound Classes

Answer 15

compounds with same functional group