Unit 3: Section 1 - Introduction to Organic Chemistry

Question 1

What does the general formula show?

Answer 1

An algebraic formula that can describe any member of a family of compounds.

Question 2

What does the empirical formula show?

Answer 2

The simplest ratio of atoms of each element in a compound.

Question 3

What does the molecular formula show?

Answer 3

The actual number of atoms of each element in a molecule.

Question 4

What does the structural formula show?

Answer 4

Shows the atoms carbon by carbon, with the attached hydrogens and functional groups.

Question 5

What does the skeletal formula show?

Answer 5

Shows the bonds of the carbon skeleton only, with any functional groups.

Question 6

What does the displayed formula show?

Answer 6

Shows how all the atoms are arranged, and all the bonds between them.

Question 7

Define a homologous series.

Answer 7

A group of compounds that contain the same functional group. They can all be represented by the same general formula.

Question 8

What is the difference between the structures of amines and amides?

Answer 8

Amine:
e.g methylamine
CH3NH2

Amide:
e.g ethanamide
CH3CONH2

Question 9

How do you know if two or more molecules are isomers of each other?

Answer 9

They have the same molecular formula but the atoms are arranged differently.

Question 10

Define a structural isomer.

Answer 10

They have the same molecular formula but different structural formulas.

Question 11

Describe the three structural isomers.

Answer 11

Chain isomers have different arrangements of the carbon skeleton (some are straight and others are branched).

Positional isomers have the same skeleton and the same atoms or groups of atoms attached however the atom or group of atoms is attached to a different carbon atom.

Functional Group isomers have the same atoms arranged into different functional groups.

Question 12

Define a stereoisomer.

Answer 12

They have the same structural formula but a different arrangement in space.

Question 13

Define planar.

Answer 13

The atoms are on the same plane

Question 14

Double bonds can’t _____.

Answer 14

Rotate

Question 15

What is a Z-isomer?

Answer 15

The Z-isomer has the same groups either abover or below the double bond.

Question 16

What is an E-isomer?

Answer 16

The E-isomer has the same groups positioned across the double bond.

Question 17

Describe and explain the Cahn-Ingold-Prelog priority rules to identify an E/Z isomer.

Answer 17

1. Assign a priority to the two atoms attached to each of the two carbons in the double bond.
2. To do this, you look at the atoms that are directly bonded to each of the double bond carbons. The atom with the highest atomic number on each carbon is given higher priority.
3. To work out which isomer you have, look at how the two higher priority groups are arranged

Question 18

When do you use the Cahn-Ingold-Prelog priority rules?

Answer 18

When you have three or four different groups in an alkene.