Representing the formulae of organic compounds

Question 1

What does the molecular formula show?

Answer 1

The number and type of atoms of each element present in a molecule

It does not show how the atoms are joined together.

Question 2

What is the molecular formula of ethanol?

Answer 2

C2H6O

Ethanol contains two carbon atoms, six hydrogen atoms, and one oxygen atom.

Question 3

Define empirical formula.

Answer 3

The simplest whole-number ratio of the atoms of each element present in a compound.

Question 4

What is the empirical formula for alkenes?

Answer 4

CH2

There are always twice as many hydrogen atoms as carbon atoms in an alkene.

Question 5

What is the relationship between the molecular formula of glucose and its empirical formula?

Answer 5

Molecular formula: C6H12O6; Empirical formula: CH2O.

Question 6

What is a general formula?

Answer 6

The simplest algebraic formula for any member of a homologous series.

Question 7

What is a displayed formula?

Answer 7

A formula that shows the relative positioning of all the atoms in a molecule and the bonds between them.

Question 8

What is the molecular formula of 1-bromobutane?

Answer 8

C4H9Br.

Question 9

What does a structural formula show?

Answer 9

The arrangement of the atoms in a molecule and which groups are bonded together.

Question 10

What is the structural formula of butane?

Answer 10

CH3CH2CH2CH3.

Question 11

What does a skeletal formula represent?

Answer 11

A simplified organic formula showing only the carbon skeleton and functional groups.

Question 12

In a skeletal formula, what does a line represent?

Answer 12

A single bond.

Question 13

In a skeletal formula, what does the end of a line represent?

Answer 13

A —CH3 group.

Question 14

What is the significance of functional groups in skeletal formulae?

Answer 14

They must be included in the skeletal formula.

Question 15

What are some examples of cyclic and aromatic compounds?

Answer 15

• Cyclohexane
• Cyclohexene
• Benzene.

Question 16

How is a double bond represented in a skeletal formula?

Answer 16

By two parallel lines.

Question 17

What is the skeletal formula for 2-chlorobut-1-ene?

Answer 17

Includes a double bond between carbon atoms 1 and 2 and a chlorine atom on carbon 2.

Question 18

Fill in the blank: The displayed formula shows the _______ of all the atoms in a molecule.

Answer 18

[relative positioning]

Question 19

True or False: Different molecules can have the same molecular formula.

Answer 19

True.