C5.1

Question 1

1. What does dry air consist of?

Answer 1

Dry air consists of gases, some of which are elements and some of which are compounds

Question 2

1. What is a compound?

Answer 2

-a compound is more than one type of atom bonded together

Question 3

1. What is an element?

Answer 3

-an element is one type of atom

Question 4

1. What are some examples of elements and compounds in dry air?

Answer 4

Elements: oxygen, nitrogen and argon
Compounds: carbon dioxide

Question 5

2. What are the approximate relative proportions of the main gases in the atmosphere?

Answer 5

78% nitrogen
21% oxygen
1% argon
0.04% carbon dioxide

Question 6

3. What are the symbols for the atoms and molecules of these gases in the air?

Answer 6

• nitrogen (N2)
• oxygen (O2)
• argon (Ar)
• carbon dioxide (CO2)

Question 7

4. What are most non-metal elements and most compounds between non-metal elements?

Answer 7

-molecular

Question 8

5. What is the melting and boiling points of molecular elements and compounds with small molecules like?

Answer 8

• low melting and boiling points
• because although held together by strong covalent bonds, they have weak intermolecular forces so it doesn’t take much energy to break them apart

Question 9

7. Molecular elements and compounds, such as those in the air, have low melting and boiling points? How does it affect their state at room temperature?

Answer 9

• because they consist of small molecules with weak forces of attraction between the molecules
• means they are liquids/ gases at room temperature

Question 10

8. Do pure molecular compounds conduct electricity? Why?

Answer 10

• They cant conduct electricity

- Because their molecules are not charged, so there are no free electrons or ions

Question 11

9. How do molecules bond?

Answer 11

-covalent bonding

Sharing electrons

Question 12

9. How do molecules bond through covalent bonding?

Answer 12

• atoms bond due to the electrostatic attraction between the positive nuclei of the atoms and the negative electrons shared between them
• share the electrons to fill up the outer shell

Question 13

10. What is the strength of covalent bonds in contrast to forces of attraction between small covalent molecules?

Answer 13

• covalent bonds are strong

- forces of attraction are weak