Bonding: Properties of Materials

Question 1

The Four Crystal Structures

Answer 1

• Ionic
• Metallic
• Macromolecular (giant covalent)
• Molecular

Question 2

Properties of Giant Ionic Structures

Answer 2

• Type of bonding
- Ionic

• Melting/boiling point

• Generally high
• This is due to having to break lots of strong electrostatic forces of attraction between oppositely charged ions

• Conductivity

• As solids - no as ions can’t move
• Molten or solution - yes as the ions are free to move and carry a charge

• Is it soluble in water?
- Yes

Question 3

Properties of Metallic Structures

Answer 3

• Type of bonding
- Metallic

• Melting/boiling point
- Usually high due to having to break lots of strong electrostatic forces of attraction between positive ions and a sea of delocalised electrons

• Conductivity
- Yes there are delocalised electrons to carry the charge

• Is it soluble in water?
- No

Question 4

Properties of Simple Molecular Structures

Answer 4

• Type of bonding
- Covalent

• Melting/boiling point
- Usually low due to having to break weak intermolecular forces between molecules requiring little energy

• Conductivity
- No as all electrons involved in bonding

• Is it soluble in water?
- Depends on how polar the molecules are

Question 5

Properties of Macromolecular Structures

Answer 5

• Type of bonding
- Covalent

• Melting/boiling point
- Very high due to having to break lots of strong covalent bonds requiring lots of energy

• Conductivity

• Diamond - no as all electrons involved in bonding
• Graphite - yes each carbon atom has one delocalised electron to carry the charge
• No (except for graphite)

• Is it soluble in water?
- No

Question 6

Melting & Boiling Covalent Substances

Answer 6

• Simple covalent substances

• To melt/boil simple covalent substances, the covalent bonds don’t break - only the intermolecular forces are broken
• The strong covalent bonds don’t have to be broken so simple covalent substances have relatively low melting/boiling points

• Giant covalent substances
- To melt/boil giant covalent substances, the covalent bonds need to be broken so they have very high melting/boiling points