Bonding

Question 1

Describe simple covalent bonding

Answer 1

• Strong covalent bonds with molecules
• Weak intermolecular forces of attraction between molecules
• Low mp & bp
• Does not conduct electricity in any state
• Most insoluble in water but soluble in organic solvents

Question 2

Describe giant molecular structure

Answer 2

• Giant covalent bonds between atoms in a large and extensive network of atoms
• eg. graphite in addition to strong covalent bonds between atoms, there are weak forces of attraction between LAYERS
• High mp/bp
• Does not conduct electricity in any state except graphite
• Insoluble

Question 3

Describe giant ionic lattice structure

Answer 3

• Strong ionic bond/electrostatic forces of attraction between the oppositely charged ions
• High mp & bp
• Conducts electricity in molten or aqueous states only
• Most are soluble in water
• Ionic compounds are generally hard

Question 4

Describe giant metallic lattice structure/ metallic bonding

Answer 4

• Strong metallic bond/electrostatic forces of attraction between metal cations and sea of delocalised electrons
• High mp & bp
• Conducts electricity in all states
• Malleable and ductile

Question 5

Explain why giant ionic lattice structure has high mp & bp & conducts electricity when molten/aqueous

Answer 5

High mp & bp
- Large amounts of energy required to overcome strong electrostatic forces of attraction between OPPOSITELY CHARGED ions in the giant ionic lattice structure

Conducts electricity in molten/aqueous only

• Conducts electricity in molten & aqueous state as there are free moving ions in those molten/aqueous solution of ionic compounds
• Cannot conduct electricity in solid state as ions are held in fixed positions and not free to move to conduct electricity
• soluble in water
• Ionic compounds are generally hard (SAME REASON AS HIGHMP & BP)

Question 6

Explain why simple molecular structure has low mp & bp and cannot conduct electricity

Answer 6

Low mp & bp
- Only a small amount of energy needed to overcome the weak intermolecular forces of attraction between the molecules (must specify what molecules in qns)

Does not conduct electricity

• Does not conduct electricity in all states as there are no free moving electrons or ions to carry a charge to conduct electricity.
• Insoluble in water, soluble in organic solvents

Question 7

Explain diamond structure

Answer 7

High mp & bp

• Each carbon atom is covalently bonded to 4 other carbon atoms in a tetrahedral arrangement.
• Large amount of energy is needed to overcome the strong and extensive carbon-carbon covalent bonds in the diamond structure

Cannot conduct electricity

• All the valence electrons of each carbon atom are used for covalent bonding. There are no free moving electrons for electrical conduction
• Diamond is hard as (REASON SAME AS HIGH MP & BP)

Question 8

Explain graphite structure

Answer 8

High mp & bp

• The carbon atoms are covalently bonded to 3 other carbon atoms in a hexagonal arrangement
• Large amount of energy is needed to overcome the strong carbon-carbon covalent bonds within the layers of the graphite structure

Conducts electricity

• 3 out of 4 electrons of each carbon atom are used for covalent bonding with other carbon atoms
• Each carbon atom has one non-bonding electron.
• Presence of free moving electrons for electrical conduction

Soft and slippery

• It is soft & slippery and used as a natural lubricant
• Between layers of carbon atoms, they are held by weak forces of attraction
• Little amount of energy is required to overcome these weak forces of attraction between the layers of carbon atoms.
• The layers are able to slide past each other easily, hence it is soft & slippery

Question 9

Explain silicon dioxide structure

Answer 9

• Large amount of energy is required to overcome the strong silicon-oxygen covalent bonds in the silicon dioxide structure
• All the valence electrons of silicon and oxygen atoms are used for covalent bonding,
  There are no free moving electrons to allow silicon dioxide to conduct electricity

Question 10

Explain giant metallic structure

Answer 10

High mp & bp
- Large amount of energy is needed to overcome the strong electrostatic forces between the metal cations and sea of delocalised electrons

Conducts electricity
- Sea of delocalised electrons are free to move within the metal lattice, allowing the metal to conduct electricity

Malleable & ductile
When a force is applied, regularly arranged layers of metal atoms can slide over each other easily through the sea of delocalised electrons.
No disruption to metallic bonding