Solids

Question 1

Substance in solid phase

Answer 1

Often has particles which are close together and fixed in position in lattice structure

Question 2

Types of solids

Answer 2

• Ionic solids
• Metallic solids
• Atomic (Covalent Network Solids)
• Molecular Solids

Question 3

Atomic Network Solids

Answer 3

• Consist of strong covalent bonds
• Bonds are between atoms
• Diamond, graphite and buckminsterfullerene are allotropes

Question 4

Examples of Atomic Network Solids

Answer 4

• Diamond
• Graphite
• C60 (Buckminsterfullerene)
• SiO₂ (Silicon Dioxide - beach sand)
• SC (Silicon Carbide)

Question 5

Diamond

Answer 5

• Very high melting and boiling point because of giant molecules and strong covalent bonds
• Tetrahedral
• Each Carbon atom forms 4 strong covalent bonds (diamond very hard)
• Does not conduct electricity (all valence electrons are involved in bonding, no free electrons)

Question 6

Graphite

Answer 6

• Planar 6-sided rings
• Each Carbon atom is covalently bonded to three other atoms
• The only non-metal conductor of electricity
• Conducts electricity because only 3 of it’s valence electrons are involved in bonding, one free electron carries charge
• Soft as the planes are able to slide over each other

Question 7

Silicon Carbide (SiC)

Answer 7

• Tetrahedral structure (same as diamond)
• Each Carbon atom is bonded to 4 silicon atoms and each silicon atom is bonded to 4 carbon atoms

Question 8

Silicon Dioxide (SiO₂)

Answer 8

• Tetrahedral structure (same as diamond)
• Each silicon atom is bonded to 4 oxygen atoms and each oxygen atom is bonded to 2 silicon atoms
• AKA Quartz (sea sand)

Question 9

Buckminsterfullerene (C₆₀)

Answer 9

• AKA buckyball
• 60 Carbon atoms form shape of ball, carbon atom at each corner of 20 hexagons and 12 pentagons

Question 10

Uses for fullerenes

Answer 10

• Catalyst
• Lubricants
• Used in nanotubes for strengthening materials/used as a way of delivering drugs into body

Question 11

Molecular Solids

Answer 11

• Forces holding this type of solid together: van der Waal’s forces (relatively weak)
• Molecular compounds have relatively low melting points and boiling points (can vary depending on intermolecular force)

Question 12

Examples of Molecular Solids

Answer 12

• Ice (water) -> H₂O molecules
• Dry Ice -> CO₂ molecules
• Iodine -> I₂ molecules
• HBr -> HBr molecules

Question 13

Ice

Answer 13

• Van der Waals force: Hydrogen bonding
• Lots of space in hexagonal structure (therefore ice floats)

Question 14

Iodine

Answer 14

• Diatomic
• Van der Waals force: London forces (therefore sublimes at room temperature)
• Non-conductor of electricity
• Low melting point (weak intermolecular forces)

Question 15

Dry Ice

Answer 15

• Van der Waals force: London Forces (very weak) because its non-polar
• Sublimes at room temperature
• Non-conductor if electricity

Question 16

Difference between Atomic Network Solids and Molecular Solids

Answer 16

Atomic: intramolecular forces are covalent and intermolecular forces are covalent
Molecular: intramolecular forces are covalent and intermolecular forces are Van der Waal’s