Bonding/ Physical properties

Question 1

What are the 4 types of crystal structure?

Answer 1

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

Question 2

What is the structure of graphite like?

4 key points.

Answer 2

• Each carbon bonded to 3 other carbon atoms (4th electron is delocalised.)
• Arranged in layers of hexagonal rings.
• Delocalised electrons can move throughout the structure.
• Weak Van der Waals forces between the layers.

Question 3

What are the properties of graphite? State how the properties link to graphite’s structure?

5 main things.

Answer 3

• Graphite: good conductor of electricity –> delocalised electrons between layers can move throughout structure and carry current.
• High melting point –> lots of strong covalent bonds.
• Insoluble –> covalent bonds are too strong to break (in water.)
• Soft –> layers can slide over each other easily (weak Van der Waals forces between layers.)
• Low density –> layers are far apart.

Question 4

What is the structure of diamond?

Answer 4

• Each carbon is bonded to four other carbon atoms in tetrehedral shape.
• No delocalised electrons.

Question 5

Properties of diamond? How do properties link to diamond’s structure?

5 main points.

Answer 5

• Good conductor of heat: tightly packed, rigid arrangement of atoms.
• Can be cut to make gemstones (unlike graphite which is too soft/ slippery to be cut.)
• Very high melting point/ hard –> many strong covalent bonds.
• Doesn’t conduct electricity –> no delocalised electrons (to move/ carry the charge.)
• Insoluble: covalent bonds are too strong to break (in water.)

() - extra info for clarification

Question 6

Particles in solids

Answer 6

• Tightly packed
• Regular arrangement
• High density
• Particles vibrate in fixed positions
• Can’t be compressed

Question 7

Particles in liquids

Answer 7

• Loosely- packed
• Random arrangement
• High density
• Particles move freely.
• Very difficult to be compressed
• PARTICLES IN LIQUIDS HAVE MORE ENERGY THAN PARTICLES IN SOLIDS

Question 8

Particles in gases

Answer 8

• Particles are spaced out
• Random arrangement
• Low density
• Move freely
• Relatively easy to compress gases
• PARTICLES IN GAS HAVE MORE ENERGY THAN SOLIDS/ LIQUIDS.

Question 9

How many hydrogen bonds does each molecule in ice form?

Answer 9

• Each molecule in ice forms 4 hydrogen bonds.

Question 10

Explain the energy changes associated with
changes of state

Answer 10

• Solid –> liquid = looseing the IMF’s (requires less energy.)
• Liquid –> gas = breaking the IMF’s (requires more energy.)