Allotropes of Carbon

Question 1

What is an allotrope?

Answer 1

Allotrope: Different form of the same element.

Question 2

What kind of bond do carbon atoms form?

How many can it form?

Answer 2

4 Covalent bonds

Question 3

Explain the bonds in diamond.

Answer 3

• Diamond has a giant covalent structure.
• Each carbon bonds to 4 carbon atoms by covalent bonds.
• There are no delocalised electrons because all of them are bonded.

Question 4

What are the 3 properties of diamond?

Answer 4

• Hard
• High melting and boiling point
• Can’t conduct electricity

Question 5

What are the uses of diamond?

Answer 5

• Jewelery
• Drills because it is hard

Question 6

Explain the bonds in graphite.

Answer 6

• Graphite forms a giant covalent structure
• Each carbon is bonded to 3 carbon atoms by covalent bonds.
• Forms layers of hexagonal rings.
• Each carbon atom has a “spare electron.”
• All spare electrons form “electron cloud” of delocalised electrons.
• Layers can slide easily from delocalised electrons

Question 7

Explain why graphite is soft and slippery.

Answer 7

• Aranged in layers w/ no strong covalent bonds.
• The delocalised electrons creates weak force of attraction (keeps structure together.)
• So, layers slide easily.

Question 8

What are 3 the properties of graphite?

Answer 8

• High melting + boiling point.
• Very soft and slippery
• Good conductor of heat and electricity because of delocalised electrons.

Question 9

What are the uses of graphite?

Answer 9

• Used for pencils (layers slide easily)
• Lubricants

Question 10

Explain why graphene is strong.

Answer 10

• Has 3 strong covalent bonds
• Giant covalent structure: loads of them.
• Require a lot of energy to break.

Question 11

What is graphene’s bonding, properties, uses?

Answer 11

• Graphene is a single layer of graphite.
• Good conductor of electricity
• Uses: Electronics, composites *(strong + lightweight) *

Question 12

What are fullerene’s bondings and properties?

Answer 12

• A graphene layer, wrapped to make hollow tube.
• Hexagonal rings–> could contain 5/7 atoms.
• Buckminsterfullerene (C₆₀) - spherical shape.
• Carbon nanotubes are cylindrical fullerenes.
• Have delocalised electrons so can conduct electricity.

Question 13

What are giant covalent structures?

Answer 13

• Large structures made of non- metals bonded covalently.

Question 14

Explain why Giant covalent molecules are always solid at room temp.

Answer 14

• They have many strong covalent bonds
• High melting + boiling point

Question 15

Explain why diamond is hard.

(2 points)

Answer 15

• Have 4 strong covalent bonds
• Giant covalent structure: have loads of them.

Question 16

What is the bonding in silicon dioxide?

Answer 16

• Each silicon is bonded to 4 oxygens.
• Each oxygen is bonded to 2 silicons

(IN GIANT COVALENT STRUCTURE FORM)

Question 17

Explain why silicon dioxide has a high melting point.

Answer 17

• Has many strong, covalent bonds
• Require a lot of energy to break.

Question 18

Give 2 uses for silicon dioxide?

Answer 18

• Used in bags to absorb moisture
• Component of glass

Question 19

What are the uses of fullerenes?

Answer 19

• Delivering drugs to SPECIFIC places in the body.
• Lubricants (can roll around)
• Catalysts (large surface area to volume ratio.)

Question 20

Why are nanotubes good conductors?

Answer 20

• Delocalised electrons can move up and down hollow tube.

Question 21

What can carbon nanotubes be used in because they have a high tensile strength?

Answer 21

• Tennis rackets.

Question 22

What are 2 properties of carbon nanotubes?

Answer 22

1.) High tensile strength
2.) Good conductors of heat + electricity.

Question 23

Why can fullerenes be used in lubricators?

Answer 23

• They can roll so spread around.

Question 24

Q.)

Silicon dioxide has a very high melting point. Other substances are added to silicon dioxide to make glass. Why does glass melt at a lower temperature?

Answer 24

• The impurities distrupt the lattice structure.

Question 25

Why do buckerminster fullerenes have low melting and boiling points?

Answer 25

• Weak intermolecular forces between the fullerene balls.

Question 26

If graphite has weak intermolecular forces, why does it have a high melting and boiling point?

Answer 26

• Has many of these intermolecular forces: giant covalent sturcture.
• Many covalent bonds also

Question 27

Suggest why buckerminster fullerene is a good lubricant.

Answer 27

• Spherical
• Can roll

Question 28

As well as fullerenes being made of hexagonal rings what else can they be made up of (carbon atom number)?

Answer 28

• 5 or 7 carbon atoms

Question 29

What does high length to diameter ratio mean?

Answer 29

• Cyliandrical fullerenes and carbon nanotubes are very long even though they may be having a small diameter. creates low weight.

Question 30

Q.)

Graphite is softer than diamond.
Explain why.

Answer 30

• Graphite has layers that can easily slide.
• Because there are weak intermolecular forces between the layers.
• In Diamond, Each carbon atom is bonded to 4 others by covalent bonds.
• So diamond is rigid no layers can slide

Question 31

How is graphite similar to metals?

Answer 31

• Graphite is similar to metals because it has delocalised electrons.