Giant covalent structures

Question 1

What are the boiling points of giant covalent structures

Answer 1

Substances that consist of giant covalent structures are solids with very high melting and boiling points.

Question 2

how are all the atoms linked

Answer 2

all the atoms in a giant covalent are linked to other atoms by strong covalent bonds, therefore they have a high melting/boiling point

Question 3

properties of giant covalent structures

Answer 3

• High melting and boiling points (because of lots of bonds to break)
  -insoluble in water
  -hard
• do not conduct electricity — because they have no free electron (except for graphite).

Question 4

what are covalent compounds between

Answer 4

non-metals and non-metals

Question 5

what happens when they bond

Answer 5

electrons are shared and bonds are formed. No ions are formed

Question 6

Examples of giant covalent structures

Answer 6

-Diamond
-graphite
-silicon dioxide

Question 7

Answer 7

Diamond

Question 8

Answer 8

Fullerenes

Question 9

Answer 9

Graphite

Question 10

Answer 10

Carbon nanotube

Question 11

what is this

Answer 11

covalent structure

Question 12

what happens when giant covalent bonds are melted

Answer 12

It’s hard to break them since they have many strong bonds. But when they melt, the intermolecular forces break and the atoms split.

Question 13

Properties of carbon nanotubes

Answer 13

• high tensile strength because of the strong covalent bonds
• high electrical/ thermal conductivity because one electron form each carbon atom is localised and therefore al of these delocalised electrons can move throughout the whole structure allowing carbon nanotubes to conduct thermal energy
  -high melting and boiling points due to many strong covalent bonds that require lots of energy to break

Question 14

What is a fullerenes

Answer 14

-Molecules of carbon shaped like closed tubes, or hollow balls

Question 15

What are fullerenes used for

Answer 15

• drug delivery: they can form a structure around an atom or molecule
• Industrial catalysts: They have a big surface area
• lubricants: large surface area, due to ration of their nano particles

Question 16

What is silicon dioxide

Answer 16

• sometimes called silica — it’s what sand is made of
• each grain of sand is one giant structure of silicon and oxygen

Question 17

What’s a nanotube, describe it’s structure

Answer 17

• Formed from fullerenes and they are tiny carbon cylinders
• The ration between the length and the diameter of nanotubes is very high

Question 18

What are the properties of nanotubes

Answer 18

• conduct electricity and thermal energy
• high tensile strength (don’t break when stretched)

Question 19

What can nanotubes be used for

Answer 19

• electronics
• strengthen materials — because they don’t add much weight, e.g. tennis racket frames