[Part 3]- C3- structure and bonding 🔗

Question 1

What is graphene ?

Hint: thick

Answer 1

• graphene is a single layer of graphite, which is one atom thick.

Question 2

What can you tell me about the properties of graphene ?

Hint: ⚡️💪

Answer 2

• graphene is a excellent conductor of electricity, because it has delocalised electrons that can carry an electrical charge throughout the whole structure.
• additionally, graphene is also extremely strong for its mass- this makes it useful for new materials.
• [graphene could even be used to flexible electronic displays on your sleeve; it can’t yet be made on an industrial scale. ]

Question 3

What are fullerenes ?

Hint: hollow

Answer 3

• fullerenes are molecules of carbon atoms, with hollow shapes.
• fullerenes usually have hexagonal rings of carbon atoms; fullerenes can also have rings with five or seven atoms.

Question 4

What is the name and molecular formula of the first fullerene to be discovered ?

Answer 4

• Buckminsterfullerene, was the first fullerene to be discovered and has the molecular formula C60. [it contains sixty carbon atoms, arranged in a hollow sphere. ]
• the carbon atoms in buckminsterfullerene, form rings with either six carbon atoms or with five carbon atoms.

Question 5

What can fullerenes be used for ?

Hint: 💊

Answer 5

• fullerenes can be used for a various number of reasons such as:
• pharmaceutical delivery- fullerenes can deliver pharmaceutical drugs into the body using Bucky onions.
• This is because the fullerene structure forms around other atoms or molecules, which is them trapped inside. This can be used to ‘cafe’ other molecules, therefore making it able to deliver drugs into the body.

Question 6

What are some other uses of fullerenes ?

Hint: ⚙️, ☢️

Answer 6

• lubricants in machines, to stop moving parts from grinding together.
• to deliver radioactive isotopes, to kill cancer cells.

Question 7

Can you think of any other uses for fullerenes ?

Hint: speed up

Answer 7

• fullerenes could be used as catalysts to speed up chemical reactions.
• this is because of their large surface area: volume ratio. [therefore catalyst molecules could be attached to fullerenes.]

Question 8

What are carbon nanotubes ?

Hint: long cylinders

Answer 8

• carbon nanotubes are fullerenes shaped into long cylinders, and have rings that are formed from six carbon atoms.

Question 9

What is one use of carbon nanotubes ?

Hint: reinforce

Answer 9

• one use of carbon nanotubes, is that they can be used to reinforce materials. For example [carbon fibre] tennis rackets.

Question 10

What are polymers ?

Answer 10

• polymers are made by joining together thousands of small, indentical molecules known as monomers.
• monomers are normally alkene molecules [e.g- ethene]

Question 11

Referring to ethene monomers, and polymers [polyethene]. What is the difference between the bonding of monomers 🆚 the bonding of polymers.

Answer 11

• monomers have a double carbon covalent bond; polymers have a single carbon covalent bond.

Question 12

What are some facts you can tell me about repeating units, in polymers ?

Hint: either side

Answer 12

• repeating units are drawn, instead of drawing out a long polymer molecule.
• the covalent bonds on either side have to extend out of the bracket.
• the little ‘n’ tells us that the polymer, contains a very large number of repeating units joined together. [n represents a large number]

Question 13

What can you tell me about the properties of polymers ?

Answer 13

• most polymers are solid at room temperature, since the intermolecular forces of attraction between the polymer molecules are relatively strong.
• Because the intermolecular forces between polymers are relatively strong, this takes a lot of energy to break these forces, meaning that polymers have a high melting point.

Question 14

What can you tell me about the bonding in metals ?

Answer 14

• metals consist of a giant structure of atoms, which are arranged in regular layers.
• metals have a strong electrostatic attraction between the sea of delocalised electrons, and the positive metal ions. This is called a metallic bond, which are strong.

Question 15

What are the properties of metals ?

Answer 15

• metals have a high melting and high boiling point. This is because, a great deal of energy is required to break the strong metallic bond.
• metals are excellent conductors of heat and electricity. This is because the delocalised electrons, can move throughout the whole structure, carrying an electrical charge, or thermal [heat] energy.

Question 16

Why are metals malleable and ductile ?

Answer 16

• metals are also malleable, because when they are hit, the layers of metal’s ions can slide over each other, but the delocalised electrons maintain the metallic bond- therefore the metal won’t break.
• also, metals are also ductile- [they can be drawn out into wires]- because when they are hit, the layers of metal’s ions can slide over each other, but the delocalised electrons maintain the metallic bond- therefore the metal won’t break.

Question 17

What is the structure of metals ?

Hint: sea

Answer 17

• metals consist of a giant structure, and are lattices of positively charged ions.
• They are arranged in [solid] regular layers, and the outer electrons of metals form a sea of delocalised electrons that are free to move, throughout the whole metal

Question 18

What are Alloys? And why are they harder than pure metals?

Hint: 🛝

Answer 18

• alloys, are are a mixtures of metal, with other elements (normally metals).
• Because the different size atoms distort the layers, this makes it more difficult for them to slide over each other.
• therefore, this is why alloys are harder than pure metals.

Question 19

What are the limitations of dot and cross diagrams ?

Hint: shape

Answer 19

• dot and cross diagrams don’t tell us about the shape of the molecule.
• [it’s very clear where the electrons are coming from because we use dots to represent the electrons from one atom, and we use crosses to represent the electrons from another atom. ]

Question 20

What are the limitations of the two-dimensional stick model ?

Hint: can’t tell, outer electrons

Answer 20

• because the covalent bond is shown as a stick, we can’t tell which electron in the bond came from which atom.
• moreover, stick diagrams give us no idea of outer electrons, that aren’t in bonds.
• two dimensional stick models, don’t give us accurate informations on the shape of the molecule.

Question 21

What are the limitations of the three-dimensional stick model ?

Hint: piece of paper

Answer 21

• it shows us the shape of the molecule; it tries to show a 3D shape on a 2D piece of paper.

Question 22

What are the limitations of the ball and stick diagrams, when showing giant ionic lattices ?

Hint: widely spaced

Answer 22

• although it allows us to clearly see the ions in three dimensions, the ions are shown as widely spaced; in reality, the ions are packed together.
• They also show only a tiny part, of the giant ionic crystal lattice- this is not a true representation of the sizes of these structures, since we are instead given a mistaken impression.

Question 23

What are the limitations of space-filling diagrams ?

Hint: show only

Answer 23

• space filling diagrams give us a better idea of how closely packed the ions are.
• ; it can be difficult, to see the three dimensional packing with a space filling diagram.
• They also show only a tiny part, of the giant ionic crystal lattice- this is not a true representation of the sizes of these structures, since we are instead given a mistaken impression.

Question 24

What are the properties of carbon nanotubes ?

Answer 24

• they have a high tensile strength, meaning they can be stretched without breaking.
• they are also excellent conductors of heat and electricity, possessing a high heat conductivity and high electrical conductivity.
• this is because of free delocalised electrons which can carry a charge throughout the whole structure

Question 25

Why do polymers generally have lower boiling points ?

Hint: weaker

Answer 25

• polymers generally have lower boiling points than ionic or giant molecular compounds because:
• the intermolecular forces are still weaker than ionic or covalent bonds.