C2.3 - p1

Question 1

what is an allotrope? (2)

Answer 1

• a form of an element in the same state (1)
• but with different atomic arrangements (1)
  (ie. diamond, graphite)

Question 2

state uses of graphene (1 layer thick, very strong and conducts electricity)

Answer 2

• solar panels
• batteries
• increases a material’s strength without adding much weight (composite materials)

Question 3

what are fullerenes?

Answer 3

structures that have hollow shapes

Question 4

describe the shape of fullerenes

Answer 4

• shaped as tubes/balls

Question 5

what can spherical fullerenes be used for? (3)

Answer 5

• catalysts
• lubricants
• vectors for drugs into body (can pass through cell membranes)

Question 6

what happens when chemical bonds form? (in terms of energy)

Answer 6

stored chemical energy is transferred to the surroundings

Question 7

what are the bonds in simple molecules?

Answer 7

covalent forces between atoms, intermolecular forces between molecules

Question 8

give examples of ionic compounds

Answer 8

sodium chloride

Question 9

give examples of giant covalent structures

Answer 9

silica, diamond

Question 10

give examples of simple molecules

Answer 10

oxygen, water,

Question 11

what forces break when simple molecules boil/melt

Answer 11

the weak forces between the molecules, not the strong covalent bonds between each atom

(H20-H20) becomes H20 H20

Question 12

what is the word used to describe when substances go directly from a solid to a gas?

Answer 12

sublimation

Question 13

what is the word used to describe when substances go directly from a gas to a solid?

Answer 13

deposition

Question 14

what determines whether a substance is brittle or malleable? (particles) (2)

Answer 14

how easily the particles in the substance can change (1) their positions in the lattice structure (1)

Question 15

Evaluate why metals are malleable. (3)

Answer 15

attracting force between electrons and metal ions remain strong (1)
so bonds do not break (1)
instead layers of ions only slide over each other (1)

Question 16

are giant covalent structure brittle?

Answer 16

yes

Question 17

-

Answer 17

-

Question 18

Explain why ionic compounds are brittle. (3)

Answer 18

• in a giant ionic lattice, ions are arranged alternating with charges (1)
• when a force is applied, ions slide over each other (1)
• so new arrangement has like charges together, and so they repel (1) (pushing either side apart, and therefore breaking)

Question 19

what allows a substance to conduct electricity?

Answer 19

whether or not it has delocalised electrons that can move

Question 20

why do metals conduct electricity? (1)

Answer 20

it has delocalised electrons that are free to move (1) (through the lattice to carry the charge)

Question 21

when do ionic compounds conduct electricity, and why?

Answer 21

• when molten/in the liquid state/ dissolved in water (1)
• ions are then free to move (1)

Question 22

what are the size of nanoparticles?

Answer 22

between 1 and 100nm long

Question 22

what are the size of coarse particles?

Answer 22

2,500 and 10,000nm long

Question 23

disadvantages of using nanoparticles? (3)

Answer 23

• so small can be breathed in/absorbed
• may take a long time to break down
• difficult to predict (not much information known)

Question 24

what are properties of nanoparticles because of a large surface area to volume ratio?

Answer 24

• efficient (less quantity used to make product)

Question 25

what can nanoparticles be used for? (3)

Answer 25

• catalysts (larger surface area)
• medicine/drugs (deliver to a specific area of body)
• self-cleaning windows
• cosmetics (so small they are transparent)

Question 26

why are nanoparticles good for cosmetics?

Answer 26

• so small that light passes through
  (transparent)

Question 27

why are nanoparticles good for cosmetics? (1)

Answer 27

They can be absorbed much deeper into the skin