c3: bonding

Question 1

how are covalent bonds formed

Answer 1

by atoms sharing electrons

Question 2

which type of atoms form covalent bonds between them

Answer 2

non-metals

Question 3

why do giant covalent substances have have high melting points

Answer 3

it takes a lot of energy to break the strong covalent bonds between the atoms

Question 4

why do small molecules have low melting points

Answer 4

only a small amount of energy is needed to break the weak intermolecular forces

Question 5

why do most covalent substances not conduct electricity

Answer 5

do not have delocalized electrons

Question 6

why do large molecules have higher melting points and boiling points than small molecules

Answer 6

the intermolecular forces are stronger in larger molecules

Question 8

explain why graphite is soft

Answer 8

layers are not bonded so they can slide over each other

Question 9

what is a graphene

Answer 9

one layer of graphite

Question 10

give 2 properties of graphite

Answer 10

strong
conducts electricity

Question 11

what is fullerene

Answer 11

hollow cage of carbon atoms arranged as a sphere or a tube

Question 12

what is a nanotube

Answer 12

hollow cylinder of carbon atoms

Question 13

give 2 properties of nanotubes

Answer 13

high tensile strength
conduct electricity

Question 14

give 3 uses of fullerene

Answer 14

lubricant’s
drug delivery (spheres)
high tech electronics

Question 15

what is an ion

Answer 15

atom that has lost or gained electrons

Question 16

which kinds of elements form ionic bonds

Answer 16

metals and non-metals

Question 17

name the force that holds oppositely charged ions together

Answer 17

electrostatic force of attraction

Question 18

when can ionic substances conduct electricity

Answer 18

when melted or dissolved

Question 19

why do ionic substances conduct electricity when melted or dissolved

Answer 19

ions are free to move and carry charge

Question 20

describe the structure of a pure metal

Answer 20

layers of positive metal ions surrounded by delocalized electrons

Question 21

describe the bonding in a pure metal

Answer 21

strong electrostatic forces of attraction between metal ions and delocalized electrons

Question 22

explain why pure metals are malleable

Answer 22

layers can slide over each other easily

Question 23

what are 4 properties of pure metals

Answer 23

malleable
high melting/boiling points
good conductors of electricity
good conductors of thermal energy

Question 24

why are metal good conductors of electricity and thermal energy

Answer 24

delocalized electrons are free to move through the metal

Question 25

what is an alloy

Answer 25

mixture of metal with atoms of another element

Question 26

explain why alloys are harder than pure metals

Answer 26

different sized atoms disturb the layers preventing them from sliding over each other

Question 27

how big are nanoparticles

Answer 27

1-100nm

Question 28

how are nanomaterials different from bulk materials

Answer 28

nanomaterials have much higher surface area-to-volume ratio

Question 29

what are nanoparticles used for

Answer 29

used in healthcare, electronics, cosmetics, and catalysts