C3- Bonding

Question 1

How are covalent bonds formed?

Answer 1

by atoms sharing electrons

Question 1

Which types of atom form covalent bond between them?

Answer 1

non-metals

Question 2

Describe the structure and bonding of a small molecule

Answer 2

small numbers of atoms group together into molecules with strong covalent bonds between the atoms and intermolecular forces of between the molecules

Question 3

Describe the structure and bonding of polymers

Answer 3

many identical molecules joined together by strong covalent bonds in a chain with weak intermolecular forces between the chains

Question 4

Why do giant covalent substances have high melting points?

Answer 4

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

Question 5

Why do small molecules have low melting points?

Answer 5

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

Question 6

Why do large molecules have higher melting and boiling points than small molecules?

Answer 6

the intermolecular forces are stronger in large molecules

Question 7

why do most covalent substances not conduct electricity?

Answer 7

they have no delocalised electrons or ions

Question 8

Describe the structure and bonding in graphite

Answer 8

each carbon atom is bonded to three others in hexagonal rings arranged in layers- they have delocalised electrons and weak forces between layers

Question 9

Why can graphite conduct electricity?

Answer 9

the delocalised electrons can move through graphite

Question 10

Explain why graphite is soft

Answer 10

layers are not bonded so can slide over each other

Question 11

What is graphene?

Answer 11

one layer of graphite

Question 12

Give 2 properties of graphene

Answer 12

strong, conducts electricity

Question 13

What is a fullerene?

Answer 13

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

Question 14

What is a nanotube

Answer 14

hollow cylinder of carbon atoms

Question 15

Give two properties of nanotubes

Answer 15

conduct electricity, high tensile strength

Question 16

Give 3 uses of fullerenes

Answer 16

drug delivery (spheres), lubricants, high-tech electronics

Question 17

What is an ion

Answer 17

atom that has lost or gained electrons

Question 18

What kinds of elements form ionic bonds?

Answer 18

metals and non-metals

Question 19

What charges do ions from Groups 1 and 2 form?

Answer 19

Group 1 forms 1+, Group 2 forms 2+

Question 20

What charges do ions from Groups 6 and 7 form?

Answer 20

Group 6 forms 2−, Group 7 forms 1−

Question 21

Name the force that holds oppositely charged ions together

Answer 21

electrostatic force of attraction

Question 22

Describe the structure of a giant ionic lattice

Answer 22

regular structure with alternating positive and negative ions, held together by the electrostatic force of attraction

Question 23

Why do ionic substances have high melting points?

Answer 23

electrostatic forces of attraction between positive and negative ions is strong and requires a lot of energy to break

Question 24

why don't ionic substances conduct electricity when solid?

Answer 24

ions are in fixed positions so cannot move, there are no delocalised electrons

Question 25

When can ionic substances conduct electricity?

Answer 25

melted or dissolved

Question 26

Why do ionic substances conduct electricity when melted or dissolved?

Answer 26

ions are free to move and carry charge

Question 27

Describe the structure of a pure metal

Answer 27

layers of positive metals ions surrounded by delocalised electrons

Question 28

Describe the bonding of a pure metal

Answer 28

strong electrostatic forces of attraction between metal ions and delocalised electrons

Question 29

What are the 4 properties of pure metals

Answer 29

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

Question 30

Explain why pure metals are malleable

Answer 30

layers can slide over each other

Question 31

Explain why metals have high melting/boiling points

Answer 31

electrostatic forces of attraction between positive metal ions and delocalised electrons is strong and requires a lot of energy to break

Question 32

Why are metals good conductors of electricity and thermal energy

Answer 32

delocalised electrons are free to move through the metal

Question 33

What is an alloy

Answer 33

mixture of a metal with atoms of another element

Question 34

explain why alloys are harder than pure metals

Answer 34

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

Question 35

How big are nanoparticles

Answer 35

1-100 nm

Question 36

How are nanomaterials different from bulk materials

Answer 36

nanomaterials have a much higher surface area-to-volume ratio

Question 37

What is the relationship between side length and surface area-to-volume ratio?

Answer 37

as side length decreases by a factor of ten, the surface area-to-volume ratio increases by a factor of ten

Question 38

What are nanoparticles used for

Answer 38

used in healthcare, electronics, cosmetics and catalysts