2.1 Bonding, Structure and Properties

Question 1

Properties of metals (5)

Answer 1

• malleable and ductile
• conduct electricity
• conduct heat
• high melting and boiling points
• react with oxygen to form basic oxides (reactivity varies)

Question 2

Structure of metallic bonding

Answer 2

Electrons from outer shells of atoms are delocalised- free to move throughout the structure

Question 3

Why are there strong metallic bonds in metals and what makes them so strong

Answer 3

Positive ions share delocalised electrons
The bond is strong because of strong electrostatic forces between positive metal ions + and negative electrons -

Question 4

Explain the electrical conductivity of metals

Answer 4

Delocalised electrons carry electrical charge throughout the structure

Question 5

Explain the thermal conductivity of metals

Answer 5

Delocalised electrons and closely packed ions transfer energy throughout the structure by conduction
Free electrons move faster and conduct heat, also vibration of particles

Question 6

Why are metals malleable and ductile

Answer 6

Layers of metal ions can slide past each other when hammered/stretched

Question 7

Why do metals have high melting and boiling points

Answer 7

Large amounts of energy are needed to break the strong metallic bonds

Question 8

What happens to the melting and boiling points of metals as you move across a period and why

Answer 8

Increase
There are more delocalised electrons, increasing the (electrostatic forces &) attraction between the + ions and - free electrons (stronger bonds)

Question 9

What is an ion

Answer 9

A charged particle

Question 10

Giant ionic structure definition

Answer 10

Positive and negative ions held together by strong electrostatic forces in a regular 3D lattice
Each + ion attracts all the - ions around it

Question 11

Why do giant ionic structures have high melting and boiling points

Answer 11

Due to strength of electrostatic forces between the ions

Question 12

When do giant ionic structures only conduct electricity and why

Answer 12

Only when dissolved or molten
Only them are the ions free to move to carry the charge

Question 13

Why are giant ionic compounds brittle

Answer 13

Ion layers are shifted and jump over each other
Ions of the same charge are brought side by side and repel each other

Question 14

Properties of giant ionic structures

Answer 14

High melting and boiling points
Conduct electricity when dissolved or molten

Question 15

What are simple molecular/covalent structures and examples

Answer 15

A few atoms held together by covalent bonds
H, H20, CO2

Question 16

Properties of simple covalent/molecular structures

Answer 16

Low melting and boiling points
Do not conduct electricity

Question 17

Explain why simple covalent structures have low melting and boiling points

Answer 17

Due to weak inter molecular forces (forces between molecules)

Question 18

Explain why simple molecular/covalent structures don’t conduct electricity

Answer 18

No free electrons to carry electric current

Question 19

Arrangement of giant covalent structures

Answer 19

Lots of atoms held together by covalent bonds into giant lattices

Question 20

Why are giant covalent structures extremely strong

Answer 20

Because of the large number of covalent bonds in the structure

Question 21

2 examples of giant covalent structures- allotropes of carbon- bonding structure (each carbon atom bonded to __others)

Answer 21

Diamond 💎- each carbon atom bonded to 4 others
Graphite ✏️ - each carbon atom bonded to 3 others

Question 22

Allotrope definition

Answer 22

A different form of the same element with a different structure

Question 23

Properties of diamond 💎

Answer 23

Does not conduct electricity (no free electrons)
Very strong as very strong bonds

Question 24

Uses of diamond 💎

Answer 24

Drill bits
Glass cutting
Jewellery

Question 25

Property of graphite

Answer 25

Conducts electricity - delocalised electrons between layers carry charge

Question 26

Uses of graphite

Answer 26

Used in pencils ✏️ and lubricants - layers can Slide Over each other.

Question 27

Single bond - how many electrons shared

Answer 27

1 pair

Question 28

Double bond - how many electrons shared

Answer 28

2 pairs shared

Question 29

Carbon nanotubes, fullerenes and graphemes are all what

Answer 29

Allotropes of carbon

Question 30

What are carbon nanotubes

Answer 30

Types of fullerene Graphite layers form and then roll up into tubes

Question 31

Why are carbon nanotubes so strong

Answer 31

Because of the covalently bonded hexagonal sheets

Question 32

Why do carbon nanotubes conduct electricity

Answer 32

Because of the free electrons

Question 33

Uses of carbon nanotubes

Answer 33

Strength: boats, resins, bike components Proposed uses: in miniature electronic circuits

Question 34

Properties of other fullerenes (balls or cages) and uses

Answer 34

Very strong Used to trap molecules- carrying drugs through the body

Question 35

Graphene - what is it and properties

Answer 35

One layer of graphite Thinnest yet strongest material discovered Best conductor of heat/electricity

Question 36

Do individual atoms have the same properties as their bulk form Why? What is another example of this

Answer 36

No! Because of the arrangements of the atoms (different arrangements =different properties) Nano particles

Question 37

Nano scale silver particles uses

Answer 37

Used to kill micro organisms- antiseptic uses

Question 38

Titanium dioxide uses

Answer 38

Blocks UV light -used in transparent sunscreen (advantages) used in cosmetics

Question 39

Possible risks of using nano particles

Answer 39

Damaging to the environment (silver and titanium dioxide Can be absorbed through the skin We don’t know their full effects yet

Question 40

What do smart materials do

Answer 40

Change reversibly with a change in their surroundings

Question 41

Thermochromic pigments-what did they do and uses

Answer 41

Change colour with temperature Mugs, battery power indicators

Question 42

Photochromic pigments what do they do and uses?

Answer 42

Change colour with light intensity Photochromic lenses in sunglasses

Question 43

Shape memory polymers what do they do and uses

Answer 43

Plastics that regain their shape when heated Car bodies- repair dents medical stitches

Question 44

Shape memory alloys what do they do and uses

Answer 44

Metal alloys that regain their shape when heated Deformable glasses frames 👓 Thermostats Surgical wires/plates

Question 45

Hydrogels What do they do and uses?

Answer 45

Shells that absorbable expel water swell or shrink due to temperature or pH changes Nappies, firefighting