1.5

Question 1

Crystal co-ordination number of Caesium chloride

Answer 1

8:8

Question 2

Crystal co-ordination number of Sodium chloride

Answer 2

6:6

Question 3

Why is CsCl co-ordination number bigger than NaCl

Answer 3

Cs+ is a larger ion so it can accommodate more Cl anions

Question 4

How are ionic crystal structures arranged

Answer 4

Ions are arranged so that the electrostatic attraction between oppositely charged ions is greater than electrostatic repulsion between ions of the same charge

Question 5

Describe the shape of sodium chloride

Answer 5

Cubic lattice

Question 6

Look

Question 7

Caesium chloride shape

Answer 7

Lattice made up of 2 interpenetrating simple cubic structures

Question 8

Look

Question 9

Which ion to show as smaller in diagrams of ionic crystal structures

Answer 9

The cation

Question 10

Physical properties of ionic crystal structures

Answer 10

• high melting temperature
• soluble in water
• hard but brittle
• conducts electricity when liquid but not solid

Question 11

High melting temperature of NaCl

Answer 11

Giant lattices held by strong electrostatic forces between oppositely charged ions which require a lot of energy to overcome

Question 12

Solubility in water of NaCl

Answer 12

As water molecules are polar when in solution the O&- attracted to the cations and the H&+ to the anions
The water molecules pull the ions away form the lattice and the solid dissolves

Question 13

Hard but brittle property of NaCl

Answer 13

When force is applied the layers of ions slide over each other which causes the ions of the same charge to be next to each other which causes the ions to repel each other and the crystal shatters

Question 14

Describe electrical conductivity of NaCl

Answer 14

Solid - poor as the ions are fixed in position by ionic bonds
Liquid - good are the ions are no longer in a lattice and so can move freely and carry a flow of charge = electrical current

Question 15

Describe the structure and bonding in diamond

Answer 15

• tetrahedral structure due to each C atom covalently bonded to 4 others

Question 16

Diamond properties

Answer 16

• high melting temperature
• doesn’t conduct electricity
• very hard
• insoluble in water

Question 17

Look

Question 18

Why does diamond have a very high melting temperature

Answer 18

Strong covalent bonds between atoms

Question 19

Why doesn’t diamond conduct electricity

Answer 19

No free electrons to carry an electrical current

Question 20

Why is diamond so hard

Answer 20

Strong C-C bonds and due to its geometrical rigidity

Question 21

Why is diamond insoluble in water

Answer 21

No ions present to be attracted by polar water molecules

Question 22

Describe structure and bonding in graphite

Answer 22

• layers of hexagonal rings held by van der waals forces
• within the layers each C is covalently bonded to 3 others
• 4th electron from each C atom is delocalised within the layer

Question 23

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Question 24

Properties of graphite

Answer 24

• high melting temperature
• good electricity conductor
• insoluble in water
• soft, slippery feel
• low density

Question 25

Why does graphite have a high melting temperature

Answer 25

There are strong covalent bonds in hexagonal layers

Question 26

Why is graphite a good electricity conductor

Answer 26

Delocalised electron is free to move along the layers so an electrical current can flow Only conducts parallel to it's lines as the electron isn't free to move from one layer to the next

Question 27

Why is graphite insoluble in water

Answer 27

No ions to attract polar water molecules

Question 28

Why does graphite have a soft, slippery feel?

Answer 28

The Van der waals forces between layers are easily broken so the layers can slide over each other May be used as lubricant

Question 29

Why does graphite have a low density

Answer 29

There is a lot of space between layers as the length of the van der waals are longer than the covalent bonded May be used as strong, lightweight sport equipment

Question 30

Structure of iodine

Answer 30

Crystal lattice | Covalent bonds within molecules held together by van der waals forces

Question 31

Properties of iodine

Answer 31

* low melting temperature * poor electrical conductors * normally insoluble in water

Question 32

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Question 33

Why does Iodine have a low melting temperature

Answer 33

Weak van der waals forces between molecules which don't need much energy to break

Question 34

Why is Iodine a poor electrical conductor

Answer 34

Doesn't contain charged particles

Question 35

Why are molecules such as iodine normally insoluble in water

Answer 35

No ions to attract the polar water molecules

Question 36

Describe the structure of ice

Answer 36

* water molecules are arranged in rings of 6 held by hydrogen bonds * each water molecule is hydrogen bonded to 4 others in a tetrahedral coordinated lattice structure * water molecules spread out and it has an open structure and so a lower density than water

Question 37

Properties of ice

Answer 37

* unusually high boiling point | * poor conductors of electricity

Question 38

Why does ice have an unusually high boiling point

Answer 38

Due to presence of hydrogen bonds

Question 39

Why is ice a poor conductor of electricity

Answer 39

Doesn't contain delocalised electrons or ions

Question 40

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Question 41

Describe the structure and bonding of metals

Answer 41

* giant metallic structure * regular arrangement of metal cations (lattice) which is surrounded by a sea of delocalised electrons * strong metallic bond due to electrostatic forces of attraction between nucleus of cations and delocalised electrons * increasing temperature with increased number of delocalised electrons as the attraction is higher - more electrons and stronger cation

Question 42

Properties of metals

Answer 42

* high melting temperature * hard * good thermal conductor * good electrical conductors * malleable and ductile

Question 43

Why do metals have high melting temperatures

Answer 43

Strong forces of attraction

Question 44

Why are metals hard

Answer 44

Strong metallic bonds

Question 45

Why are metals good thermal conductors

Answer 45

Delocalised electrons can pass kinetic energy to each other

Question 46

How are metals good conductors of electricity

Answer 46

Delocalised electrons carry current as when a potential difference is applied across end of a metal Electrons will be attracted and move towards the positive terminal of the cell

Question 47

Why are metals malleable and ductile

Answer 47

When force is applied the layers of cations can slide over each other but as the delocalised electrons move with the cations it prevents the forces of repulsion forming between layers

Question 48

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