Structures

Question 1

Give four properties of giant Ionic lattices

Answer 1

• soluble in water
• high melting point
• conducts electricity when liquid
• crystalline

Question 2

Give two examples of giant Ionic lattices

Answer 2

Sodium chloride

Magnesium oxide

Question 3

Give four properties of simple Covalent / Covalent molecular structures

Answer 3

• low melting and boiling points (tend to be mainly gases)
• not soluble in water
• do not conduct electricity
• soft when solid

Question 4

Give two examples of simple covalent / covalent molecular structures

Answer 4

Iodine and carbon dioxide

Question 5

Give three properties of giant covalent structures

Answer 5

• Very high melting and boiling point
• Diamond does not conduct electricity, graphite and graphene do
• insoluble in water

Question 6

Give a property of Graphite

Answer 6

Slippery soft solid

Question 7

Give a property of graphene

Answer 7

100 times stronger than steel but is very thin, light and inexpensive

Question 8

Draw diamond

Answer 8

-

Question 9

Draw Graphite

Answer 9

-

Question 10

Draw and label Graphene

Answer 10

-

Question 11

Give four properties of a giant metallic structure

Answer 11

High mpt/bpt
Conducts heat and electricity
Ductile (can be stretched into wires)
Malleable (bends)

Question 12

List three main properties of Ionic compounds

Answer 12

• crystalline
• high melting point
• conducts electricity when liquid

Question 13

Sodium chloride conducts electricity when molten but not when solid, explain why?

Answer 13

The electrons have become delocalised and the ions are free to move and therefore carry charge

Question 14

Why do ionic compounds have high melting and boiling points ?

Answer 14

Due to the strong electrostatic forces of attraction between oppositely charged ions which require a lot of energy to break

Question 15

Why can’t some substances conduct electricity as a solid?

Answer 15

The ions are in a fixed position

Question 16

Why do simple covalent structures/molecular covalent structures have low melting/boiling points?

Answer 16

Due to the weak forces of attraction between the molecules (van der Waals) despite that there are strong covalent bonds between the atoms in the molecule

Question 17

Why does diamond not conduct electricity?

Answer 17

It has 4 carbon atoms surrounding each carbon atom and therefore has no free electrons

Question 18

Why does Graphite conduct electricity?

Answer 18

It has a free electron which can carry charge

Question 19

Why is Graphite slippery?

Answer 19

It is in forms of layers which can slide over each other due to weak van der Waals

Question 20

Why do some metallic structures have high melting points and boiling points?

Answer 20

Strong metallic bonds require a lot of energy to break

Question 21

Why do metallic structures conduct heat/electricity?

Answer 21

They have delocalised electrons which have a lot of kinetic energy to move and carry the charge/energy

Question 22

Why are metallic structures malleable?

Answer 22

The sea of electrons allows the layers of ions to slide over each other without disrupting the bonding when a force is applied

Question 23

How many atoms of carbon surround each carbon atom in Graphite?

Answer 23

3

Question 24

Why do diamond and Graphite both habe high melting points?

Answer 24

They have strong covalent bonds in all directions which require a lot of energy to break

Question 25

Which of graphite’s properties means that it can be used as a lubricant ?

Answer 25

It’s weak van der Waals enable layers to slide over one another

Question 26

Why is it that Graphite can conduct electricity?

Answer 26

Carbon is covalently bonded to three carbon atoms. This leaves one free electron per atom to carry current

Question 27

Lead is malleable because (2)

Answer 27

• The result of tightly packed atoms cause the outer electrons to delocalised
• and allow the layers of ions to slide over one another without disrupting the bonding

Question 28

Why can metals produce wire shapes?

Answer 28

They are ductile and have delocalised electrons which allow ions to slide over each other

Question 29

Define alloy

Answer 29

A mixture of two or more elements at least one of which is a metal, and the resulting mixture has metallic properties

Question 30

What is meant by the term ductile ?

Answer 30

Can be stretched into wires

Question 31

Explain fully how a single covalent bond forms

Answer 31

Shared pair of electrons

Question 32

Explain why metals conduct electricity

Answer 32

The electrons have become delocalised and the ions are free to move and therefore carry a charge

Question 33

Describe the bonding and structure in a typical metal like sodium. Use a labelled diagram

Answer 33

(Metal ions and free electrons from outer shells of metal atoms)
The bonding in metals is metallic and it gives a giant metallic lattice. The metallic bond is the attraction between regularly arranged positive metal ions and delocalised electrons

Question 34

Why does HCL have a low boiling point?

Answer 34

Weak van der Waals forces between the molecules, meaning there is little energy required to break the bonds

Question 35

Show the equation for working out the % of gold in an alloy

Answer 35

Number of carats divided by 24 x 100

Question 35

Use of diamond

Answer 35

• Cutting of tools

Question 35

Draw a diagram of an alloy

Answer 35

• Positive Ions
• Different sized ions
• Negative delocalised electrons

Question 36

Give an example of an alloy

Answer 36

• Steel is an alloy of iron and carbon

Question 37

Why are alloys harder than metals (2)

Answer 37

• The different sizes of atoms in an alloy distort the layers in the metallic structure
• Making it more difficult for the layers of ions to slide over each other

Question 38

What is gold used in jewellery usually an alloy of ?

Answer 38

• An alloy with silver, copper and zinc

Question 39

Uses of Graphene

Answer 39

• Batteries

- Solar cells