OCR A Level Chemistry

Topic Questions

A LevelChemistryOCRTopic Questions3. Periodic Table & Energy3.1 Periodicity

3.1 Periodicity

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1a2 marks

The electron configuration of an element is shown below.

1s2 2s2 2p6 3s2  3p6  3d10 4s2  4p6  5s1 4d10

i)
State which block of the periodic table the element is in.
[1] 

ii)
State how many electrons it has in its outer shell.

[1]

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1b1 mark

The periodic table and its elements are arranged in an order.

State what factor determines the order of elements in the periodic table.

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1c1 mark

The periodic table is divided into blocks. State why bromine, phosphorus, and nitrogen are all classified as p-block elements.

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1d2 marks

State the meaning of the term ‘periodicity’.

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2a2 marks

This question is about the periodicity of period 3 elements.

i)
State the trend in melting point in period 3 from sodium to aluminium.

[1] 

ii)
Sodium to aluminium in period 3 all contain metallic bonding. Define the term ‘metallic bonding’.

[1]

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2b1 mark

State the element in Period 3 that has the highest melting point.

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2c3 marks

First ionisation energies is another trend in periodicity that is shown by period 3 elements.

i)
Define first ionisation energy.
[2] 
ii)
State the general trend in first ionisation energies across period 3.

[1]

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2d1 mark

State the element in Period 3 that has the highest first ionisation energy.

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3a2 marks

Silicon has the highest melting point out of all period 3 elements.

Describe the structure and bonding present in silicon.

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3b1 mark

Explain why the melting point of sulfur (S8) is greater than that of phosphorus (P4).

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3c3 marks

Explain why the melting point of aluminium is higher than the melting point of sodium.

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3d3 marks

Explain why aluminium does not follow the general trend in first ionisation energies across the period.

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4a1 mark

Copper is a metal with a high melting point.

State the block of the periodic table that contains copper.

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4b2 marks

Explain, in terms of its structure and bonding, why copper has a high melting point.

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4c2 marks

Draw a labelled diagram to show the arrangement of particles in a crystal of copper.

In your answer, include at least six particles of each type.

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4d1 mark

Describe a similarity in terms of structure between copper and graphite.

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5a1 mark

Element Z has the following first six ionisation energies in kJ mol-1. These are shown below in Table 1.

Table 1

 

1st 

2nd

3rd

4th

5th

6th

Ionisation energy (kJ mol-1)

577

1820

9700

11 600

14 800

18 400

State which group of the periodic table this element belongs to.

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5b2 marks

This question is about the trends in periodicity across period 2.

i)
State which element in period 2 will have the highest first ionisation energy value.
[1] 
ii)
State which element in period 2 will have the highest melting point.

[1]

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5c2 marks

Using your answer from part (b), state and explain using your knowledge of structure and bonding, why carbon has the highest melting point in period 2.

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1a4 marks

This question is about the elements in the first four periods of the Periodic Table.

pt

Explain why an oxygen atom is smaller than a nitrogen atom. 

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1b4 marks

Describe and explain the general trend in first ionisiation energies across Period 3 from Na- Ar. 

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1c1 mark

Write an equation, including state symbols, to represent the fourth ionisation energy of nitrogen. 

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1d3 marks

The successive ionisation energies for another element, J, are shown in Table 1. 

Table 1

Energy number

1st

2nd

3rd

4th

5th

Ionisation energy value / kJ mol−1 

738

1450

7733

10543

13630

i)
State the formula of the compound when element J reacts with chlorine.


[1]

ii)
Explain why the third ionisation energy of element J is larger than the second ionisation energy.

[2]

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2a5 marks

This question is about the properties and trends of properties of different substances.

Graphite is an allotrope of carbon. 

Table 1 shows some properties of graphite. 

Table 1

Hardness Soft
Melting point Very high
Electrical conductivity Good conductor

i)
Describe the bonding and structure in graphite.

[2]

ii)
Explain the properties of graphite, shown in the table, in terms of its bonding and structure. 

[3]

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2b6 marks

Table 2 shows the general trend in melting points across Period 3. 

Table 2

Element

Na

Mg

Al

Si

P4

S8

Cl2

Ar

Melting point / K

371

923

933

1680

317

392

172

84

i)
Explain why silicon has the highest melting point in Period 3. 
[3]
ii)
Explain why sulfur has a higher melting point than phosphorus. 
[3]

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2c2 marks

Sketch graphs can be used to show trends across a period.

i)
Draw a sketch graph to show the general trend in atomic radius across Period 3. 

[1]

3-1_q2c-ocr-a-as--a-level-hard-sq

ii)
Draw a sketch graph to show the general trend in ionisation energy across Period 3. 

[1]

3-1_q2c2-ocr-a-as--a-level-hard-sq

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2d5 marks

There are two elements which deviate from the general trend in first ionisation energy across period 3.

i)
Name these two elements
[1]
ii)
For each one, explain why this deviation occurs.
[4]

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3a10 marks

The bonding and structure of a substance can explain its physical properties. 

The table shows properties of some elements in Period 2 of the Periodic Table. 

Element Li

C (graphite)

 O
Electrical conductivity of solid  Good Good Poor
 Boiling point ( oC) 1342 4000 -183

Explain these properties in terms of bonding and structure. 

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3b6 marks

The melting points of Period 2 elements are shown in the table.

Element

Li

Be

B

C(diamond)

N

O

F

Ne

Melting point / K

454

1551

2573

3970

63

55

53

23

Explain the trend in melting point temperatures across the elements of Period 2 in terms of their structure and bonding.

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4a5 marks

This question is about magnesium.

Magnesium has a second ionisation energy of 1451 kJ mol-1

i)
Write an equation to represent the second ionisation energy of magnesium. 
Include state symbols.
[2]
ii)
Explain why strontium has a lower second ionisation energy than magnesium
[3]

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4b4 marks

Magnesium has a melting point of 650 oC.

i)
Describe the bonding and structure in magnesium. 

ii)
Explain why magnesium has a higher melting point than sodium. 

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4c3 marks

Magnesium is located in Group 2 of the periodic table. 

i)
Give the full electron configuration of the Mg2+ ion.
[1]
ii)
Suggest whether the Mg2+ or Na+ ion has a smaller ionic radius.
 
Give a reason for your answer. 
[2]

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4d2 marks

Magnesium has 12 successive ionisation energies. 

On the graph below, add crosses to show the 12 successive ionisation energies of magnesium. The value for the first ionisation energy is already done. 

You do not need to join the crosses. 

plottng-i-e-data-for-magnesium

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5a3 marks

This question is about the elements in the Periodic Table.

The early Periodic Table arranged elements in order of increasing atomic mass. 

i)
Which two elements from the first twenty elements of the modern Periodic Table are not arranged in order of increasing atomic mass?

[1]

ii)
Why does the modern Periodic Table not arrange some elements, like these, in order of increasing atomic mass?

[1]

iii)
What is the name of the term used to describe the repeating patterns in the Periodic Table?
[1]

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5b5 marks

Figure 1  shows the elements from the first three periods of the Periodic Table.

Figure 1

first-three-periods-of-pt

Identify an element that fits each of the following descriptions:

i)
An element that forms a 2- ion with the same electronic configuration as Ne 
[1]
ii)
The Period 3 element with the highest boiling point 
[1]
iii)
The element from the first three periods with the largest atomic radius 
[1]
iv)
The element from the first three periods with the highest first ionisation energy
[1]
v)
The Period 3 element with the successive ionisation energies shown below: 

Ionisation number

1st

2nd

3rd

4th

Ionisation energy/kJ mol−1

738

1451

7733

10541
[1]

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5c5 marks

Figure 2 shows the first ionisation energies for six consecutive elements labelled A-F. 

Figure 2

ionisation-energy-graph-

i)
Complete the graph to show the first ionisation energies of elements G-K. 

ii)
Explain why the value of the first ionisation energy for D is greater than for C.

How did you do?

5d4 marks

Diamond is made from the element, carbon.

It has the following properties:

   High melting point

   Poor electrical conductivity

   Hard

Explain these properties of diamond, referring to its structure and bonding.

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1a4 marks

The Periodic Table displays the chemical elements, arranged in order of increasing atomic number.  It is made up of groups and periods of elements. 

State and explain the general trend in first ionisation energy across period 2 of the Periodic Table.

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1b3 marks

The general trend in first ionisation energies stated in part (a) is seen across Period 2 of the Periodic Table. However, boron and one other Period 2 element deviate from this trend.  

Identify this element and explain why it deviates from the general trend. 

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1c2 marks

State why nitrogen is classed as a p block element and give its full electron configuration. 

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1d3 marks

Identify the Period 3 element that has the lowest melting point.

Explain your answer with reference to bonding and structure.

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2a3 marks

All elements have a value for a first ionisation energy. The first ionisation energy for all the elements is found in chemistry data books

i)
Define the term first ionisation energy of an element.

ii)
Write the equation for the first ionisation energy of aluminium.

How did you do?

2b2 marks

The table below shows successive ionisation energies of an element A, found in Period 3 of the Periodic Table.

Table 1

Number of electrons

1

2

3

4

5

6

7

8

Ionisation Energy (kJ mol-1)

1012

1904

2914

4964

6274

21268

25431

29872

Identify element A.

Explain your answer using data from Table 1.

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2c6 marks

The graph below in Figure 1 shows some information on the elements of Period 3 of the Periodic Table.

period-3-ionisation-energies

State and explain the trend that this graph shows, including why there are values that deviate from the trend.

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2d1 mark

Explain why the second ionisation energy of aluminium is a larger value than the first ionisation energy.

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3a3 marks

The table below shows the melting points and atomic radii of the elements in Period 3, Na to Cl.

Element Na Mg Al Si P S Cl
Melting point / °C 98  649 660 1410 44 113 –101
Atomic radius / pm 186  160  143 118 110 102 99

1pm = 1 x 10-12 m

Explain the difference in melting point for the elements Na and Mg.

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3b4 marks

The boiling point of diamond is 3550 ℃, but for carbon dioxide it is -78.5 ℃. Both are covalent substances.

Explain this difference with reference to structure and bonding.

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3c2 marks

Sulfur exists as S8 molecules and chlorine as Cl2 molecules. Use this information to explain the difference in their melting points.

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4a5 marks

Like carbon dioxide, graphite is also a covalent substance, but it is a solid at room temperature. Graphite has a melting point of around 3600 °C.

Describe the structure and bonding of graphite and explain why it has such a high melting point.

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4b4 marks

Graphite is made purely of carbon, a non-metal, yet it conducts electricity. Diamond, which is also made purely of carbon, cannot conduct electricity. 

i)
Explain this difference in electrical conductivity between graphite and diamond.

ii)
Give one other difference in the properties of graphite and diamond.

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4c4 marks

Graphite is soft and used as a lubricant, whereas diamond is hard and used in many cutting tools. Both are giant covalent structures. 

Explain this difference with reference to structure and bonding.

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4d3 marks

Both graphite and lithium are good conductors of electricity and have high boiling points.

Explain these similarities in terms of bonding and structure.

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5a3 marks

Another property which shows a trend across a period of the Periodic Table is first ionisation energy.

empty-ionisation-energy-graph

On the axes above, sketch a graph to show the trend in first ionisation energy across Period 2 of the Periodic Table. 

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5b1 mark

Write an equation for the reaction that occurs when the third ionisation energy of silicon is measured.

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5c2 marks

Explain why the value of the third ionisation energy of silicon is higher than the value of the second ionisation energy of silicon. 

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