Periodicity (AQA A Level Chemistry)

Exam Questions

3 hours45 questions
1a2 marks

An element has the following electron configuration.

            1s2,2s2,2p6,3s2,3p6,3d10,4s2,4p4

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

ii)
State how many electrons it has in its outer shell.
1b3 marks

Magnesium can be ionised to form a cation, Mg+.

i)
Write the electron configuration of an Mg+ ion.

ii)

Define the term ‘first ionisation energy’ in relation to magnesium.

1c1 mark

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

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

1d1 mark

The periodic table can be divided into blocks.

State why are silicon, carbon, oxygen and chlorine all classified as p-block elements.

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2a1 mark

State the meaning of the term ‘periodicity’.

2b4 marks

This question is about the periodicity of period 3 elements.

i)
State the trend in atomic radius across period 3.

ii)
State the general trend in first ionisation energies across period 3.

iii)
The first ionisation energy of aluminium is lower than magnesium. Write the full electron configurations of aluminium and magnesium.
2c3 marks

This question is about aluminium in period 3.

i)
Using the electron configurations from part (b), explain why the first ionisation energy of aluminium is lower than magnesium.

ii)
Write the equation, including state symbols, for the second ionisation energy of aluminium.
2d2 marks

The melting point is another trend in periodicity that is shown by period 3 elements.

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

ii)

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

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3a1 mark

Electron configurations for atoms of different elements are shown below.

State which electron configuration represents the element with the largest first ionisation energy.

  1. 1s22s2
  2. 1s22s22p4
  3. 1s22s22p6
  4. 1s22s22p63s2
3b1 mark

State which of the following elements has the highest melting point:

  • Silicon
  • Phosphorus
  • Sulfur
  • Chlorine
3c2 marks

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

Describe the structure and bonding present in silicon.

3d1 mark

The melting point strength for some period 3 elements can be shown as:

S6 > P4 > Cl2

State what intermolecular force is responsible for this pattern in melting points.

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4a1 mark

Antimony, Sb, has atomic number 51.

Complete Figure 1 below to show where antimony is found in the periodic table.

Figure 1

Period

Block

 

 

4b1 mark

Identify the element that is in the d block of the periodic table which forms a +3 ion with the following electron configuration.

[Ar] 3d3

4c1 mark

Ionisation energies can provide evidence for electron structure.

Write an equation, including state symbols, for the first ionisation energy of chlorine.

4d2 marks

Chlorine, Cl2, has a higher melting point than argon, Ar in period 3, however they are both simple molecular structures.

State and explain what intermolecular force is responsible for the higher melting point in chlorine.

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5a1 mark

An element Y has the following first six ionisation energies in kJ mol-1. These are show in Table 1.

Table 1

 

1st

2nd

3rd

4th

5th

6th

Ionisation energy (kJ mol-1)

577

1820

2740

11 600

14 800

18 400

 

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

5b3 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.

ii)
State which element in period 2 will have the highest melting point.

iii)
Write an equation, including state symbols, for the third ionisation energy of beryllium.
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.

5d1 mark

State which sequence below from period 3 shows the melting point decreasing from left to right.

  1. Al, Si, P
  2. Si, P, S
  3. P, S, Cl
  4. S, Cl, Ar

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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 a period of the Periodic Table.

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.

1c2 marks

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

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.
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

28972

Identify element A.

Explain your answer using data from Table 1

2c6 marks

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

Figure 1

KrlIE4YK_6

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

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

Properties of elements in the Periodic Table can be predicted based on the element’s position, and various trends in properties are shown across the periods and down the groups of the Periodic Table. 

State and explain the trend in the atomic radii of the elements seen across Period 3.

3b3 marks

Another property which shows a trend across a period of the Periodic Table is the melting point of a substance.

Explain why the melting point of sodium is lower than that of magnesium.

3c2 marks

Explain how sodium conducts electricity.

3d2 marks

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

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4a3 marks

The Periodic Table is constructed in groups and rows of elements, and there are a number of periodic trends which can be seen.

Identify the element, from silicon to chlorine, that has the largest atomic radius.

Explain your answer.

4b3 marks

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

Figure 1

RaEOso5C_7

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

4c1 mark

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

4d2 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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5a2 marks

The atoms of metal elements from the Periodic Table will lose electrons to form positive metal ions. Different ions have different sizes.

State which of Mg2+ and Al3+ is the larger ion. Explain your answer.

 

5b2 marks

The following table shows some successive ionisation energies of an element in Period 3 of the Periodic Table. 

Table 1

Number of electrons removed

1

2

3

4

5

6

7

8

9

10

Ionisation Energy (kJ mol-1)

495

4562

6910

9453

13354

16613

20117

25496

28934

141370


Identify this Period 3 element and state the equation for the final ionisation energy which will take place. 

5c3 marks

Explain how successive ionisation energies demonstrate the existence of electron shells within atoms.

Use Table 1 to fully justify your answer. 

5d3 marks

Give the meaning of the term 'periodicity'.

Include in your answer reference to the atomic radii of the Period 2 and Period 3 elements.

Specific values of atomic radii are not required.

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1a2 marks

Aluminium has 13 successive ionisation energies.

On Figure 1 below, add crosses to show the 13 successive ionisation energies of aluminium. The value for the first ionisation energy is already completed.

You do not have to join the crosses.

Figure 1

pBNQpWOZ_1

1b1 mark

This question is about ionisation energies.

Figure 2 represents log of the first ten successive ionisation energies of an element X plotted against the number of the electron removed.

Figure 2

Jd5Vq6n4_2

State group in the periodic table is element X found.

1c4 marks

Element A has the following first six ionisation energies in kJ mol-1.

577, 1820, 2740, 11 600, 14 800, 18 400

i)
Explain how you know that element A is in group 3 of the periodic table.

ii)

Two elements B and C are in the same period as A, but B is in the group before A and C is in the group after A in the periodic table.
Give approximate first ionisation energies for elements B and C.

iii)
Explain, using ideas of electronic structure, the difference in ionisation energy values of element A compared to elements B and C.
1d4 marks

This question refers to the elements in the first three periods of the Periodic Table.

Select an element from the first three periods that fits each of the following descriptions.

i)
The element with the highest first ionisation energy.

ii)
The element that forms a 1 ion with the same electron configuration as helium.

iii)
An element which forms a compound with hydrogen in which the element has an oxidation number of −4.

iv)
The element in Period 3 which has the successive ionisation energies shown below in Table 1.

Table 1

Ionisation number

1st

2nd

3rd

4th

Ionisation energy/ kJ mol−1

738

1451

7733

10541

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2a2 marks

Figure 1 below shows the successive ionisation energies for a period 2 element.

Figure 1

Et1u9CMl_3

With reference to electronic structures, state the identity of this element and explain your answer.

2b5 marks

This question is about the elements which have atomic numbers 33 to 37.

The first ionisation energies of these elements are shown in Table 1.

Table 1

Element

As

Se

Br

Kr

Rb

Ionisation energy value kJ /mol-1

947

941

1340

1351

403

i)
Suggest the formulae of the hydrides of arsenic and selenium.

ii)
Explain why the first ionisation energy of rubidium is lower than that of krypton.

iii)
State which of the elements, arsenic to rubidium, has atoms with the smallest atomic radius.
2c6 marks

The trend in melting points across period 3 can be broken down as follows:

Elements 1 to 3: General increase

Elements 4 to 8: General decrease

Explain this trend in melting point across the Period 3 elements.

2d3 marks

This question is about hydrogen, the element with atomic number Z = 1.

Hydrogen can be placed in several different positions in periodic tables. One is immediately above lithium in Group 1. Another is in the centre of the first row, as shown in the AQA Data Sheet.

Evaluate the position of hydrogen when it is placed immediately above lithium and state one reason in favour and two against.

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3a3 marks

This question is about Period 4 of the Periodic Table.

i)
State and explain which of K+ and Ca2+ is the smaller ion.

ii)
Write the electron configuration for a Ca+ ion.
3b4 marks

The first ionisation energies of the elements H to K are shown below in Figure 1.

Figure 1

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State and explain the trend in first ionisation energies shown by the elements with the atomic numbers 2, 10 and 18.

3c6 marks

The melting points of period 2 elements are shown in Table 1 below.

Table 1

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 temperatures across the elements of Period 2 in terms of their structure and bonding.

3d5 marks

Electrons in atoms occupy orbitals.

Figure 2 shows the first ionisation energies for six consecutive elements labelled AF

Figure 2

1RJ7Qr_c_5

i)
Complete the graph of the first ionisation energies for the next five elements.

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

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4a4 marks

The sequence of the first three elements in the Periodic Table is hydrogen, helium and then lithium.

Explain why the first ionisation energy of hydrogen is less than that of helium, but greater than that of lithium.

4b1 mark

Compound J reacts with chlorine. The first five successive ionisation energies for an 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


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

4c3 marks

This question looks at the trends across a period in the periodic table. Four sequences of elements across period 3 are shown below:

Na, Mg, Al                   Al, Si, P                       Si, P, S                                    P, S, Cl

i)
State which sequence shows the melting point increase across period 3?

ii)

Two sequences contain elements that have the same structure in the solid state.
Identify these two sequences and state the structure of each.

4d2 marks

Nitrogen is a period 2 element that exists as a diatomic molecule. The first to third ionisation energies, in kJ mol-1, of nitrogen are 1402, 2856 and 4578.

i)
Write an equation representing the fourth ionisation energy of nitrogen.

ii)
Suggest why the successive ionisation energies of nitrogen increase in value.

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5a3 marks

Table 1 below shows the successive ionisation energies of an unknown element, X

Table 1

Ionisation number

Ionisation energy / kJ mol-1

1st

578

2nd

1817

3rd

2745

4th

11577

5th

14842

6th

18379

Deduce the period and identity of element X and explain your answer with reference to its electron configuration.

5b3 marks

First ionisation energies decrease down groups in the Periodic Table.

Explain this trend and the effect on the reactivity of groups containing metals.

5c4 marks

The ionisation energy values show a general increase across period 4 from gallium to krypton.

i)
State and explain how selenium deviates from this trend.

ii)
Give one other element from period 2 or 3 which also deviates from this general trend, similar to selenium.
5d2 marks

The ionisation energies of sodium, Na, are shown in Table 2 below.

Table 2

Ionisation energy/ kJ mol-1

496

4563

6913

9544

13352

16611

20115

25491

29934

141367

159079

Ionisation number

1st

2nd

3rd

4th

5th

6th

7th

8th

9th

10th

11th

 

 

 

 

 

 

 

 

 

 

 

 

Show with a cross (x), in the third row of the table below, all the ionisation numbers that involve the removal of an electron from an s-orbital.

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