Edexcel AS Chemistry

Topic Questions

ASChemistryEdexcelTopic Questions1. Physical Chemistry1.2 Ions & Electrons

1.2 Ions & Electrons

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1a1 mark

This question is about the electronic structure of some Group 5 elements.

Which is the electronic configuration of the arsenide ion, As3–?

  ☐ A 1s22s22p63s23p63d104s2
  ☐ B 1s22s22p63s23p63d104s24p3
  ☐ C 1s22s22p63s23p63d104s24p6
  ☐ D 1s22s22p63s23p63d104s24p34d3

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1b2 marks

The electronic configuration of a phosphorus atom can be written

1s22s22p63s23p3


An alternative way to express the electronic configuration is

q1b-8cho-as-1-nov-2020-qp-edexcel-a-level-chem

i)
State what is meant by the two arrows in the first box.

(1)

ii)
State why the arrows are all pointing in the same direction in the 3p boxes.

(1)

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2a2 marks

This question is about ionisation energies.

i)
Which equation represents the second ionisation of bromine?

(1)

  ☐ A Br(g) + e– → Br–(g)
  ☐ B Br-(g) + e– → Br2–(g)
  ☐ C Br(g) - 2e– → Br2+(g)
  ☐ D Br+(g) - e– → Br2+(g)

ii)
Which set of successive ionisation energies is most likely to be associated with the element boron?
(1)
  ☐ A 738, 1451, 7733, 10541, 13629
  ☐ B 801, 2427, 3660, 25026, 32828
  ☐ C 1086, 2353, 4621,  6223, 37832
  ☐ D 1402, 2856, 4578,  7475,  9445

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2b5 marks
i)
Complete the graph to show how the first ionisation energies of the Period 3 elements change across the period. Precise figures are not required.
(3)
First ionisation energies of the Period 3 elements

q2bi-8cho-as-1-nov-2020-qp-edexcel-a-level-chem
ii)
The successive ionisation energies of sodium are shown on the graph.

q2bii-8cho-as-1-nov-2020-qp-edexcel-a-level-chem
State what deductions can be made from this graph.
(2)

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31 mark

What is the electronic configuration of the sulfide ion, S2−?

  ☐ A 1s22s22p63s23p2
  ☐ B 1s22s22p63p4
  ☐ C 1s22s22p63s23p4
  ☐ D 1s22s22p63s23p6

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1a
Sme Calculator3 marks

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

i)
Hydrogen has two stable isotopes. Complete the table to show the number of subatomic particles present in the nuclei of these two isotopes of hydrogen.
 
Isotope Number of protons Number of neutrons
straight H presubscript 1 presuperscript 1    
   
 
(1)
 
ii)
Use the data in the table to explain the term isotopes.
 (2)

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1b
Sme Calculator3 marks

The relative atomic mass of hydrogen in the Periodic Table is 1.0.

This is correct to two significant figures.

 

The table gives data for the relative isotopic mass and natural abundance of the two stable isotopes of hydrogen.

 
Isotope  Relative isotopic mass Percentage abundance
straight H presubscript 1 presuperscript 1 1.007825 99.9885
begin mathsize 14px style H presubscript 1 presuperscript 2 end style 2.014101 0.0115
 
i)
Using the data in the table, give a reason why it can be estimated that the relative atomic mass of hydrogen is greater than 1.0. 
(1)
 
ii)
Calculate the relative atomic mass of hydrogen from these data, giving your answer to four decimal places.
 
(2)

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1c6 marks
i)
Write an equation to represent the first ionisation energy of hydrogen.
Include state symbols.
 (2)
 
ii)
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.
 (4)

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1d3 marks

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 Periodic Table on the back cover.

 

Criticise the position of hydrogen immediately above lithium by giving one reason in favour and two against. 

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2a8 marks

Sulfur is a bright yellow crystalline solid at room temperature.
Sulfur forms rings of 8 sulfur atoms so the formula of the yellow solid is S8.

A section of a periodic table showing values of first ionisation energy in kJ mol–1 is shown.

q4a-8cho-as-1-oct-2021-edexcel-a-level-chem

i)
Which equation represents the first ionisation energy of sulfur?

(1)
  ☐ A S(s) → S+(g) + e–
  ☐ B S8(s) → straight S subscript 8 superscript plus(g) + e–
  ☐ C S(g) → S+(g) + e–
  ☐ D S8(g) → begin mathsize 14px style S subscript 8 to the power of plus sign end style(g) + e–

ii)

Explain the trend in the values of the first ionisation energies for the group containing sulfur.

(3)

iii)
Explain why the first ionisation energy of sulfur is lower than that of chlorine.

(2)

iv)
Explain why the first ionisation energy of sulfur is lower than that of phosphorus.

(2)

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2b
Sme Calculator5 marks

Compound X is an oxide of sulfur. A gaseous sample of 0.318 g of X occupied a volume of 132 cm3 at a temperature of 420 K and pressure of 105 kPa.

The number of moles of a gas and the volume occupied by it can be found using the ideal gas equation

pV = nRT

Calculate the relative molecular mass of X and hence its molecular formula.
You must show all your working.

[R = 8.31 J mol–1 K–1]

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2c3 marks

Sulfur and the other elements in Group 6 form dihydrogen compounds.

Compound Atomic number of
Group 6 element		 Melting temperature
/ K
H2O 8 273
H2S 16 To be estimated
H2Se 34 207
H2Te 52 224
H2Po 84 238

i)
Plot a graph of atomic number of the Group 6 element on the x-axis against melting temperature of the dihydrogen compound on the y-axis.

(2)

q4ci-8cho-as-1-oct-2021-edexcel-a-level-chem

ii)
Give an estimate of the melting temperature of H2S.

(1)

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3a2 marks

Ionisation energies provide information about the number of electrons and the arrangement of the electrons in an atom of an element.

A student’s definition of first ionisation energy is shown.

First ionisation energy is the energy released when one mole of gaseous atoms loses one mole of electrons to form one mole of gaseous 1+ ions.


There is one incorrect word in the student’s definition.

Identify the word, giving the reason why this word is incorrect.

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3b2 marks

Write an equation for the second ionisation energy of oxygen.
Include state symbols.

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3c3 marks

A sodium atom has 11 protons whereas a potassium atom has 19 protons.

Explain why the first ionisation energy of sodium is greater than that of potassium.

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3d
Sme Calculator7 marks

The successive ionisation energies for magnesium are given in the table.

image-3

i)
Complete the table.

(1)

ii)
Give a reason why the logarithm of the ionisation energy, rather than just the ionisation energy, is used to plot a graph.
(1)

iii)

Give a reason why the successive ionisation energies increase.

(1)

iv)
Plot the graph of log(ionisation energy) against electron number removed.

Join the individual points using straight lines.

(3)

q4civ-9cho-al-1-oct-2021-edexcel-a-level-chem

v)
Identify on the graph, using a circle, the points that represent the removal of the electrons in the outermost energy level of magnesium.

(1)

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3e1 mark

Estimate a value for the first ionisation energy of oxygen given the data in the table.

Element First ionisation energy / kJmol–1
carbon 1086
nitrogen 1402
oxygen  

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