Year 12 Atomic structure questions	

	Name:	
________________________	

Class:	
________________________	

Date:	
________________________	

 	
Time:	78 minutes	
Marks:	70 marks	
Comments:		

Q1.
Which element is in the p block of the Periodic Table?
 
A	Technetium	 	
B	Terbium	 	
C	Thallium	 	
D	Thorium	 	
(Total 1 mark)
Q2.
(a)  Give the meaning of the term relative atomic mass.
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(2)
(b)  A sample of nickel was ionised by electron impact in a time of flight (TOF) mass spectrometer to produce Ni+ ions. The relative abundance of each isotope is shown in the table below.
 
m/z	58	60	62	
Relative abundance	19	8	3	
Calculate the relative atomic mass of nickel in the sample.
Give your answer to one decimal place.
Relative atomic mass ______________________________
(2)
(c)  State why the inside of a TOF mass spectrometer is operated under vacuum.
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(1)
(d)  Complete the electron configuration of the 58Ni+ ion.
1s2 ________________________________________________________________
(1)
(e)  Calculate the mass, in kg, of a 58Ni+ ion.
Give your answer to three significant figures.
The Avogadro constant, L = 6.02 × 1023 mol−1
Mass ______________________________ kg
(1)
(f)  A 58Ni+ ion travels down the flight tube of a TOF mass spectrometer with constant kinetic energy.
The flight tube is 1.80 m long and the 58Ni+ ion takes 5.82 × 10−7 s to reach the detector.
 
where KE = kinetic energy (J)
 m = mass (kg)
 v = velocity (m s−1)
 d = length of the flight tube (m)
 t = time (s)
Use your answer to part (e) to calculate the kinetic energy, in J, of the 58Ni+ ion as it travels down the flight tube.
(If you were unable to answer part (e), you should use the value
7.37 × 10−25 kg. This is not the correct answer.)
Give your answer to three significant figures.
Kinetic energy ______________________________ J
(3)
(Total 10 marks)
Q3.
(a)  Complete the electron configuration for the aluminium ion, Al3+
1s2 _______________________________________________________________
(1)
(b)  Write an equation, including state symbols, to represent the process for which the energy change is the second ionisation energy of aluminium.
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(1)
(c)  Explain why the second ionisation energy of aluminium is greater than the first ionisation energy of aluminium.
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(1)
(d)  An element, Z, in Period 2 of the Periodic Table has the successive ionisation energies shown in the table.
 
 	First	Second	Third	Fourth	Fifth	
Ionisation energy / kJ mol–1	1090	2350	4610	6220	37 800	
Choose the correct identity of the Period 2 element Z.
Tick (✓) the correct box.
 
Boron		
Carbon		
Nitrogen		
Silicon		
(1)
(Total 4 marks)
Q4.
(a)  The abundance of each isotope in a time of flight (TOF) mass spectrum of a sample of germanium is shown in the table.
 
m/z	70	72	74	
Abundance (%)	24.4	32.4	43.2	
Give the formula of the ion that will reach the detector first.
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(1)
(b)  Use the data in Table above to calculate the relative atomic mass of this sample of germanium.
Give your answer to one decimal place.
Relative atomic mass = ____________________
(2)
(c)  Explain how the abundance of each isotope is determined in a TOF mass spectrometer.
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(2)
(d)  Calculate the mass, in kg, of one atom of 72Ge
The Avogadro constant = 6.02 × 1023 mol–1.
Give your answer to the appropriate number of significant figures.
Mass = ____________________ kg
(2)
(e)  In a TOF mass spectrometer, the ions are accelerated to the same kinetic energy (KE).
KE = mv2 where m = mass (kg) and v = velocity (m s–1)
v = where d = distance (m) and t = time (s)
A 72Ge+ ion is accelerated to a kinetic energy of 3.98 × 10–16 J as it travels down the flight tube that is 3.00 m long.
Calculate the time taken for the 72Ge+ ion to reach the detector.
Use your answer to part (d) in your calculation.
Time = ____________________ s
(3)
(Total 10 marks)
Q5.
(a)     A sample of sulfur consisting of three isotopes has a relative atomic mass of 32.16. The following table gives the relative abundance of two of these isotopes.
 
Mass number of isotope	32	33	
Relative abundance / %	91.0	1.8	
Use this information to determine the relative abundance and hence the mass number of the third isotope.
Give your answer to the appropriate number of significant figures.

 
 
Mass number = ____________________
(4)
(b)     Describe how ions are formed in a time of flight (TOF) mass spectrometer.
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(2)
(c)     A TOF mass spectrometer can be used to determine the relative molecular mass of molecular substances.
Explain why it is necessary to ionise molecules when measuring their mass in a TOF mass spectrometer.
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(2)
(Total 8 marks)
Q6.
Which of these atoms has the smallest number of neutrons?
 
A	3H		
B	4He		
C	5He		
D	4Li		
(Total 1 mark)
Q7.
A sample of ethanedioic acid was treated with an excess of an unknown alcohol in the presence of a strong acid catalyst. The products of the reaction were separated and analysed in a time of flight (TOF) mass spectrometer. Two peaks were observed at m / z = 104 and 118.
(a)     Identify the species responsible for the two peaks.
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(2)
(b)     Outline how the TOF mass spectrometer is able to separate these two species to give two peaks.
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(4)
(Total 6 marks)
Q8.
Which change requires the largest amount of energy?
A        He+(g)      He2+(g) + e–          
B        Li(g)        Li+(g) + e–             
C        Mg+(g)    Mg2+(g) + e–           
D        N(g)       N+(g) + e–               
(Total 1 mark)
Q9.
(a)    Table 1 shows some data about fundamental particles in an atom.
Table 1	
Particle	proton	neutron	electron	
Mass / g	1.6725 × 10–24	1.6748 × 10–24	0.0009 × 10–24	
(i)      An atom of hydrogen can be represented as 1H
Use data from Table 1 to calculate the mass of this hydrogen atom.
______________________________________________________________
(1)
(ii)     Which one of the following is a fundamental particle that would not be deflected by an electric field?
A     electron
B     neutron
C     proton
Write the correct letter, A, B or C, in the box.
 
(1)
(b)     A naturally occurring sample of the element boron has a relative atomic mass of 10.8.
In this sample, boron exists as two isotopes, 10B and 11B
(i)      Calculate the percentage abundance of 10B in this naturally occurring sample of boron.
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(2)
(ii)     State, in terms of fundamental particles, why the isotopes 10B and 11B have similar chemical reactions.
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(1)
(c)    Complete Table 2 by suggesting a value for the third ionisation energy of boron.
Table 2	
 	First	Second	Third	Fourth	Fifth	
Ionisation energy / kJ mol–1	799	2420	 	25 000	32 800	
(1)
(d)     Write an equation to show the process that occurs when the second ionisation energy of boron is measured. Include state symbols in your equation.
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(1)
(e)     Explain why the second ionisation energy of boron is higher than the first ionisation energy of boron.
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(1)
(Total 8 marks)
Q10.
(a)    State the meaning of the term mass number of an isotope.
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(1)
(b)     Give the symbol of the element that has an isotope with a mass number of 68 and has 38 neutrons in its nucleus.
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(1)
(c)     The following shows a simplified diagram of a mass spectrometer.
 
(i)      State what happens to the sample in the parts labelled P and Q.
P ____________________________________________________________
Q ____________________________________________________________
(2)
(ii)     In a mass spectrometer, the isotopes of an element are separated.
Two measurements for each isotope are recorded on the mass spectrum.
State the two measurements that are recorded for each isotope.
Measurement 1 _________________________________________________
Measurement 2 _________________________________________________
(2)
(d)     A sample of element R contains isotopes with mass numbers of 206, 207 and 208 in a 1:1:2 ratio of abundance.
(i)      Calculate the relative atomic mass of R. Give your answer to one decimal place.
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(3)
(ii)     Identify R.
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(1)
(iii)    All the isotopes of R react in the same way with concentrated nitric acid.
State why isotopes of an element have the same chemical properties.
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(1)
(Total 11 marks)
Q11.
This question is about the first ionisation energies of some elements in the Periodic Table.
(a)     Write an equation, including state symbols, to show the reaction that occurs when the first ionisation energy of lithium is measured.
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(1)
(b)     State and explain the general trend in first ionisation energies for the Period 3 elements aluminium to argon.
Trend _____________________________________________________________
Explanation _________________________________________________________
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(3)
(c)     There is a similar general trend in first ionisation energies for the Period 4 elements gallium to krypton.
State how selenium deviates from this general trend and explain your answer.
How selenium deviates from this trend ____________________________________
Explanation _________________________________________________________
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(3)
(d)     Suggest why the first ionisation energy of krypton is lower than the first ionisation energy of argon.
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(1)
(e)     The table below gives the successive ionisation energies of an element.
 
 	First	Second	Third	Fourth	Fifth	
Ionisation energy / kJ mol–1	590	1150	4940	6480	8120	
						
Deduce the group in the Periodic Table that contains this element.
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(1)
(f)      Identify the element that has a 5+ ion with an electron configuration of
1s2 2s2 2p6 3s2 3p6 3d10
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(1)
(Total 10 marks)

Mark schemes
Q1.
C
[1]
Q2.
(a)  Average/mean mass of 1 atom (of an element)
1/12 mass of one atom of 12C
OR
Average/mean mass of atoms of an element
1/12 mass of one atom of 12C
OR
Average / mean mass of atoms of an element × 12
mass of one atom of 12C
OR
(Average) mass of one mole of atoms
1/12 mass of one mole of 12C
OR
(Weighted) average mass of all the isotopes
1/12 mass of one atom of 12C
OR
Average mass of an atom / all isotopes (compared to C-12) on a scale in which an atom of C-12 has a mass of 12
If moles and atoms mixed, max = 1
Mark top and bottom line independently.
All key terms must be present for each mark.
2
(b)  
1
58.9
1
(c)  To stop the ions produced colliding with air or other particles / so that there are only the ions produced from the sample present
Not just to remove air
1
(d)  (1s2)2s22p63s23p63d84s1
1
(e)  9.63 × 10−26 (kg)
1
(f)  
1
 
1
4.61 × 10−13 (J)
If 7.37 × 10−25 used
 
3.52 × 10−12 (J)
1
[10]
Q3.
(a)  2s22p6
1
(b)  Al+(g) ⟶ Al2+(g) + e(−)
1
(c)  The electron is being removed from a positive ion
Nuclear charge is the same but ion smaller than atom so energy needed to remove electron is greater
1
(d)  Carbon
1
[4]
Q4.
(a)  70Ge+
1
(b)  
1
= 72.4
1
(c)  Ions hit the detector and accept electrons causing current to flow
1
Bigger current = higher abundance of that ion
1
(d)  1.20 × 10−25 (kg)
This answer scores 2 marks
1 mark for 1.20 × 10−22 or 1.196 × 10−25 or 1.196 × 10−22
2
(e)  
Allow consequential marking based on answer to (d)
1
 
1
t = 3.68 × 10−5 (s)
1
[10]
Q5.
(a)     Abundance of third isotope = 100 – 91.0 –1.8 = 7.2%
1
  = 32.16
1
7.2y = 32.16 × 100 – 32 × 91 – 33 × 1.8 = 244.6
1
y = 244.6 / 7.2 = 33.97
y = 34
Answer must be rounded to the nearest integer
1
(b)     (for electrospray ionisation)

A high voltage is applied to a sample in a polar solvent
1
the sample molecule, M, gains a proton forming MH+
1
OR
(for electron impact ionisation)
the sample is bombarded by high energy electrons
1
the sample molecule loses an electron forming M+
1
(c)     Ions, not molecules, will interact with and be accelerated by an electric field
1
Only ions will create a current when hitting the detector
1
[8]
Q6.
D
[1]
Q7.
(a)     [CH3OCOCOOH]+
Allow names
1
[CH3OCOCOOCH3]+
Do not allow molecular formula
1
(b)     Positive ions are accelerated by an electric field
1
To a constant kinetic energy
1
The positive ions with m / z of 104 have the same kinetic energy as those with m / z of 118 and move faster
1
Therefore, ions with m / z of 104 arrive at the detector first
1
[6]
Q8.
A
[1]
Q9.
(a)     (i)      1.6734 × 10−24 (g)
Only.
1.6734 × 10−27 kg
Not 1.67 × 10−24 (g).
1
(ii)     B
1
(b)    (i)       = 10.8
OR ratio 10:11 = 1:4 OR 20:80 etc
Allow idea that there are 5 × 0.2 divisions between 10 and 11.
1
abundance of 10B is 20(%)
OR
 = 10.8
10x + 1100 − 11x = 1080
∴ x = 1100 − 1080 = 20%
Correct answer scores M1 and M2.
1
(ii)     Same number of electrons (in outer shell or orbital)
Ignore electrons determine chemical properties.
Same electronic configuration / arrangement
Ignore protons unless wrong.
1
(c)     Range between 3500 and 10 000 kJ mol−1
1
(d)     B+(g)  B2+(g) + e(−)
B+(g) − e(−)  B2+(g)
B+(g) + e(−)  B2+(g) + 2e(−)
Ignore state symbol on electron even if wrong.
1
(e)     Electron being removed from a positive ion (therefore needs more energy) / electron being removed is closer to the nucleus
Must imply removal of an electron.
Allow electron removed from a + particle / species or from a 2+ ion.
Not electron removed from a higher / lower energy level / shell.
Not electron removed from a higher energy sub-level / orbital.
Ignore electron removed from a lower energy sub-level / orbital.
Ignore ‘more protons than electrons’.
Not ‘greater nuclear charge’.
Ignore ‘greater effective nuclear charge’.
Ignore shielding.
1
[8]
Q10.
(a)    (Total number of) protons and neutrons (in nucleus of atom)
(number of) nucleons
1
(b)     Zn
Do not allow Zn−1 or Zn+1 or ZN
Ignore numbers
1
(c)    (i)      P = ionise (sample)
Allow removing an electron / forms (+) ions
1
Q = accelerate (sample)
Allow speeds (ions) up
Penalise molecules / atoms
1
(ii)     m / z
Allow mass / charge
1
(relative) abundance / (relative) intensity
QoL
Allow M1 + M2 in any order
1
(d)    (i)       
M1 = topline
1
M2 = ÷ 4
1
= 207.3
Only
207.3 = 3 marks
1
(ii)     Lead / Pb
Not PB
1
(iii)    Same number of electrons (in outer shell) / same electronic configuration
Ignore electrons determine chemical properties
Ignore reference to p and n if correct
Penalise if incorrect
1
[11]
Q11.
(a)     Li(g) → Li+(g) + e-(g)
Li(g) - e-(g) → Li+(g)
Li(g) + e-(g) → Li+(g) + 2e-
One mark for balanced equation with state symbols
Charge and state on electron need not be shown
1
(b)     Increases
If trend wrong then CE = 0/3 for (b). If blank mark on.
1
Increasing nuclear charge / increasing no of protons
Ignore effective with regard to nuclear charge
1
Same or similar shielding / same no of shells / electron
(taken) from same (sub)shell / electron closer to the
nucleus / smaller atomic radius
1
(c)     Lower
If not lower then CE = 0/3
1
Paired electrons in a (4) p orbital
If incorrect p orbital then M2 = 0
1
(Paired electrons) repel
If shared pair of electrons M2 + M3 = 0
1
(d)     Kr is a bigger atom / has more shells / more shielding
in Kr / electron removed further from nucleus/ electron
removed from a higher (principal or main) energy level
CE if molecule mentioned
Must be comparative answer
QWC
1
(e)     2 / two / II
1
(f)      Arsenic / As
1
[10]