Author: TTW
Last saved by: Marcus Miola

PRACTICE EXAMINATION QUESTIONS FOR 1.1 ATOMIC STRUCTURE
(includes some questions from 1.4 Periodicity)
1.	(a)	Complete the following table.
| Relative mass | Relative charge
Neutron | |
Electron | |
(2)
(b)	An atom has twice as many protons as, and four more neutrons than, an atom of ^9Be. Deduce the symbol, including the mass number, of this atom.
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(2)
 (Total 4 marks)
2.	(a)	Define the terms
(i)	mass number of an atom,
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(ii)	relative molecular mass.
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(3)
(b)	(i)	Complete the electron arrangement for a copper atom.
1s^2 …………………………….........................................................................
(ii)	Identify the block in the Periodic Table to which copper belongs.
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(iii)	Deduce the number of neutrons in one atom of ^65Cu
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(3)

(c)	A sample of copper contains the two isotopes ^63Cu and ^65Cu only. It has a relative atomic mass, A_r, less than 64. The mass spectrum of this sample shows major peaks with m/z values of 63 and 65, respectively.
(i)	Explain why the A_r of this sample is less than 64.
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(ii)	Explain how Cu atoms are converted into Cu^+ ions in a mass spectrometer.
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(iii)	In addition to the major peaks at m/z = 63 and 65, much smaller peaks at m/z = 31.5 and 32.5 are also present in the mass spectrum. Identify the ion responsible for the peak at m/z = 31.5 in the mass spectrum. Explain why your chosen ion has this m/z value and suggest one reason why this peak is very small.
	Identity of the ion .............................................................................................
	Explanation for m/z value ................................................................................
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	Reason why this peak is very small ..................................................................
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(6)
(Total 12 marks) 
3.	A sample of iron from a meteorite was found to contain the isotopes ^54Fe, ^56Fe and ^57Fe. 
(a)	The relative abundances of these isotopes can be determined using a mass spectrometer. In the mass spectrometer, the sample is first vaporised and then ionised.
(i)	State what is meant by the term isotopes.
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(b)	(i)	Define the term relative atomic mass of an element.
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(ii)	The relative abundances of the isotopes in this sample of iron were found to be as follows.
m/z | 54 | 56 | 57
Relative abundance (%) | 5.8 | 91.6 | 2.6

	Use the data above to calculate the relative atomic mass of iron in this sample. Give your answer to one decimal place.
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(4) 
(c)	(i)	Give the electron arrangement of an Fe^2+ ion.
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(ii)	State why iron is placed in the d block of the Periodic Table.
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(iii)	State the difference, if any, in the chemical properties of isotopes of the same element. Explain your answer.
Difference	.........................................................................................................
Explanation	.......................................................................................................
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(4)
(Total 13 marks)
4.	(a)	Complete the following table.
Particle | Relative charge | Relative mass
Proton | |
Neutron | |
Electron | |
(3)
(b)	An atom of element Z has two more protons and two more neutrons than an atom of . Give the symbol, including mass number and atomic number, for this atom of Z.
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(2) 
(c)	Complete the electronic configurations for the sulphur atom, S, and the sulphide ion, S^2–.
S	1s^2 ..............................................................................................................
S^2–	1s^2 ..............................................................................................................
(2)
(d)	State the block in the Periodic Table in which sulphur is placed and explain your answer.
Block ....................................................................................................................
Explanation ..........................................................................................................
(2)
 (Total 9 narks)
5.	(a)	Define the term atomic number of an element.
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(1)
(b)	Give the symbol, including mass number and atomic number, for an atom of an element which contains 12 neutrons and 11 electrons.
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(2)
(c)	In terms of s and p sub-levels, give the electronic configuration of an aluminium atom.
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(1)
(d)	How many neutrons are there in one ^27Al atom?
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(1)
(e)	Define the term relative atomic mass of an element.
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(2)

 (g)	A meteorite was found to contain three isotopes of element X.
A mass spectrometer gave the following information about these isotopes.
m/z | 24.0 | 25.0 | 26.0
Relative abundance | 64.2 | 20.3 | 15.5

(i)	Calculate the relative atomic mass of X.
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(ii)	Using the Periodic Table, suggest the most likely identity of element X.
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(iii)	Suggest one reason why the relative atomic mass of X, given in the Periodic Table, differs from your answer to part (g)(i).
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(5)
(Total 16 marks)

6.	(a)	The diagram in Figure 1 shows the behaviour of the three fundamental particles when passed through an electric field.

Figure 1

(i)	Identify the particles represented by A, B, and C.
A ....................................................... B ............................................................
C .......................................................
(1)

7.	(a)	Define the term atomic number of an atom.
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(1)
(b)	Explain why atoms of the same element may have different mass numbers.
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(1)
(c)	The table below concerns a sample of krypton.
Mass number | 82 | 83 | 84 | 86
Relative abundance | 12 | 12 | 50 | 26

(i)	Name an instrument which is used to measure the relative abundance of isotopes.
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(ii)	Define the term relative atomic mass of an element.
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(iii)	Calculate the relative atomic mass of this sample of krypton.
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(5)
(d)	Explain why the first ionisation energy of rubidium is less than the first ionisation energy of krypton.
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(2)
(Total 9 marks)
9. (c)	The table below shows some data about fundamental particles.
Particle | Proton | neutron | Electron
Mass /g | 1.6725 × 10^–24 | 1.6748 × 10^–24 | 0.0009 × 10^–24
Relative charge | | |
(i)	Complete the table by giving a value for the relative charge of each particle.
(ii)	Calculate the mass of an atom of hydrogen which is made from a proton and an electron.
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(iii)	Calculate the mass of one mole of such hydrogen atoms giving your answer to four decimal places.
(The Avogadro constant, L = 6.0225 × 10^23 mol^–1)
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(iv)	An accurate value for the mass of one mole of hydrogen atoms is 1.0080 g. Give one reason why this value is different from your answer to part (c)(iii).
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(4)

(d)	There is a general trend in the first ionisation energies of the Period 3 elements, Na – Ar
(i)	State and explain this general trend.
Trend .................................................................................................................
Explanation .......................................................................................................
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(ii)	Explain why the first ionisation energy of sulphur is lower than would be predicted from the general trend.
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(5)
(Total 9 marks)

19.	
(a)	(i)	State the general trend in the first ionisation energy of the Period 3 elements from Na to Ar. 
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(ii)	State how, and explain why, the first ionisation energy of aluminium does not follow this general trend. 
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(4)
(b)	Give the equation, including state symbols, for the process which represents the second ionisation energy of aluminium.
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(1)
(Total 5 marks)

20.	There is a general trend in the values of the first ionisation energies of the elements Na to Ar. The first ionisation energies of the elements Al and S deviate from this trend.
(a)	Write an equation, including state symbols, to represent the process for which the energy change is the first ionisation energy of Na.
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(2)

(b)	State and explain the general trend in the values of the first ionisation energies of the elements Na to Ar.
Trend .....................................................................................................................
Explanation ...........................................................................................................
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(3)
(c)	State how, and explain why, the values of the first ionisation energies of the elements Al and S deviate from the general trend.
How the values deviate from the trend .................................................................
Explanation for Al ................................................................................................
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Explanation for S ..................................................................................................
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(5)
(Total 10 marks)

21.	(a)	What is meant by the term first ionisation energy?
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(2)

(b)		The diagram below shows the variation in first ionisation energy across Period 3.

(i)	What is the maximum number of electrons that can be accommodated in an
s sub-level?
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(ii)	What evidence from the diagram supports your answer to part (b(i)?
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(iii)	What evidence from the diagram supports the fact that the 3p sub-level is higher in energy than the 3s?
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(iv)	What evidence from the diagram supports the fact that no more than three unpaired electrons can be accommodated in the 3p sub-level?
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(5)
(Total 7 marks)

22.		Explain why atomic radius decreases across Period 3 from sodium to chlorine.
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(2)
(Total 2 marks)

23.	The diagram below shows the trend in the first ionisation energies of the elements from neon to aluminium.

(a)	Draw crosses on the graph to show the first ionisation energies of silicon, phosphorus and sulphur.
(3)
(b)	Write an equation to illustrate the process which occurs during the first ionisation of neon.
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(1)

(c)	Explain why the first ionisation energy of neon and that of magnesium are both higher than that of sodium.
Explanation for neon ..................................................................................................
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Explanation for magnesium .......................................................................................
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(4)
(d)	Explain why the first ionisation energy of aluminium is lower than that of magnesium.
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(2)
 (Total 10 marks)
24.		Values for the covalent radii of the elements in Period 3 are given in the table below.
Elements | Na | Mg | Al | Si | P | S | Cl | Ar
Covalent radius/nm | 0.157 | 0.136 | 0.125 | 0.117 | 0.110 | 0.104 | 0.099 | ⎯

Explain the decrease in the values shown in the table.
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(Total 3 marks)

Mill Hill High School