Electrons, energy levels and atomic orbitals — Paper 1 · A Level Chemistry 9701

13 In 1999, researchers working in the USA believed that they had made a new element and that it had the following electronic structure. [Rn] 5f146d107s27p6 In which Group of the Periodic Table would you expect to find this element? A II B IV C VI D 0

1 marks

Answer: D

This question in 9701/11 Oct/Nov 2005

3 Gallium nitride, GaN, could revolutionise the design of electric light bulbs because only a small length used as a filament gives excellent light at low cost. Gallium nitride is an ionic compound containing the Ga3+ ion. What is the electron arrangement of the nitrogen ion in gallium nitride? A 1s2 2s2 B 1s2 2s2 2p3 C 1s2 2s2 2p4 D 1s2 2s2 2p6

1 marks

Answer: D

This question in 9701/11 May/June 2006

3 Use of the Data Booklet is relevant to this question. The electronic structures of calcium, krypton, phosphorus and an element X are shown. Which electronic structure is that of element X? A 1s22s22p63s23p3 B 1s22s22p63s23p64s2 C 1s22s22p63s23p63d64s2 D 1s22s22p63s23p63d104s24p6

1 marks

Answer: C

This question in 9701/11 Oct/Nov 2006

2 Use of the Data Booklet is relevant to this question. In forming ionic compounds, elements generally form an ion with the electronic structure of a noble gas. Which ion does not have a noble gas electronic structure? A I– B Rb+ C Sn2+ D Sr2+

1 marks

Answer: C

This question in 9701/11 Oct/Nov 2007

3 In which pair do both atoms have one electron only in an s orbital in their ground states? A Ca, Sc B Cu, Be C H, He D Li, Cr

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Answer: D

This question in 9701/11 Oct/Nov 2008

4 Use of the Data Booklet is relevant to this question. Which graph represents the number of unpaired p orbital electrons for atoms with proton numbers 13 to 18? A B number of number of unpaired unpaired electrons electrons 0 0 13 14 15 16 17 18 13 14 15 16 17 18 proton number proton number C D number of number of unpaired unpaired electrons electrons 0 0 13 14 15 16 17 18 13 14 15 16 17 18 proton number proton number

1 marks

Answer: D

This question in 9701/11 May/June 2009

1 Use of the Data Booklet is relevant to this question. What could be the proton number of an element that has three unpaired electrons in each of its atoms? A 5 B 13 C 15 D 21

1 marks

Answer: C

This question in 9701/11 May/June 2010

19 Two properties of non-metallic elements and their atoms are as follows. property 1 has an oxide that can form a strong acid in water property 2 has no paired 3p electrons Which properties do phosphorus and sulfur have? phosphorus sulfur A 1 and 2 1 only B 1 only 1 and 2 C 1 and 2 1 and 2 D 2 only 1 only

1 marks

Answer: A

This question in 9701/11 May/June 2010

2 Use of the Data Booklet is relevant to this question. What could be the proton number of an element that has three unpaired electrons in each of its atoms? A 5 B 13 C 15 D 21

1 marks

Answer: C

This question in 9701/12 May/June 2010

3 Use of the Data Booklet is relevant to this question. What could be the proton number of an element that has three unpaired electrons in each of its atoms? A 5 B 13 C 15 D 21

1 marks

Answer: C

This question in 9701/13 May/June 2010

2 A simple ion X+ contains eight protons. What is the electronic configuration of X+? A 1s2 2s1 2p6 B 1s2 2s2 2p3 C 1s2 2s2 2p5 D 1s2 2s2 2p7

1 marks

Answer: B

This question in 9701/11 Oct/Nov 2010

1 A simple ion X+ contains eight protons. What is the electronic configuration of X+? A 1s2 2s1 2p6 B 1s2 2s2 2p3 C 1s2 2s2 2p5 D 1s2 2s2 2p7

1 marks

Answer: B

This question in 9701/13 Oct/Nov 2010

22 The formula CH3 can represent an anion, a cation or a free radical. Species with the molecular formula CH3 can act as an electrophile, a free radical or a nucleophile depending on the number of outer shell electrons on the central carbon atom. How many outer shell electrons must be present for CH3 to act in these different ways? CH3 as an CH3 as a CH3 as a electrophile free radical nucleophile A 6 7 8 B 6 8 7 C 7 6 8 D 8 7 6

1 marks

Answer: A

This question in 9701/11 May/June 2011

13 In 1999, researchers working in the USA believed that they had made a new element and that it had the following electronic configuration. [Rn] 5f146d107s27p6 In which Group of the Periodic Table would you expect to find this element? A II B IV C VI D 0

1 marks

Answer: D

This question in 9701/12 May/June 2011

20 The formula CH3 can represent an anion, a cation or a free radical. Species with the molecular formula CH3 can act as an electrophile, a free radical or a nucleophile depending on the number of outer shell electrons on the central carbon atom. How many outer shell electrons must be present for CH3 to act in these different ways? CH3 as an CH3 as a CH3 as a electrophile free radical nucleophile A 6 7 8 B 6 8 7 C 7 6 8 D 8 7 6

1 marks

Answer: A

This question in 9701/13 May/June 2011

3 Which element has an equal number of electron pairs and of unpaired electrons within orbitals of principal quantum number 2? A beryllium B carbon C nitrogen D oxygen

1 marks

Answer: D

This question in 9701/11 Oct/Nov 2011

2 Which element has an equal number of electron pairs and of unpaired electrons within orbitals of principal quantum number 2? A beryllium B carbon C nitrogen D oxygen

1 marks

Answer: D

This question in 9701/13 Oct/Nov 2011

32 Use of the Data Booklet is relevant to this question. In which pairs do both species have the same number of unpaired p electrons? 1 O and Cl + 2 F+ and Ga– 3 P and Ne+

1 marks

Answer: B

This question in 9701/11 May/June 2012

33 Nitrogen and phosphorus are both in Group V of the Periodic Table. Phosphorus forms a chloride with the formula PCl 5. Why is it not possible for nitrogen to form NCl 5? 1 Nitrogen’s outer shell can only contain eight electrons. 2 Nitrogen cannot have oxidation state +5. 3 Nitrogen is almost inert.

1 marks

Answer: D

This question in 9701/11 May/June 2012

31 Nitrogen and phosphorus are both in Group V of the Periodic Table. Phosphorus forms a chloride with the formula PCl 5. Why is it not possible for nitrogen to form NCl 5? 1 Nitrogen’s outer shell can only contain eight electrons. 2 Nitrogen cannot have oxidation state +5. 3 Nitrogen is almost inert.

1 marks

Answer: D

This question in 9701/13 May/June 2012

32 Use of the Data Booklet is relevant to this question. In which pairs do both species have the same number of unpaired p electrons? 1 O and Cl + 2 F+ and Ga– 3 P and Ne+

1 marks

Answer: B

This question in 9701/13 May/June 2012

34 Which statements are correct for all three halogens, chlorine, bromine and iodine? 1 They all form hydrides that are strong acids in aqueous solution. 2 They all react with aqueous sodium hydroxide to form oxo-anions. 3 They all require one more electron to fill the p orbitals of their outer shells.

1 marks

Answer: A

This question in 9701/13 May/June 2012

2 Use of the Data Booklet is relevant to this question. The 68Ge isotope is medically useful because it undergoes a natural radioactive process to give a gallium isotope, 68Ga, which can be used to detect tumours. This transformation of 68Ge occurs when an electron enters the nucleus, changing a proton into a neutron. Which statement about the composition of an atom of the 68Ga isotope is correct? A It has 4 electrons in its outer p subshell. B It has 13 electrons in its outer shell. C It has 37 neutrons. D Its proton number is 32.

1 marks

Answer: C

This question in 9701/11 Oct/Nov 2012

31 Use of the Data Booklet is relevant to this question. Free-radicals play an important part in reactions involving the destruction of the ozone layer and the substitution of alkanes by chlorine. Some free-radicals contain two unpaired electrons. Such species are called diradicals. Which species are diradicals? 1 O 2 Cl 3 CH3

1 marks

Answer: D

This question in 9701/11 May/June 2013

34 The first ionisation energies of twenty successive elements in the Periodic Table are represented in the graph. The letters given are not the normal symbols for these elements. 2500 2000 1500 first ionisation energy / kJ mol _1 1000 500 0 A B C D E F G H I J K L M N O P Q R S T element Which statements about this graph are correct? 1 Elements B, J and R are in Group 0 of the Periodic Table. 2 Atoms of elements D and L contain two electrons in their outer shells. 3 Atoms of elements G and O contain a half-filled p subshell.

1 marks

Answer: A

This question in 9701/11 May/June 2013

31 Use of the Data Booklet is relevant to this question. In which pairs do both species have the same number of unpaired p electrons? 1 Al 2– and O+ 2 N and Cl 2+ 3 C and Cl +

1 marks

Answer: A

This question in 9701/12 May/June 2013

32 Use of the Data Booklet is relevant to this question. Carbon and nitrogen are adjacent in the Periodic Table. Which properties do they both have? 1 There is an empty 2p orbital in one atom of the element. 2 The principal quantum number of the highest occupied orbital is 2. 3 They form compounds in which their atoms form bonds with four other atoms.

1 marks

Answer: C

This question in 9701/11 Oct/Nov 2013

32 Use of the Data Booklet is relevant to this question. Carbon and nitrogen are adjacent in the Periodic Table. Which properties do they both have? 1 There is an empty 2p orbital in one atom of the element. 2 The principal quantum number of the highest occupied orbital is 2. 3 They form compounds in which their atoms form bonds with four other atoms.

1 marks

Answer: C

This question in 9701/12 Oct/Nov 2013

1 Use of the Data Booklet is relevant to this question. Atoms of element X have six unpaired electrons. What could be element X? A carbon B chromium C iron D selenium

1 marks

Answer: B

This question in 9701/11 May/June 2014

31 Use of the Data Booklet is relevant to this question. Which ions contain one or more unpaired electrons? 1 Cu2+ 2 Mn3+ 3 V3+

1 marks

Answer: A

This question in 9701/11 Oct/Nov 2014

2 Four electronic configurations are shown below. Three of these configurations belong to atoms of the elements chlorine, sodium and vanadium. Which electronic configuration belongs to an atom of another element? A 1s22s22p63s1 B 1s22s22p63s23p5 C 1s22s22p63s23p63d34s2 D 1s22s22p63s23p63d64s2

1 marks

Answer: D

This question in 9701/12 May/June 2016

5 Which isolated gaseous atom has a total of five electrons occupying spherically shaped orbitals? A boron B fluorine C sodium D potassium

1 marks

Answer: C

This question in 9701/13 May/June 2016

5 The 68Ge isotope is medically useful because it undergoes a natural radioactive process to give an isotope of a different element, 68X, which can be used to detect tumours. This transformation of 68Ge occurs when an electron enters the nucleus and changes a proton into a neutron. Which statement about the composition of an atom of 68X is correct? A It has 4 electrons in its outer p orbitals. B It has 13 electrons in its outer shell. C It has 37 neutrons. D Its proton number is 32.

1 marks

Answer: C

This question in 9701/11 Oct/Nov 2016

5 The 68Ge isotope is medically useful because it undergoes a natural radioactive process to give an isotope of a different element, 68X, which can be used to detect tumours. This transformation of 68Ge occurs when an electron enters the nucleus and changes a proton into a neutron. Which statement about the composition of an atom of 68X is correct? A It has 4 electrons in its outer p orbitals. B It has 13 electrons in its outer shell. C It has 37 neutrons. D Its proton number is 32.

1 marks

Answer: C

This question in 9701/13 Oct/Nov 2016

31 An isolated gaseous atom of element X has paired electrons in at least one of its 3d orbitals and has a filled 4s subshell. What could be the identity of element X? 1 iron 2 gallium 3 copper

1 marks

Answer: B

This question in 9701/12 May/June 2017

31 Which statements about the atoms 23Na and 24Mg are correct? 1 They have the same number of filled electron orbitals. 2 They have the same number of neutrons. 3 They are both reducing agents.

1 marks

Answer: C

This question in 9701/13 May/June 2017

2 The electronic configuration of the two outermost shells of an atom is 3s23p63d54s2. What is this atom? A manganese B phosphorus C strontium D vanadium

1 marks

Answer: A

This question in 9701/12 Feb/March 2018

1 This question refers to isolated gaseous atoms. In which atom are all electrons paired? A Ba B Br C S D Si

1 marks

Answer: A

This question in 9701/11 May/June 2018

2 The electronic configuration of an atom of sulfur is 1s22s22p63s23p4. How many valence shell and unpaired electrons are present in one sulfur atom? valence shell unpaired electrons electrons A 2 1 B 4 2 C 6 0 D 6 2

1 marks

Answer: D

This question in 9701/12 May/June 2018

3 The table refers to the electron distribution in the second shell of an atom with eight protons. Which row is correct for this atom? orbital shape orbital shape number of number of orbital type orbital type electrons electrons A p 2 s 4 B p 4 s 2 C s 2 p 4 D s 4 p 2

1 marks

Answer: B

This question in 9701/13 May/June 2018

31 Which ions contain one or more unpaired electrons? 1 Cu2+ 2 Mn3+ 3 V3+

1 marks

Answer: A

This question in 9701/11 Oct/Nov 2018

3 Which statement about a 3p orbital is correct? A It can hold a maximum of 6 electrons. B It has the highest energy of the orbitals with principal quantum number 3. C It is at a higher energy level than a 3s orbital but has the same shape. D It is occupied by one electron in an isolated phosphorus atom.

1 marks

Answer: D

This question in 9701/12 Feb/March 2019

32 In which pairs do both species have the same number of unpaired electrons in p orbitals? 1 O and Cl + 2 F+ and Ga– 3 N and Kr3+

1 marks

Answer: A

This question in 9701/12 Feb/March 2019

4 The outermost electron in an atom of neon occupies a particular orbital. Which row shows the relative energy and shape of this orbital? energy of orbital relative shape of orbital to other occupied orbitals A higher or equal B higher or equal C lower or equal D lower or equal

1 marks

Answer: A

This question in 9701/11 May/June 2019

13 The eight elements sodium to argon are in the same period of the Periodic Table. The equation corresponding to the first ionisation energy is shown. X(g) → X+(g) + e– For which of these eight elements is the electron in this equation removed from a filled orbital? A Mg, Al, Si, P, S, Cl and Ar B Al, Si, P, S, Cl and Ar only C Mg, S, Cl and Ar only D S, Cl and Ar only

1 marks

Answer: C

This question in 9701/12 May/June 2019

3 Which atom has exactly three unpaired electrons? A an isolated gaseous aluminium atom B an isolated gaseous carbon atom C an isolated gaseous chromium atom D an isolated gaseous phosphorus atom

1 marks

Answer: D

This question in 9701/13 May/June 2019

4 Which statement about the electrons in a ground state carbon atom is correct? A Electrons are present in four different energy levels. B There are more electrons in p orbitals than there are in s orbitals. C The occupied orbital of highest energy is spherical. D The occupied orbital of lowest energy is spherical.

1 marks

Answer: D

This question in 9701/12 Oct/Nov 2019

36 Nitrogen gas is unreactive, whereas oxygen gas and chlorine gas are reactive. Which statements help to explain this difference? 1 The two N atoms in an N2 molecule are held together by a very strong triple bond. 2 The triple bond between two N atoms is not polar. The bonds in O2 and Cl 2 are polar. 3 The atoms in N2 have a full outer shell of electrons. The atoms in O2 and Cl 2 do not have a full outer shell of electrons.

1 marks

Answer: D

This question in 9701/13 Oct/Nov 2019

31 Carbon and nitrogen are adjacent in the Periodic Table. Which properties do they both have? 1 There is an empty 2p orbital in each atom of the element. 2 The principal quantum number of the highest occupied orbital is 2. 3 They can form compounds in which their atoms form four bonds.

1 marks

Answer: C

This question in 9701/12 Feb/March 2020

3 When considering one molecule of ethene, which row describes both the hybridisation of the atomic orbitals in the carbon atoms and the overall bonding? hybridisation bonding A sp2 4 σ bonds 1 π bond B sp2 5 σ bonds 1 π bond C sp3 4 σ bonds 1 π bond D sp3 5 σ bonds 1 π bond

1 marks

Answer: B

This question in 9701/11 May/June 2020

10 In which pair does each species have the same number of unpaired electrons? A Al and Cu2+ B Ca and Cr3+ C Ca and Ni2+ D Fe3+ and O2–

1 marks

Answer: A

This question in 9701/11 May/June 2020

1 Which particle has equal numbers of protons and neutrons and an electronic structure of 1s22s22p63s23p6? A 39 Ar B 40 20Ca 2 + C 16 8O 2 − D 32 S 18 16

1 marks

Answer: B

This question in 9701/13 May/June 2020

8 What is the electronic configuration of an isolated Ni2+ ion? A 1s22s22p63s23p63d64s2 B 1s22s22p63s23p63d74s1 C 1s22s22p63s23p63d104s2 D 1s22s22p63s23p63d8

1 marks

Answer: D

This question in 9701/13 May/June 2020

14 The electronic arrangement for atoms of four elements is given. Which element is the strongest oxidising agent? A 1s22s22p5 B 1s22s22p63s2 C 1s22s22p63s23p5 D 1s22s22p63s23p64s2

1 marks

Answer: A

This question in 9701/11 Oct/Nov 2020

3 Which atomic orbitals are occupied in an atom of phosphorus? A 1p 2s 2p B 2s 2p 2d C 2s 2p 3s D 2p 3s 3d

1 marks

Answer: C

This question in 9701/12 Oct/Nov 2020

14 The electronic arrangement for atoms of four elements is given. Which element is the strongest oxidising agent? A 1s22s22p5 B 1s22s22p63s2 C 1s22s22p63s23p5 D 1s22s22p63s23p64s2

1 marks

Answer: A

This question in 9701/13 Oct/Nov 2020

2 Where in the Periodic Table is the element that has an outer electron shell arrangement of 4s24p3? Group Period A 13 3 B 13 4 C 15 3 D 15 4

1 marks

Answer: D

This question in 9701/12 Feb/March 2021

2 In which pair of species do both species have only one unpaired p electron? A Ar+ and C– B B and Ti+ C F and Ga D Se– and Si–

1 marks

Answer: C

This question in 9701/11 May/June 2021

4 The ion X2+ has the same electronic configuration as the atom Kr. What is the electronic configuration of an atom of X? A [Ar] 4s23d104p6 B [Ar] 4s23d104p65s2 C [Ar] 4s24d104p6 D [Ar] 4s24d104p65s2

1 marks

Answer: B

This question in 9701/11 Oct/Nov 2021

4 Which atom has more unpaired electrons than paired electrons in orbitals of principal quantum number 2? A carbon B nitrogen C oxygen D fluorine

1 marks

Answer: B

This question in 9701/12 Oct/Nov 2021

4 The ion X2+ has the same electronic configuration as the atom Kr. What is the electronic configuration of an atom of X? A [Ar] 4s23d104p6 B [Ar] 4s23d104p65s2 C [Ar] 4s24d104p6 D [Ar] 4s24d104p65s2

1 marks

Answer: B

This question in 9701/13 Oct/Nov 2021

1 Which atom has its outermost electron in an orbital of the shape shown, with principal quantum number 3? A sodium B chlorine C calcium D bromine

1 marks

Answer: B

This question in 9701/11 May/June 2022

2 This question refers to isolated gaseous atoms in the ground state. In which atom are all electrons paired? A Ba B Br C S D Si

1 marks

Answer: A

This question in 9701/12 May/June 2022

1 Which atom has exactly three unpaired electrons in the ground state? A an isolated gaseous aluminium atom B an isolated gaseous carbon atom C an isolated gaseous chromium atom D an isolated gaseous phosphorus atom

1 marks

Answer: D

This question in 9701/13 May/June 2022

3 Which statement about the electrons in a ground state carbon atom is correct? A Electrons are present in four different energy levels. B There are more electrons in p orbitals than there are in s orbitals. C The occupied orbital of highest energy is spherical. D The occupied orbital of lowest energy is spherical.

1 marks

Answer: D

This question in 9701/11 Oct/Nov 2022

3 Which statement about the electrons in a ground state carbon atom is correct? A Electrons are present in four different energy levels. B There are more electrons in p orbitals than there are in s orbitals. C The occupied orbital of highest energy is spherical. D The occupied orbital of lowest energy is spherical.

1 marks

Answer: D

This question in 9701/13 Oct/Nov 2022

20 HCN has been detected in interstellar gas. The molecules below have also been detected in interstellar gas. Which molecule contains the same total number of valence shell (outer shell) electrons as HCN? A HNO B NH3 C NO D PN

1 marks

Answer: D

This question in 9701/13 May/June 2023

2 The second ionisation energy of oxygen is greater than the second ionisation energy of fluorine. Which factor explains this difference? A The atomic radius of an oxygen atom is smaller than that of fluorine. B The covalent bond in a fluorine molecule is weaker than the bond in an oxygen molecule. C A spin-paired electron is removed from fluorine but not from oxygen. D Fluorine has more electrons in total than oxygen. This causes a greater shielding of the nuclear attraction in fluorine.

1 marks

Answer: C

This question in 9701/12 Oct/Nov 2023

4 This question is about the first ionisation energies of magnesium and neon. Which row is correct? first ionisation type of electron removed energy from Mg from Ne A Mg > Ne p s B Mg > Ne s p C Ne > Mg p s D Ne > Mg s p

1 marks

Answer: D

This question in 9701/13 May/June 2024

2 Compound X contains two elements, Y and Z. Element Y is in Period 2 of the Periodic Table. In one atom of element Y, the p sub-shell has all three orbitals occupied; only one of these three orbitals is fully occupied. Element Z is in Period 3 of the Periodic Table. In one atom of element Z, the p sub-shell has only two orbitals occupied. What is the formula of compound X? A CCl 4 B SiCl 4 C SiO2 D SO2

1 marks

Answer: C

This question in 9701/11 Oct/Nov 2024

2 Compound X contains two elements, Y and Z. Element Y is in Period 2 of the Periodic Table. In one atom of element Y, the p sub-shell has all three orbitals occupied; only one of these three orbitals is fully occupied. Element Z is in Period 3 of the Periodic Table. In one atom of element Z, the p sub-shell has only two orbitals occupied. What is the formula of compound X? A CCl 4 B SiCl 4 C SiO2 D SO2

1 marks

Answer: C

This question in 9701/13 Oct/Nov 2024

4 The first seven ionisation energies of an element between lithium and neon in the Periodic Table are shown. 1310 3390 5320 7450 11000 13300 71000 kJmol–1 What is the outer electronic configuration of the element? A 2s2 B 2s22p1 C 2s22p4 D 2s22p6

1 marks

Answer: C

This question in 9701/11 May/June 2025

14 Which statement about a 3p orbital is correct? A It can hold a maximum of six electrons. B It has the highest energy of the orbitals with principal quantum number 3. C It is at a higher energy level than a 3s orbital but has the same shape. D It is occupied by one electron in an isolated phosphorus atom.

1 marks

Answer: D

This question in 9701/11 May/June 2025

1 Which isolated gaseous atom has a total of five electrons occupying spherically shaped orbitals? A sodium B fluorine C boron D potassium

1 marks

Mark scheme: Question Answer Marks 1 A 1

This question in 9701/13 May/June 2025

9 Which graph represents the number of unpaired electrons in the atoms of six elements in Period 3 of the Periodic Table? A B number of number of unpaired unpaired electrons electrons 0 0 13 14 15 16 17 18 13 14 15 16 17 18 proton number proton number C D number of number of unpaired unpaired electrons electrons 0 0 13 14 15 16 17 18 13 14 15 16 17 18 proton number proton number

1 marks

Answer: D

This question in 9701/14 May/June 2025

1 What is the electrons in boxes notation for the Fe3+ ion? 3d 4s A [Ar] B [Ar] C [Ar] D [Ar]

1 marks

Mark scheme: Question Answer Marks 1 D 1

This question in 9701/12 Oct/Nov 2025

1 What is the electronic configuration for the particle ? A+ 27 13 l A 1s22s22p63s13p1 B 1s22s22p63s2 C 1s22s22p63s23p2 D 1s22s22p63s23p63d74s1

1 marks

Mark scheme: Question Answer Marks 1 B 1

This question in 9701/13 Oct/Nov 2025