5 Electrons and bonding
OCR Chemistry A Exam-style questions
1 An atom of sulfur contains 16 electrons. These electrons are arranged in shells,
sub-shells, and orbitals.
a i Complete the electron configuration for an atom of sulfur:
1s2 (1 mark)
ii An atom of sulfur has 6 electrons in the third, outer shell. What is the
maximum number of electrons that can be held in the third shell?
(1 mark)
b The electrons in sulfur are arranged into orbitals called s-orbitals and
p-orbitals.
i Define orbital.
(1 mark)
ii Describe the shape of an s-orbital.
(1 mark)
iii Draw the shape of a p-orbital.
(1 mark)
2 Krypton is a noble gas found in Group 18 (0) of the Periodic Table.
a i Complete the full electron configuration of a krypton atom:
Kr: 1s2 (1 mark)
ii Krypton is found in Period 4 of the Periodic Table. Explain how the
electron configuration confirms this.
(1 mark)
, 5 Electrons and bonding
OCR Chemistry A Exam-style questions
iii Identify which Group 2 metal ion will have the same electron configuration
as an atom of krypton.
(1 mark)
b Krypton was once thought to be completely unreactive, but in 1963 a
compound of krypton was made. This compound was called krypton
difluoride, KrF2.
i Suggest the oxidation state of Kr in KrF2.
(1 mark)
ii Krypton difluoride is one of the most powerful oxidising agents known.
Explain what the term oxidising agent means in terms of electron transfer.
(1 mark)
3 A recent study has revealed that some mobile phone users are suffering skin
irritations as a result of their handsets containing nickel or copper.
a In which block of the Periodic Table would you find nickel and copper?
(1 mark)
b The electron configuration for nickel is Ar 3d84s2. A student has attempted
the electrons in box representation in Figure 1:
igure 1 Incorrect ‘electrons in box’ representation of nickel
i What property of electrons is represented by the arrows?
(1 mark)
OCR Chemistry A Exam-style questions
1 An atom of sulfur contains 16 electrons. These electrons are arranged in shells,
sub-shells, and orbitals.
a i Complete the electron configuration for an atom of sulfur:
1s2 (1 mark)
ii An atom of sulfur has 6 electrons in the third, outer shell. What is the
maximum number of electrons that can be held in the third shell?
(1 mark)
b The electrons in sulfur are arranged into orbitals called s-orbitals and
p-orbitals.
i Define orbital.
(1 mark)
ii Describe the shape of an s-orbital.
(1 mark)
iii Draw the shape of a p-orbital.
(1 mark)
2 Krypton is a noble gas found in Group 18 (0) of the Periodic Table.
a i Complete the full electron configuration of a krypton atom:
Kr: 1s2 (1 mark)
ii Krypton is found in Period 4 of the Periodic Table. Explain how the
electron configuration confirms this.
(1 mark)
, 5 Electrons and bonding
OCR Chemistry A Exam-style questions
iii Identify which Group 2 metal ion will have the same electron configuration
as an atom of krypton.
(1 mark)
b Krypton was once thought to be completely unreactive, but in 1963 a
compound of krypton was made. This compound was called krypton
difluoride, KrF2.
i Suggest the oxidation state of Kr in KrF2.
(1 mark)
ii Krypton difluoride is one of the most powerful oxidising agents known.
Explain what the term oxidising agent means in terms of electron transfer.
(1 mark)
3 A recent study has revealed that some mobile phone users are suffering skin
irritations as a result of their handsets containing nickel or copper.
a In which block of the Periodic Table would you find nickel and copper?
(1 mark)
b The electron configuration for nickel is Ar 3d84s2. A student has attempted
the electrons in box representation in Figure 1:
igure 1 Incorrect ‘electrons in box’ representation of nickel
i What property of electrons is represented by the arrows?
(1 mark)
