1. 1
   A hospital radiographer is explaining how a sodium compound behaves during a medical imaging procedure. Sodium has atomic number 11 and the electronic structure 2,8,1, with electrons occupying shells at increasing distances from the nucleus.

   (a)

   A hospital radiographer is explaining how a sodium-based contrast dye behaves during a medical scan. Sodium has atomic number 11 and an electronic structure of 2,8,1.
   
   How many electrons are in the outer (third) shell of a sodium atom?

   [1 mark]

   • A1
   • B2
   • C8
   • D11

   (b)

   Which statement correctly explains why sodium's electrons are arranged as 2,8,1 rather than, for example, 2,9?

   [1 mark]

   • AElectrons fill the lowest available energy levels (shells) first, and each shell has a maximum number it can hold before the next shell starts filling
   • BElectrons repel each other equally in any shell, so the arrangement is random
   • CElectrons are arranged to match the number of neutrons in the nucleus
   • DElectrons are added to whichever shell is physically largest

   (c)

   Sodium (electronic structure 2,8,1) and chlorine (electronic structure 2,8,7) react together in the contrast dye described above. Explain how you can use their electronic structures to work out how sodium and chlorine atoms will bond together.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   An electrical engineer is investigating why aluminium is used for overhead power cables. Aluminium has atomic number 13 and the electronic structure 2,8,3, meaning its electrons are arranged across three shells around the nucleus.

   (a)

   An electrical engineer is investigating why aluminium (atomic number 13) is used for overhead power cables instead of a non-metal. Aluminium has the electronic structure 2,8,3.
   
   How many electrons does an aluminium atom have in total?

   [1 mark]

   • A3
   • B8
   • C13
   • D23

   (b)

   Which electronic structure correctly represents an aluminium atom, with the shells listed from innermost to outermost?

   [1 mark]

   • A2,3,8
   • B2,8,3
   • C8,2,3
   • D2,8,8

   (c)

   Explain how the position of aluminium in the periodic table can be worked out from its electronic structure, 2,8,3.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A jewellery designer uses argon gas, which is unreactive, to protect molten gold from reacting with the air during casting. Gold has the electronic structure 2,8,18,32,18,1 and argon has the electronic structure 2,8,8.

   (a)

   A jewellery designer is comparing gold (electronic structure 2,8,18,32,18,1) with argon, a noble gas used to protect molten metal from reacting with air during casting (electronic structure 2,8,8). Describe how the electronic structures of these two elements can be represented, using argon as your example, in both number form and as a simple diagram in words.

   [3 marks]

   (b)

   Use electronic structure to explain why argon gas is suitable for protecting the molten gold from reacting with oxygen in the air, and why gold itself is chemically unreactive in this process even though its outer shell is not full.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A textbook author is writing a chapter comparing the electronic structures of the first 20 elements, using magnesium (atomic number 12) and phosphorus (atomic number 15) as worked examples.

   (a)

   Explain how to work out and represent the electronic structure of an atom from its atomic number, using magnesium and phosphorus as examples, and describe what this tells us about the element's position in the periodic table.

   [6 marks]

   (b)

   The textbook author wants to explain why magnesium readily forms an ion by losing electrons, while phosphorus tends to gain electrons when it reacts. Using their electronic structures (magnesium 2,8,2 and phosphorus 2,8,5), explain the ions each element is likely to form and why.

   [6 marks]

   Total for question 4: 12 marks

End of questions