1. 1
   Potassium bromide is formed when potassium, a Group 1 metal, reacts with bromine, a Group 7 non-metal, transferring electrons to form ions.

   (a)

   What charge does the potassium ion formed in this reaction carry?

   [1 mark]

   • A+1
   • B−1
   • C+2
   • D0

   (b)

   What charge does the bromide ion formed in this reaction carry?

   [1 mark]

   • A−2
   • B+1
   • C−1
   • D0

   (c)

   Explain, in terms of electron transfer, why potassium forms a K⁺ ion and bromine forms a Br⁻ ion when they react together.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   A textbook shows several ions written in standard form, including Na⁺ for a sodium ion and Cl⁻ for a chloride ion, and asks students to interpret what this notation represents.

   (a)

   A sodium ion is written in standard form as Na⁺. What does the '+' superscript indicate about this ion?

   [1 mark]

   • AThe sodium atom has gained one electron, so it has one more electron than protons
   • BThe sodium atom has lost one electron, so it has one more proton than electrons
   • CThe sodium atom has gained an extra proton
   • DThe sodium atom has lost a neutron

   (b)

   A chloride ion is correctly written in standard form as which of the following?

   [1 mark]

   • AClO⁻
   • BCl⁺
   • CCl2⁻
   • DCl⁻

   (c)

   Explain what the standard notation Na⁺ and Cl⁻ reveals about the number of electrons gained or lost by each atom.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   Lithium fluoride is formed from lithium, a Group 1 metal, and fluorine, a Group 7 non-metal, when the two elements react together.

   (a)

   State the charge on the lithium ion and on the fluoride ion formed, explaining your reasoning based on their group numbers.

   [3 marks]

   (b)

   Explain in detail the process of electron transfer that occurs when lithium fluoride forms, and explain why both ions end up with the same electron arrangement as a noble gas.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A chemistry teacher compares Group 1 metals, which form ions of charge +1, with Group 7 halogens, which form ions of charge −1, when reacting with elements from the other group.

   (a)

   Explain why Group 1 metals form ions with a charge of +1, and why Group 7 non-metals form ions with a charge of −1, referring to the electron arrangements of atoms in these groups.

   [6 marks]

   (b)

   Describe how standard notation, such as Na⁺ and Cl⁻, is used to represent these ions, and explain why this convention is useful to chemists.

   [6 marks]

   Total for question 4: 12 marks

End of questions