1. 1
   Sodium chloride is formed when sodium metal reacts with chlorine gas, producing a compound in which sodium and chlorine atoms are chemically combined.

   (a)

   Sodium chloride is formed when sodium reacts with chlorine, producing a substance containing atoms of two different elements chemically combined. Which statement correctly defines a compound?

   [1 mark]

   • AA substance in which atoms of two or more elements are chemically combined
   • BA substance made of only one sort of atom
   • CA physical mixture of two or more substances not chemically joined
   • DAny substance that dissolves in water

   (b)

   What generally happens to electrons in the highest occupied energy levels of atoms when they form chemical bonds?

   [1 mark]

   • AThey remain completely unchanged in every type of bonding
   • BThey are destroyed and replaced with new electrons
   • CThey move into the nucleus of one of the atoms
   • DThey are transferred or shared between atoms to achieve the electron arrangement of a noble gas

   (c)

   Explain why sodium and chlorine atoms combine to form sodium chloride, in terms of their electron arrangements.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   A student compares three substances: magnesium oxide, a bar of pure iron, and water, to identify which type of bonding is present in each.

   (a)

   In magnesium oxide, bonding involves electrons being transferred completely from one atom to another. What is this type of bonding called?

   [1 mark]

   • AMetallic bonding
   • BCovalent bonding
   • CIonic bonding
   • DHydrogen bonding

   (b)

   In the bar of pure iron, electrons are described as being delocalised, meaning they are free to move throughout the whole structure. What is this type of bonding called?

   [1 mark]

   • AIonic bonding
   • BMetallic bonding
   • CCovalent bonding
   • DSimple molecular bonding

   (c)

   Water contains covalent bonds between hydrogen and oxygen atoms. Describe what covalent bonding involves, and explain how it differs from the ionic bonding seen in magnesium oxide.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   Calcium oxide is formed from calcium, a metal, reacting with oxygen, a non-metal, while carbon dioxide is formed from carbon and oxygen, both of which are non-metals.

   (a)

   Calcium oxide is formed from calcium (a metal) and oxygen (a non-metal), while carbon dioxide is formed from carbon and oxygen, both non-metals. State the type of bonding present in calcium oxide and in carbon dioxide, explaining your reasoning based on the elements involved in each.

   [3 marks]

   (b)

   Explain in detail how the bonding in calcium oxide differs from the bonding in carbon dioxide, referring to how each achieves a noble gas electron arrangement.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A student is comparing three substances with different types of bonding: an ionic compound, a covalent compound, and a metal, in order to identify the general features that distinguish ionic, covalent and metallic bonding.

   (a)

   Describe the three main types of chemical bonding: ionic, covalent and metallic, explaining how each achieves a stable arrangement of electrons for the atoms or ions involved.

   [6 marks]

   (b)

   Given an unknown substance formed from combinations of a metal and a non-metal, two non-metals, or metal atoms alone, explain how you would decide which type of bonding, ionic, covalent or metallic, is most likely present, justifying your reasoning.

   [6 marks]

   Total for question 4: 12 marks

End of questions