Fig. 1 shows a model of sodium metal before it reacts with water in a demonstration. The dots between the sodium ions represent outer electrons that are not...
Question 1 Report
Fig. 1 shows a model of sodium metal before it reacts with water in a demonstration. The dots between the sodium ions represent outer electrons that are not held by one atom.
(a) Name the type of bonding in sodium metal. [1]
(b) What is the name given to the electrons shown as dots? [1]
(c) Use Fig. 1 to suggest why sodium conducts when it is solid. [1]
(d) Give the charge on a sodium ion. [1]
(e) Complete the sentence. Metallic bonding is the attraction between positive ions and ______ electrons. [1]
This cross-section is from a high-temperature ceramic crucible. Fig. 1 compares a giant ionic lattice with separate water molecules that can enter cracks in the ceramic.
(a) Name the particles in the left-hand structure. [1]
(b) Give one reason why the ionic ceramic can withstand high temperature. [1]
(c) What type of bond joins oxygen to hydrogen in a water molecule? [1]
(d) Suggest why liquid water can conduct a little when impurities are present. [1]
Answer Details
Sodium metal
- (a) Sodium has metallic bonding. [1]
- (b) The dots represent delocalised electrons. [1]
- (c) Sodium conducts as a solid because electrons can move and carry charge. [1]
- (d) A sodium ion has charge 1+. [1]
- (e) Metallic bonding is the attraction between positive ions and delocalised electrons. [1]
Ionic ceramic and water
- (a) The particles on the left are ions. [1]
- (b) Strong electrostatic attractions between oppositely charged ions need much energy to overcome, so the ionic ceramic withstands high temperature. [1]
- (c) Oxygen and hydrogen in water are joined by a covalent bond. [1]
- (d) Impurities dissolved in water provide mobile ions, allowing liquid water to conduct a little. [1]
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