A bridge engineer selects metal for an expansion joint carrying heavy traffic. Fig. 1 shows the metallic structure of copper. Positive copper ions are arran...
Question 1 Report
A bridge engineer selects metal for an expansion joint carrying heavy traffic. Fig. 1 shows the metallic structure of copper. Positive copper ions are arranged in layers, surrounded by delocalised electrons. The joint must conduct electricity for a monitoring circuit and must be shaped without breaking.
(a) Give the name of the bonding in copper. [1]
(b) Describe why copper conducts electricity. [2]
(c) Describe why copper can be bent into shape. [2]
(d) Give one other metal property useful for bridge components. [1]
Answer Details
(a) Copper has metallic bonding [1].
(b) Copper contains delocalised electrons [1]. These electrons move through the metal and carry electrical charge [1].
(c) Layers of metal ions can slide past one another [1]. Metallic attraction between the positive ions and delocalised electrons remains, so the metal does not break when bent [1].
(d) A useful additional property is high tensile strength [1]. A high melting temperature or corrosion resistance when alloyed would also be acceptable.
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