The diagram shows the arrangement of atoms inside an alloy. Larger atoms of a second metal are mixed among the atoms of the main metal. Using the diagram, w...
Question 1 Report
The diagram shows the arrangement of atoms inside an alloy. Larger atoms of a second metal are mixed among the atoms of the main metal. Using the diagram, why is this alloy harder than the pure main metal?
Answer Details
The diagram shows larger atoms of a second metal sitting among the smaller atoms of the main metal, and that is why the alloy is harder: the differently sized atoms stop the layers sliding over each other. In the pure metal every atom is the same size, so the layers slip past one another easily under an applied force and the metal is soft. The larger atoms interrupt the rows, so a far greater force is needed to make the layers move.
The delocalised electrons are not removed by alloying, which is why the alloy still conducts. No electrons are shared in pairs between atoms, so no covalent compound is formed; alloying is mixing, not reacting. The layers in the diagram are clearly not perfectly regular, since the large atoms distort them.
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