We have already discussed some aspects of the nature of metals. In Topic 16 we saw that the valence electrons in the metallic bond are free to move randomly between the positive ions, thus providing an attractive force that holds the metal together. We noted that the ions do not all have to be of the same kind, which means that different elements can be combined to form alloys. In Topic 18 we saw that the freedom of movement of the valence electrons is responsible for the high thermal conductivity of metals, and in Topic 29 we shall see that it is responsible for their electrical conductivity as well. In Topic 22 we noted that the generally non-specific and non-directional nature of the metallic bond means that, as far as any particular metal atom is concerned, one neighbour is as good as any other. As a result of this, most metals have the ability to undergo plastic deformation before they break because individual metal atoms can change their neighbours without affecting the integrity of the metal as a whole (see Figure 21.6).
KeywordsZinc Nickel Brittle Hexagonal Ductility
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