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Solids. Substitutional. Interstitial. Metallic Crystals Alloys – mixtures of metals – done to strengthen or make a metal less brittle or subject to oxidation. 2 types Substitutional – when metal atoms are of similar size
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Solids Substitutional Interstitial • Metallic Crystals • Alloys – mixtures of metals – done to strengthen or make a metal less brittle or subject to oxidation. • 2 types • Substitutional – when metal atoms are of similar size • Interstitial – when one atom is smaller than the other, fills in the spaces between the larger ones
Solids • Metallic crystals • Substitutional alloy • Silver alloyed with gold, replace one set of attractive forces with an almost equal set of attractive forces with the added metal. • Result: alloy has properties that tend to fall somewhere between the two separate metals
Solids • Metallic crystals • Interstitial alloys • Incorporate one atom into the existing structure with little change in volume- results in increased density • Increases total attractive forces in the alloy • Usually stronger and harder than original materials
Solids • Ionic Crystals • Attraction of a cation and an anion is the strongest attractive force known in chemistry. • Alternating positive & negative ions • Almost all ionic compounds are solids with rigid crystal structures (lattices) • Take a large amount of lattice energy to separate the ions!