Ionic compounds

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Super Conductivity

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 When two metals are heatec;l together, or a metal is mixed with a nonmetallic element, then one of the following will occur:  l. An ionic compound may be formed.  2. An interstitial alloy may be formed.  3. A substitutional alloy may be formed.  4. A simple mixture may result.  Which of these occurs depends on the hemical nature of the two elements concerned, and on the relative sizes of the metal atoms and added atoms.
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  General Properties of metals   All metals have characteristic physical properties:  1. They are exceptionally good conductors of electricity and heat.  2. They have a characteristic metallic lustre - they are bright, shiny and highly reflective.  3. They are malleable and ductile.  4. Their crystal structures are almost always cubic close-packed, hexag-onal close-packed, or body-centred cubic.  5. They form alloys readily. Conductivity  All metals are exceptionally good conductors of heat and electricity. Electrical conduction arises by the movement of electrons. This is in contrast to the movement of ions which is responsible for conduction in aqueous solution or fused melts of ionic compounds like sodium chloride, where sodium ions migrate to the cathode, and chloride ions migrate to the anode. In the solid state, ionic compounds may conduct to a very small extent (semiconduction) if defects, are present in the crystal. There is an enormous di...
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