Inorganic Chemistry with Help Guides

  Malleability and cohesive force   The mechanical properties of metals are that they are typically malleable and ductile. This snows that there is not much resistance to deformation of the structure. but that a large cohesive force holds the structure together. The cohesive force may be measured as the heat of atomization. Some numerical values of △H° , the heats Of atomization at 25°C, are given in Table. The heats of atomization (cohesive energy) decrease on descending a group in the periodic table Li-Na-K-Rb-Cs, showing that they are inversely proportional to the internudeat distatice. The cohesion energy increases across the periodic table from Group I to Group II to Group III. This suggests that the strefigth of metallic bonding is related to the number of valency electrons. the cohesive energy increases at first on crossing the transition series Sc-Ti-V as the number of unpaired d electrons increases. Continuing across the transition series the number of electrons per a...

  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...

                                  Super Conductivity   https://en.m.wikipedia.org/wiki/File:Periodic_table_with_superconducting_temperatures.jpg                                Metals are good conductors of electricity, and their conductivity increases as the temperature is lowered. In 1911 the Dutch scientist Heike Kamerlingh Oimes discovered that metals such as Hg and Pb became superconductors at temperatures near absoiute zero.  A superconductor has zero or almost zero electrical resistance: It can therefore carry an electric current without losing energy, and in principle the current can flow for ever. There is a critical temperature.  That which the resistance drops sharply and superconduction occurs. Later, Meissner and Ochsen feld found that some superconducting materials will not permit a magnetic ...