|  Terminology:  Magnesium – магний  Calcium – кальций  Burn – сжигать  Limestone – известняк  building –строительство  minerals-минералы  chalk-мель   Atomic structure:  +12Mg  1s22s22p63s2  +20Ca 1s22s22p63s23p64s2    Calcium minerals:  CaCO3 – chalk  CaSO4*2H2O – gypsum  Ca3(PO4)2 – phosphorite or apatite  CaF2 – fluorite  Magnesium minerals:  MgCO3— magnesite  MgCO3* CaCO3 – dolomite  Mg2SiO4 – olivine  MgO*2H2O* 2SiO2– asbestos  KCl*MgCl2*6H2O– carnallite   Physical properties  Magnesium is a shiny, silver or gray colored metal that is light inweight and strong. Th density of magnesium is 1.738 g/mL, which means the metal will sink in water, but it is still relatively light weight. Chemical Properties: Magnesium is a silvery whitemetal.    
   Calcium is a fairly soft metal with a shiny silver surface when first cut. The surface quickly becomes dull as calcium reacts with oxygen to form a coating of white or gray calcium oxide. Calcium's melting point is 850°C (1,560°F) and its boiling point is 1,440°C (2,620°F).    Chemical properties  Mg: White  Ca: Dark red  2Mg +O2→2MgO    Mg +Cl2→MgCl2      Magnesium reacts slowly with cold water, forming magnesium hydroxide and bubbles of hydrogen:    Mg +2H2O →Mg(OH)2+H2    It reacts vigorously if steam is passed over the heated metal, forming magnesium oxide and hydrogen:  Mg +H2O →MgO +H2    Magnesium. Slight reaction. pH=9    MgO +H2O →Mg(OH)2 t0C= 100-125°C.    2Ca+O2→2CaO (calcium oxide)  Ca+Cl2→CaCl2 (calcium chloride)  Magnesium- Uses    Calcium- Uses |