-Going downwards in group (akaline earth metals),elements are softer,with lower density and higher melting and boiling points.This is because the atoms become heavier(bigger) and require more energy to melt or boil.
-The reactivity increases downward from top,hence calcium is more reactive than magnesium.They are both silvery white metals,covered with a thin layer of oxide.
Reaction With Water
Magnesium(Mg)
-Does not react with cold water.It reacts with gaseous water(steam) to form magnesium oxide and hydrogen.
magnesium + steam-> magnesium oxide + hydrogen.
Mg(s) + H2O(g) -> MgO(s) + H2(g)
-Magnesium oxide will not dissolve in water.
Calcium(Ca)
-Calcium(and the heavier group metals) will react with cold water. They will sink as they react,unlike the group metals which float.
calcium + water-> calcium hydroxide + hydrogen
Ca(s) + H2O(l) -> Ca(OH)2(s) + H2(g)
-Calcium hydroxide is called slaked lime and will dissolve a little in water to form lime water.
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