Pure substances have different structures depending on the type of bonding they have. The structure of a substance decides what its physical properties will be
Ionic-Because of the very strong bonds between ions,ionic compounds have high melting and boiling points e.g sodium chloride melts ar over 800 degrees celcius, iron chloride at 677 degrees celcious is its melting point and calcium oxide melts at 2707 degrees celcious.As ionic compounds are made of charged ions they can conduct electricity but only if the ions can move so if its in molten the ions can move and so can conduct eectricity also it its dissolved in water the ions can move. Its cheaper to dissolve and takes less energy
when salt is put in water the H2O molecules pull ions apart to make a solution this lets the ions move around. water alone does not conduct electricity and salt alone does not conduct electricity but salt and water do.
simple molecular sustances
there are substances like carbon dioxide CO2,water H2O and methane CH4 which are always made of simple molecules whether they are solids liquids or gases and they are non metals
there are very strong covalent bonds between atoms but weaker forces holding the molecules. when waters bonds breaks its the intermolecular forces that…