Formation of Ionic Compounds
These notes are based on the chapter metals and non-metals from class 10 science NCERT book and CBSE syllabus.
- Formation of magnesium chloride
- Formation of calcium chloride
- Formation of calcium oxide
- Properties of ionic compounds
Formation of Magnesium Chloride (MgCl2)
The atomic number of magnesium is 12
Electronic configuration of magnesium: 2, 8, 2
Number of electrons in outermost orbit = 2
Valence electron = 2
Atomic number of chlorine = 17
Electronic configuration of chlorine: 2, 8, 7
Electrons in outermost orbit = 7
Therefore, valence electrons = 7
Magnesium loses two electrons in order to obtain stable electronic configuration. Each of the two chlorine atoms gains one electron lost by magnesium to obtain stable electronic configuration. The bonds so formed between magnesium and chlorine are ionic bonds and compound (magnesium chloride) is an ionic compound.
Formation of calcium chloride: (CaCl2)
Atomic number of calcium is 20.
Electronic configuration of calcium: 2, 8, 8, 2
Number of electrons in outermost orbit = 2
Valence electron = 2
Valence electrons of chlorine = 7
Calcium loses two electrons in order to achieve stable electronic configuration. Each of the two chlorine atoms on the other hand gains one electron losing from calcium to get stability. By losing of two electrons calcium gets two positive charges over it. Each of the chlorine atoms gets one positive charge over it.
The bonds formed in the calcium chloride are ionic bonds and compound (calcium chloride) is an ionic compound. In similar way, Barium chloride is formed.
Formation of Calcium oxide (CaO)
Valence electron = 2
Atomic number of oxygen is 8
Electronic configuration of oxygen is: 2, 6
Number of electrons in outermost orbit = 6
Valence electron = 6
Calcium loses two electrons and gets two positive charges over it in order to get stability. Oxygen gains two electrons, lost by calcium and thus gets two negative charges over it.
Bond formed between calcium oxide is ionic bond. Calcium oxide is an ionic compound. In similar way, magnesium oxide is formed.
Properties of Ionic compound
- Ionic compounds are solid. Ionic bond has greater force of attraction because of which ions attract each other strongly. This makes ionic compounds solid.
- Ionic compounds are brittle.
- Ionic compounds have high melting and boiling points because force of attraction between ions of ionic compounds is very strong.
- Ionic compounds generally dissolve in water.
- Ionic compounds are generally insoluble in organic solvents, like kerosene, petrol, etc.
- Ionic compounds do not conduct electricity in solid state.
- Solution of ionic compounds in water conduct electricity. This happens because ions present in the solution of ionic compound facilitate the passage of electricity by moving towards opposite electrodes.
- Ionic compounds conduct electricity in molten state.