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Ionic Bonding

Key Questions

  • Answer:

    Just to address this old question....the answer is NO.....

    Explanation:

    Ionic compounds TEND to have high melting and boiling points...why? Because ionic compounds ARE NON-MOLECULAR...i.e. an ionic compound consists of an infinite array of positive and negative ions that are held together by STRONG electrostatic forces.

    An isolated ion in the lattice is attracted to every counterion in the lattice by Coulomb's law of electrostatic attraction. Of course it is also repelled by very other ion of the SAME charge, but if you add all the forces of attraction and repulsion up over the entire lattice, which may certainly be done quantitatively, you can get an estimate of the lattice enthalpy...and this is very ATTRACTIVE....

    Now materials composed of discrete molecules tend to have intrinsically low melting and boiling points, because their molecular, their discrete particle nature, facilitates separation of the individual molecules....

    On the other hand, there are material that are NON-MOLECULAR, but in which the constituent atoms are bound together by STRONG COVALENT bonds in an infinite array....that persists thruout the entire covalent lattice... And the goto example is silicon dioxide #(m.p. 1600# #""^@C)#, or even the diamond structure #(m.p. 3550# #""^@C)#,....in which the individual particles are bound covalently....but the bonding persists over the entire lattice.

    On the other, other hand, there are metals that are bound together by metallic bonding....and even here some metals can be room temperature liquids....what are the examples?

  • Ionic bonds are the bonds which are always formed between a metal and a non-metal.

    For example:-
    Sodium atom has one electron in its outermost shell. Sodium is a metal. Every atom of an element wants to have 8 electrons in its outermost shell/orbits/energy levels excluding some elements like hydrogen and helium because they need 2. The atomic number of sodium is 11. Atomic number is the number of protons present in the nucleus of an atom. In every stable atom the number of electrons is equal to the number of protons.

    Stable means that the atom has not formed an ion yet.

    Therefore, the electronic configuration of sodium is :-
    E.C:- K L M
    2 8 1

    To get 8 electrons in the outermost shell it can lose 1 electron.

    Chlorine is a non- metal and it has atomic number 17.It is a stable atom therefore the number of electrons in chlorine atom is 17.
    electronic configuration of chlorine is:-
    E.C :- K L M
    2 8 7
    To complete its valence shell it would need 1 more electron and sodium wants to lose 1 electron so, one atom of sodium will give its one extra electron to chlorine. Because chlorine atom has more negative charge it will form a negative ion called anion and sodium will have more positive charge on it after losing 1 electron and will form a positive ion called cation .BEING OPPOSITELY CHARGED sodium and chlorine will attract each other and will give rise to an ionic bond and this bond will lead to the formation of an ionic compound called SODIUM CHLORIDE.

    Remember , whenever you will write the name of an ionic compound always write the name of metal first followed by the non- metal.


    video from: Noel Pauller

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