Wednesday, April 17, 2013

Ionic Compound

Elements combine together to form compounds. Chemical compounds are of many types, depending upon the bond present in them. Corresponding to the two ways by which any two atoms rearrange to form a compound, two types of bonds are formed.
  1. Ionic bond
  2. Covalent bond.
Ionic bond or electrovalent bond is established by the transfer of one or more valence electrons from one atom to the other.

Thus, ionic bond is a chemical bond formed between two atoms by the transfer of one or more valence electrons from one atom to the other.
This bond is also called as a polar bond.

Formation of an ionic bond:
Formation of an ionic bond can be explained using the following example:
Consider an atom A , which has two electrons in its outermost shell. Another element B, has 6 electrons in its outermost shell.

The atom A has two electrons in excess, to make it to the Noble gas electronic configuration, while atom B has two electrons less to make it to that level.

Now, atom A gives two of the excess electron to atom B, and by this, atom A attains a completely filled shell, while atom B, having attained the required amount of electrons, also reaches the noble gas configuration.

They therefore form an ionic bond between themselves.

List of Ionic Compound Formula-

Lists of ionic-compounds with their formula are:
S.No Ionic-compound Formula
Sodium chloride NaCl
2. Potassium iodide KI
3. Lithium iodide LiI
4. Aluminium oxide Al2O3

Ionic Compound Example-
Some examples of ionic compound are:
Magnesium oxide - MgO – Mg2+, O2-
Calcium Fluoride – CaF2 – Ca2+, 2F-
Aluminium Fluoride – AlF3 – Al3+, F3-

Properties of an Ionic Compound-
  1. Ionic-compounds are three dimensional solids, with well-defined geometrical pattern.
  2. Ionic solids conduct electricity when they are in water solution or in the fused state (molten state).
  3. They are quite hard, have low volatility and high melting and boiling point.
  4. Ionic solids are soluble in polar solvents, due to dissociation of their ions.
  5. Ionic solids are very stable and have very high density.
Is NaCl an Ionic Compound-
Sodium chloride, NaCl is ionic in nature.

The formation of sodium chloride is as follows:

Na has an electronic configuration of 2, 8, 1. The last electron, in the third shell, has to be removed, for it to attain noble gas configuration.

Chlorine has a configuration of 2, 8, 7. It needs one extra electron, which it gains from Sodium, thereby getting the required magic number of ‘8’.

Is Salt an Ionic Compound–

Sodium chloride is also called as common salt. Other than this, most of the compounds, commonly known as salts are formed from the neutralization reaction of an acid and a base. They are all ionic-compounds, because they dissociate into ions in their solution.

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