Question

what do u understand by electrovalant bond write its 4 chracterstics draw the lawis dot structure of na2o mgcl2 cacl2 Al2o3

Answer 1

a bond formed by transfer of electrons between a electro positive element (metals)and a electro negative element (nonmetals).
1 do not dissolve in solvents other than water
2 generally hard but brittle
3 has high boiling and melting point
4 do not conduct electricity in their solid state

Answer 2

Electrovalant bonds are otherwise called as Ionic bond which are formed only in Ionic compounds. These bonds occur due to the transfer of electrons.
Some of the ionic compounds are : NaCl , AlCl3 , etc.

The 4 characterstics of an ionic compound are as follows:

1. They dont conduct electricity in solid state but only n aqueos or molten state
2. They are generally strong and hard
3. They are soluble in water.
4. They are formed by the transfer of electrons due to which bond strength is very     high or strong 

Lewis dot structures please refer the attachments.