<span>
some elements have their outer electrons more tightly bound than
others. Those who have less tightly bound electrons are more reactive.
After this it gets more complex in explaining why they are bound with
different strengths. </span>
A covalent bond is formed between two non-metals that have similar electronegativities.
An <em>i</em><em>o</em><em>n</em><em>i</em><em>c</em><em> </em><em>b</em><em>o</em><em>n</em><em>d</em> is formed between a metal and a non-metal. Non-metals(-ve ion) are "stronger" than the metal(+ve ion) and can get electrons very easily from the metal. These two opposite ions attract each other and form the ionic bond.
Answer:
an uncharged molecule (typically highly reactive and short-lived) having an unpaired valency electron.
Covalent compounds are held together with an intra molecular attraction which is weaker than metallic bond
hence covalent compounds exist as liquids, gases and soft solids
