A good tutorial on chemical bonds can be found at www.KahnAcademy.org
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When valence electrons are shared by two atoms, a "covalent bond" is formed. If the shared electrons spend more time with one atom than the other, the result is a" polar covalent bond."
In your example of HCl, the single electron of the H atom is transferred completely to the Cl atom, making the two atoms into ions: H+ and Cl-. Those two ions form a strong bond, called ionic.
If you have more examples to consider, please show what you think the answers are, and why you think so.