Covalent bond = a bond in which the electrons are shared by the partner atoms.

Polar bond = simply a type of covalent bond in which the electrons are shared but not equally. This happens when two different atoms come together, such a C and O. Each atom has a different ability to draw electrons to itself when it shares electrons (that drawing ability is

called Electronegativity).

Polar covalent bond = same as a “polar bond”.

Nonpolar bond = two of the same atoms come together, such as the diatomic molecule N2, or triatomics such as O3, etc. A nonpolar covalent bond could be viewed as having “pure” covalent character. There is perfectly equal sharing.

Polar molecule = a molecule in which the polar bonds are disposed in

such a way that it imparts an asymmetry to the molecule as a whole. That

is, it gives the whole molecule a Dipole Moment:

example: water H-O-H has two polar bonds. Since this molecule is

Bent, those two polar bonds ADD TOGETHER to produce a molecule with a

dipole moment. That is, a polar molecule.

example: carbon dioxide O=C=O has two polar bonds also. Since this

molecule is Linear, those two polar bonds ADD TOGETHER to cancel each

other out, to produce a molecule with NO dipole moment. That is, a

nonpolar molecule.

example: carbon tetrachloride CCl4 has four very polar bonds

but these bonds are pointing to the corners of a tetrahedron, and form a very

symmetric arrangement. The polarity cancels itself out, and the molecule is

NONPOLAR.

Polar And Nonpolar Covalent Bonds

Nonpolar Covalent

Nonpolar covalent bonds form when electrons are shared equally. When the two atoms sharing electrons are identical, such as in oxygen gas (O2), the electronegativities are identical, and both atoms pull equally on the electrons. Polar Covalent bonds form when electrons are shared unequally. Atoms in this kind of bond have electronegativities that are different, and an unequal distribution of the electrons results. The electrons forming the bond are closer to the atom with the greater electronegativity and produce a negative charge, or pole, near that atom. The area around the atom with the weaker pull on the electrons produces a positive pole. In a molecule of water(H2O), for example, electrons are shared between the oxygen atom and each hydrogen atom. Oxygen, with a greater electronnegativity, exerts a stronger pull on the shared electrons than does each hydrogen atom. This unequal distribution of electrons crates a negative pole near the oxygen atom and positive poles near each hydrogen atom.

covalent: between 2 nonmetals. Electrons are shared equally because the atoms have the same electronegativity.

polar covalent: between 2 nonmetals. Electrons are not shared equally because one of the atoms has more electronegativity than the other.