A molecule that has a partial positive and a partial negative end because of unequal sharing of electron

The molecule you're referring to is known as a polar molecule. Polar molecules occur when there is an electronegativity difference between the bonded atoms. Electronegativity is the measure of the ability of an atom to attract the shared pair of electron towards itself in a covalent bond.

When the electronegativity difference is large, the more electronegative atom pulls the shared electron pair closer to itself. This creates a region of slight negative charge (δ-) near the more electronegative atom and a region of slight positive charge (δ+) near the other atom, resulting in a dipole moment, a measure of the polarity of the molecule.

Water (H2O) is a common example of a polar molecule. The oxygen atom is more electronegative than the hydrogen atoms, so the shared electrons spend more time closer to the oxygen atom, giving it a partial negative charge and leaving the hydrogen atoms with a partial positive charge.