Explain how the properties of a molecule are determined by the atoms it contains and their arrangement. Discuss polar and nonpolar molecules.

Answer:

Molecules are held together by shared electron pair, meaning it is form via covalent bond. Covalent bond is directional, meaning that the atons adopt specific positions relative to one another so as to maximize the bond strengths. As a result molecules have definite fairly rigid structure or sparial distribution of its atom. The properties of molecules correlate with their structures, take water molecule as an example, it has a bent structure and therefore has a dipole moment, whereas the carbon dioxide molecule is linear and has no dipole moment. 

Polarity occurs when there is a separation of positive and negative charges due to the unequal attraction that the two atoms have for the bonded electrons. The atom with larger electronegativity will have more pull for the bonded electrons than will the atom with smaller electronegativity; the greater the difference in the two electronegativities, the larger the dipole.