AP CHEM LAB: CHEMICAL BONDING ? POLAR OR NONPOLAR THEORY: ?Two atoms held together by the mutual attraction of each nucleus to valence shell electrons are said to be chemically bonded. The chemical bond can be represented by the overlap of the electron probability density map of an atomic orbital from each atom to form a molecular orbital capable of containing two electrons. Or said in English, a covalent bond can form. These electrons are shared between the respective atoms. However, the degree of sharing is not necessarily equal. The electronegativity of each atom can be used to approximate its attraction for the electrons and therefore the probability of finding the electrons closer to that nuclei.