A compound is a substance composed of two or more elements that are
chemically combined in a fixed proportion. A molecule must be nonpolar if the molecule has a symmetrical charge distribution. A molecule must be nonpolar if the molecule has a symmetrical charge distribution. An electrolytic cell differs from a voltaic cell because an electrolytic cell requires an outside energy source for a nonspontaneous chemical reaction to occur. As electrons push each other around, the electron orbital clouds form different shapes. Scientists propose that atoms can have up to seven principle energy levels of electrons around the nucleus. This orbital diagram for nitrogen shows how electrons fill the sub-orbitals. Wave Mechanical .This is the electron configuration for the element sulfur, which has 16 electrons. We and everything around us are made of tiny groups of particles, called atoms. While atoms were once thought to be the smallest unit of matter, they are actually made up of much tinier, high-energy, negatively-charged particles circling at a crazy pace around a nucleus of positive and neutral particles. Since the outer-shell (valence) electrons control the chemical properties of a material, it would be useful to understand how they behave.