The atomic number of carbon is 6. This means that it has 4 electrons in its outermost shell and it needs 4 more electrons to attain noble gas electronic configuration. It cannot form C4+ cation, as the removal of 4 valence electrons requires a huge amount of energy. The cation formed has 6 protons and 2 electrons. This makes it highly unstable. Carbon cannot form C4− anion, as its nucleus with 6 protons cannot hold 10 electrons. Thus, carbon achieves noble gas electronic configuration by sharing its 4 electrons with other elements—that is, it forms covalent compounds. In ionic compounds, ionic bonds are formed; while in carbon compounds, covalent bonds are formed. Because carbon compounds are covalent in nature, they are bad conductors of electricity; they lack free electrons.