Graphite and carbons are produced by pyrolysis of organic substances which in addition to hydrogen may contain 0, N, S, or other heteroatoms which can remain in the resulting carbon structure up to high temperatures. The boron atom has three electrons in the outer shell, two s electrons and one p electron. The boron atom can be regarded as ideal for substitution for a carbon atom in graphite: with its three electrons, it forms three coplanar orbitals, exactly as the carbomatom in graphite. Nongraphitizable carbons, often referred to as hard carbons, consist of small elementary domains completely disoriented with respect to each other and strongly bonded by covalent C-C bonds. Silicon is the nearest neighbor to carbon in the fourth column of the periodic chart of the elements. Phosphorus is an element in the fifth column of the periodical table of elements, immediately below nitrogen, which is next to carbon.