-------+------+------------------------------------------------------+ | | Quantum Numbers. | |Atomic+---+---+---+---+---+---+---+---+---+---+---+---+---+--+ |Number| 5₁| 5₂| 5₃| 5₄ | 5₅| 6₁| 6₂| 6₃| 6₄| 6₅| 6₆| 7₁ | 7₂| 7₃| -------+------+---+---+---+---+---+---+---+---+---+---+---+---+---+--+ Helium | 2 | | | | | | | | | | | | | | | Neon | 10 | | | | | | | | | | | | | | | Argon | 18 | | | | | | | | | | | | | | | Krypton| 36 | | | | | | | | | | | | | | | Xenon | 54 | 4 | 4 | - | - | - | | | | | | | | | | Niton | 86 | 6 | 6 | 6 | - | - | 4 | 4 | - | - | - | - | | | | ? | 118 | 8 | 8 | 8 | 8 | - | 6 | 6 | 6 | - | - | - | 4 | 4 | -| -------+------+---+---+---+---+---+---+---+---+---+---+---+---+---+--+ The elements _fluorine_, _oxygen_ and _nitrogen_ can attain the ideal neon-architecture by binding respectively one, two and three additional electrons. Naturally they do not become neon atoms, but merely negative atomic ions with single, double or triple charge; and their tendency in this direction appears in their character of monovalent, divalent and trivalent electronegative elements respectively. If we return to carbon it can probably not become a tetravalent negative ion by binding four free electrons; but in the typical carbon compound, methane (CH₄), the neon ideal is realized in another manner. In fact, it is reasonable to assume that the four electrons of the hydrogen atoms together with the six of the carbon atom give approximately a neon-architecture. The four hydrogen nuclei naturally cannot be combined with the carbon nucleus; the mutual repulsions keep them at a distance. They will probably assume very symmetrical positions within the electron system which holds them together. The nitrogen atom may in a similar way find completion in a neutral molecule with neon-architecture, if it unites with three hydrogen atoms to form ammonia NH₃; but the three hydrogen nuclei, although having symmetrical positions, will not lie in the same plane as the nitrogen nucleus. The electric centre of gravity for the positive nuclei will therefore not coincide with the centre of gravity for the negative electron system. The molecule obtains thus what might be called a positive and a negative pole, and this dipolar character appears in the electrical action of ammonia (its dielectric constant). Something similar holds true for the water molecule, where, in a neon-architecture of electrons, in addition to the oxygen nucleus in the centre there are two hydrogen nuclei which are not co-linear with the oxygen nucleus.