If we go on from neon in the periodic system we come to _sodium_ (11). When the sodium nucleus captures electron No. 11, this cannot find room in the neon-architecture formed by the first ten electrons. Since the eleventh electron thus cannot find a place in either a 2₁ or a 2₂ orbit, it is bound in a 3₁ orbit (cf. Fig. 29 and diagram at the end). The atom then has a character like that of the lithium atom, and we can therefore understand the chemical relationship between the two elements, which are both monovalent electropositive metals. We shall not dwell longer upon the individual elements of the atomic series. If we pass from neon through sodium (11), magnesium (12), aluminium (13), etc., to _argon_ (18), we get what is essentially a repetition of the situation in the series from lithium to neon. We first get two orbits of the 3₁ type in magnesium, a 3₂ orbit is for the first time added in aluminium, and for the atomic number 18, eight 3-quantum orbits, together with the eight orbits of the inner 2-quantum group and the two of the innermost 1-quantum group, give the symmetric architecture of _argon_ (cf. table on p. 196, and diagram at the end). The architecture of the argon atom is in a certain sense less complete than that of the neon atom. In argon there are indeed four orbits of the 3₁ type and four of the 3₂ type, but the third kind of 3-quantum orbit, the circular 3₃ one, is missing. Nor does it appear in the next element, _potassium_ (19). The electron No. 19 prefers, instead of the 3₃ orbit, the 4₁ orbit, which consists of oblong loops and which gives a firmer binding because it dives in among the electrons bound earlier, while the circle 3₃ would lie outside them all. We thus obtain an atom of type similar to the lithium and sodium atoms. But the slighted 3₃ path lies, so to speak, on the watch to steal a place for itself in the neutral atom, and this has grave results for the subsequent development. Even in _calcium_ (20), after the first eighteen electrons are bound in the argon architecture, both the nineteenth and the twentieth go into a 4₁ orbit, and the behaviour of calcium is like that of magnesium. But since the increasing nuclear charge means for the electron No. 19 a decrease in the dimensions and an increase in the binding of the orbits corresponding to the quantum number 3₃, a point will finally be attained where the 3₃ orbit of the nineteenth electron lies within the boundaries of what may be called the argon system, _i.e._, the architecture corresponding to the first eighteen electrons, and corresponds to a stronger binding than a 4₁ orbit would do. In _scandium_ (21) the 3₃-type orbit occurs for the first time in the neutral atom and will not only come into competition with the 4₁ type, but will also cause a disturbance in the 3-quantum groups, which in the following elements must undergo reconstruction. As long as this lasts the situation is very complicated and uncertain.