The Periodic Table in Flatland

The $D$-dimensional Coulomb system serves as a starting point for generating generalized atomic shells. These shells are ordered according to a generalized Madelung rule in $D$ dimensions. This rule together with an {\it Aufbau Prinzip} is applied to produce a $D$-dimensional periodic table. A model is developed to rationalize the ordering of the shells predicted by the generalized Madelung rule. This model is based on the introduction of an Hamiltonian, invariant under the $q$-deformed algebra $U_q($so$(D))$, that breaks down the SO($D+1$) dynamical symmetry of the hydrogen atom in $D$ dimensions. The $D=2$ case (Flatland) is investigated with some details. It is shown that the neutral atoms and the (moderately) positive ions correspond to the values $q=0.8$ and $q=1$, respectively, of the deformation parameter $q$.