Third Row Of Periodic Table Research Articles

The 4s and 3d subshells: Which one fills first in progressing through the periodic table and which one fills first in any particular atom?

In this paper, first we discuss an old problem in teaching electron configuration of transition metals and the order in which the orbitals are filled. Then we propose two simple computational experiments, in order to show that in the case of first row transition metals and the main group elements after them, the electrons occupy the 3d subshell before the 4s. It is shown that if we begin with the bare nucleus of above elements in the vacuum and then continue with adding the electrons the 19th electron firstly occupies the 3d subshell and not the 4s. Indeed, the 4s subshell in the third row of periodic table only fills first in the case of K and Ca atoms. However, the 3d subshell in transition metals and the main group elements after them is more stable than 4s and so fills first. Thus there is no scientific reason to write the electron configuration of transition elements as [Ar] 4s 3d and the correct form is [Ar] 3d 4s.

Optimum valence bond scheme: theoretical study of small clusters of elements in the second and third row of periodic table

Using optimum valence bond scheme which reduces the computation effort, we study systematically the properties of the critical structures (critical points) of small clusters (up to four atoms) of elements in the second and third row of the periodic table. We also show the evolution process of the clusters from two atoms to four atoms. By examining the electronic structures of all clusters, we can understand why the four-atom clusters for specific elements can have three-dimensional structures with Td symmetry. More interestingly, comparing the variation of the binding energy of such small clusters with the melting points and boiling points of corresponding pure element materials, we can understand the effect of the critical structures in the melting and boiling processes.