Saturday, February 21, 2009

Circular Form of Periodic Table

Study of atomic elements reveals the presence of a systematic structure within the atom. The chemical behavior of the atom is determined by the count of the electrons present in it and more precisely the valence electrons. This internal electronic structure is theoretically represented in the form of electronic configuration of the element. Every element has its unique electronic configuration. The presence of similarities and symmetries in electronic configuration of different atomic elements leads to the classification of elements into families.

In 1869 Russian Chemist Mandeleeff arranged the elements in a form of table by considering atomic weight as the periodicity parameter. From the relationship embodied in the table, he predicted the existence as well as the properties of the elements then unknown. However in 1913 Henry Moseley identified that chemical and physical properties of the elements are more dependent on the number of electrons rather than atomic weight. He referred the number of electrons in an element as atomic number and modified the basis of classification of elements from atomic weight to atomic number. With theoretical advances such as electronic configuration of elements it was established that atomic number is the basis of periodicity.

The Modern form of Periodic table is based on the electronic configuration of the elements with priority to the valence electrons. It consists of 18 vertical columns called as groups and 7 horizontal rows called as periods. Also keeping in mind the importance of the outer shell electrons the table is divided into blocks namely s, p and d blocks. With all the advantages over Mandeleeff’s Periodic Table the Modern form of periodic table has gained wide popularity as standard representation of elements. Various aspects that favor Modern Periodic table are size, chemical behavior, atomic radius, ionization energy, electron affinity, electro negativity metallic character, binding energies, diagonal relationships etc.

The major disadvantage of the Modern Periodic table is its shape itself. Rectangular arrangement of elements puts constraints in describing the properties of the elements such as shape, atomic structure, nucleus, etc. With the developments in the nucleon shell model it is far more informative to have a complete periodic table showing both nucleon as well as electronic structure.

To incorporate more and more amount of properties in a form of arrangement of elements a new circular of periodic table is put forward. The aim of this circular form of table is make a student understand the atomic structure and its properties along side the periodic table. This table does include all the properties of the Modern Periodic table meanwhile adding further advantages.

Silent features of Circular Form of Periodic Table:

  1. It clearly reflects the atomic structure of an element along with the electronic configuration. The fact that it follows Bohr Circular atomic structure model, it becomes easy for a student to visualize the way electrons are arranged.
  2. It shows pictorially the arrangement of electrons outside the nucleus. The model depicts the circular orbits in which electrons revolve around the nucleus.
  3. Atomic nucleus is also shown in the circular form of periodic table, which was absent in any modern form of periodic table.
  4. Once the nucleon shell model gets fully developed, in can be incorporated in the table easily.
  5. Properties like atomic radius, ionization energy, electron affinity, electro negativity metallic character, binding energies, diagonal relationships can be explained in far more convenient way using Circular form of Periodic Table. (Refer any standard chemistry textbook to know these terms!!)
  6. Since in the atoms, as the orbits are filled with electrons in the order n = 1, n =2 ,n=3,… the shells are formed. There are 7 shells in the table each representing a unique energy level. (Each shell is shown with a unique color)
  7. The Circular periodic table consists of 18 sectors called as groups similar to Modern periodic table.
  8. Considering the size and shape of hydrogen and helium atoms they are shown much closer to nucleus.


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