General outer electronic configuration
Elements present in groups will have a general electronic configuration which would be followed by the elements present in the periodic table.Given above is the outer electronic configuration of the groups present in the table.
The properties of the elements in a periodic table exhibit trends. These trends can be predicted using the periodic table and can be explained and understood by analyzing the electronic configurations of the elements.
Elements tend to gain or lose valence electrons to achieve stable octet configuration. Stable octets are seen in the inert gases or noble gases, of Group VIII of the periodic table. In addition to this activity, there are two other important trends. First, electrons are added one at a time moving from left to right across a period. As this happens, the electrons of the outermost shell experience increasingly strong nuclear attraction, so the electrons become closer to the nucleus and more tightly bound to it.
Second, moving down a column in the periodic table, the outermost electrons become less tightly bound to the nucleus. This happens because the number of filled principal energy levels (which shield the outermost electrons from attraction to the nucleus) increases downward within each group. These trends explain the periodicity observed in the elemental properties of atomic radius, ionization energy, electron affinity and electronegativity.
By observing the trends in the atomic radii of the elements in a period and those within a group of the periodic table we can predict the relative sizes of atomic and ionic radii within an isoelectronic series. We can also estimate certain physical properties of a particular element if the properties of elements above and below the given element in a group of elements are known.
Let us explore the variations in atomic radius, ionization energies, electron affinities in a periodic table.