Periodic table

The modern Periodic table is an arrangement of elements in the order of their atomic numbers. This is in accordance with the modern periodic law that states that the properties of elements are a periodic function of their atomic numbers (and not atomic masses as suggested by the Russian bearded chemist, Dmitri Mendeleev).

Features of the Periodic Table

• There are horizontal rows called periods and vertical columns known as groups. In the table, there are eight groups and seven periods;
• The groups are labeled I, II, III, IV, V, VI, VII while the eighth group is called group O;
• The number of valence electrons in the outer shell dictates the group to which an element belongs.  Thus, sodium whose outer shell has only one electron belongs to group I, magnesium belongs to group II because there are two electrons in its outer shell and so on;
• The number of energy levels or orbits of the atoms in an element determines the period to which an element  is placed in the periodic table;

Diagram

• In the periods 6 and 7, respectively can be found groups of elements collectively called lanthanides and actinides series.
• Group I, II, and III members are metals.  Group I members are otherwise called alkali metals; Group II elements are the alkaline earth metals while the group III members are called poor metals;
• Group VII elements are called halogens.

The elements in the periodic table are also categorized in respect to the orbitals in which electrons are being filled.  Thus, the so called s-block that consists of 2 columns (i.e. the groups I and II) where there are elements that are filling the single orbital with maximum of 2 electrons.  This is coloured yellow in the diagram

The p-block consists of 6 columns (i.e. from groups III through O) and contains elements that have a maximum of six electrons in the p-orbital.  This is coloured purple in the diagram;

The d-block consists of 10 columns (i.e. those elements found located between groups II and III) that are filling the d-orbital.  These elements are sometimes called the transition elements.  It is coloured green in the diagram;

The f-block are the blocks at the foot of the periodic table and is coloured dark blue in the diagram.  They are the elements that are filling the f-orbital and are sometimes called the lanthanides and the actinides.

These are the various blocks of the periodic table.

(to be continued)