Question

What is Mendeleev's periodic table? Explain.

Answer 1

Mendeleev's periodic table

• Mendeleev's original periodic table was published in the year 1869 and claimed the famous periodic law that “Element properties are a periodic function of their atomic weight”.
• Mendeleev placed elements in the order of their atomic weights in the form of a table known as the Periodic table of Mendeleev.
• Mendeleev tried to co-relate the atomic masses with their physical and chemical properties.

Arrangement of elements in the Mendeleev's periodic table

• Elements with similar properties were found in the same vertical column. In a horizontal line, the elements are arranged in an increasing atomic mass value.
• The horizontal rows are called a ‘period’, and the vertical columns are called a ‘group’.
• The elements with similar properties were placed in the same group.
• There are 8 groups indicated by Roman numbers I, II, III, IV, V, VI, VII, and VIII, and the elements belonging to the first seven groups have been divided into sub-groups designated as A and B on the basis of similarities in properties.
• Noble gases could be easily placed in a separate group called the zero group (noble gas elements have zero valencies) without disturbing the main periodic table.
• Many gaps were left in the periodic table for the undiscovered elements which were identified later on and were placed in their respective positions.