Periodic Table (The Genesis of Modern Chemistry) - 2

INTRODUCTION

During the late 1860's, Dmitri Mendeleev, a Russian Scientist was working on his model of periodic table. He was so dedicated towards his work that one day he dreamed of periodic table, woke up and drew it on a paper. It was something going in his sub-conscious mind that laid the climbing stairs for such a great discovery. Mendeleev drew the periodic table and made some corrections in the table and proposed his work.

Dmitri Mendeleev’s Periodic Table

· Elements are arranged in order of increasing atomic mass.

· After Fixed Intervals, we observe elements with similar properties.

· Periodic Properties depends on Atomic Mass.

· Periodic Law – The physical and chemical properties of an element is a periodic function of its atomic mass.

Features of Mendeleev's Periodic Table

· 8 vertical columns called Groups and 2 sub-groups (A & B) in Group 1 – 7 and no sub-group in the 8th.

· 7 horizontal rows called periods.

· 8 vertical columns called Groups and 2 sub-groups (A & B) in Group 1 – 7 and no sub-group in the 8th.

· Elements in same group have same valency and in different groups have similar properties.

Merits of Mendeleev's Periodic Table

· Classified 63 elements (All known elements at that time)

· Left Gaps for the addition of later discovered elements.

· Predicted properties of undiscovered elements and named them such as Eka Aluminium (Gallium), Eka Silicon (Germanium) etc.

· Correction of Atomic Masses like Au and Pt.

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