Page 250 - Reliance Foundation School Koparkhairane - School Magazine - Zenith

MENDELEEV’S PERIODIC TABLE - 150TH YEAR

Chemistry is a branch of science that studies the physical and chemical
properties of substances. It tells us about states of matter of various
substances present around us that is ice (solid), water (liquid) and vapour

(gas). It takes us to the smallest indivisible particle of matter an atom or to
find the position of an electron (Quantum chemistry). It makes our life
beautiful by imparting colour to food items like yellow (Metanil) etc.

Molecular study of biomolecules like carbohydrates, proteins, vitamins etc.
keeps us healthy and fit. In Chemistry, we also study compounds that are
made up of smaller units called elements. Different elements come together
to form compounds but wonderfully compounds have altogether different
properties than their parent elements. All these elements form a vital part of

our lives and they are systematically represented in the Periodic Table.

The discovery of elements has an interesting history. The first element to be
discovered was Phosphorus by the German scientist Hennig Brand in 1669.

He called the substance 'cold fire' because it was luminous and glowed in the
dark. Later different scientists discovered various elements from natural
sources. This gradually necessitated the need to classify the elements for

their proper understanding based on their characteristics and soon scientists
started classifying these elements based on their similarities or differences
with each other.

Johann Dobereiner (1817) classified elements on basis of atomic mass and
he gave the concept of a 'triad' to the scientific society. This triad says that
when three elements are arranged in the increasing order of their atomic
mass then the atomic mass of the middle element is the average of the
atomic mass of the other two elements. In 1862, Alexandre-ÉmileBéguyer

de Chancourtois a French geologist was the first to arrange elements in the
increasing order of their atomic weight, the chemical properties were
repeated at regular intervals and so it came to be called as the periodic table.

John Newland (1865) classified 56 known elements using the octaves of
music for classifying elements. As per his classification, when elements are
arranged in the increasing order of their atomic masses, every eight element
shows properties similar to that of the first element.

Dmitri Mendeleev was a Russian chemist and inventor. In 1869 he wrote
out the known elements on cards and then arranged them in columns and
rows according to their chemical and physical properties. He is considered
the father of the Periodic Table. He was able to classify only 63 elements

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