What Is The Historical Background Of Arrangement Of Elements?

The history of ideas leading up to the periodic classification of elements is fascinating, but will not be treated here in detail. Those who made memorable contributions in this field are Al-Razi, Doberiner, Newland and Mandeleev. Al-Razi's classification was based on the physical and chemical properties of substances. Doberiner, a German chemist, in 1829, arranged then known elements in groups called triads, as each contained three elemants with similar properties. Newland, who was an English chemist, in 1864, classified 62 elements, known at that time, in increasing order of their atomic masses. He noticed that every eighth element had some properties in common with the first one. The principle on which classification is based was called the law of octaves.

In 1871, a Russian Chemist, Dmitri Mendeleev, gave a more useful and comprehensive scheme for the classification of elements. He presented the first regular periodic table in which elements of similar chemical properties were arranged in 8 vertical columns called Groups. The horizontal rows of the table were called Periods. He also started by arranging the elements in ascending order of their atomic masses and found that elements having similar chemical properties appeared at regular intervals. This scientific observation was called Perodic Law.