1.SCHOOL OF ELEMENTS

1.school of elements

There are four scientists:

1. Johann Wolfgang Dobereiner.

2. Newland.

3. Dimitri Mendeleev.

4.Henry Moseley.

1.1 Dobereiner's triads: In dobereiner's Triads, atomic mass of the middle element was approximately the mean of the atomic masses of other two elements.

1.2 Newlands' Octaves: "When the elements are arranged in an increasing order of their atomic masses,the properties of the eighth element are similar to the first."

1.3 Mendeleev's Periodic Law: The physical and chemical properties of elements are a periodic function of their atomic masses.

1.4: Moseley's Law (Modern Periodic Law):"The chemical and physical properties of elements are a periodic function of their atomic numbers."

As of today,118 elements are known but more and more information about their properties is being discovered.It was difficult to organize these elements and hence scientist made various attempts to  classify them.

Some Questions.....

1. State Newlands' 'Law Of Octave'.

2. State Mendeleev's periodic law.

3. State Modern periodic law.

1.1 Dobereiner's Triads: Dobereiner was a German scientist. He was professor of chemistry and pharmacy at the University of Jena. He found some groups of three elements which showed similar properties. These groups were called as triads. 

Dobereiner could identify only some triads from the elements known. Other triads did not obey Dobereiner's rule. so, the system of triads was not useful.

1.2: Newlands' Octaves: British Chemist Newlands studied at  Royal College of Chemistry. After failure of Dobereiner's triads, the next attempt to classify elements was done by Newlands.