Kaysons Publication
- Books Name
- Kaysons Academy Chemistry Foundation Book
- Publication
- Kaysons Publication
- Course
- JEE
- Subject
- Chemistry
Chapter:- 5
Periodic Classification of Elements
Periodic Classification of Elements
Elements are the building blocks of all Substances. There are 118 elements known at present, out of which 98 are naturally occurring. In this chapter, we will study various attempts which have been made to classify the elements from time to time. And finally we will study the modem classification of elements.
Attempts Earlier to Mendeleev
Several attempts have been made to classify elements. We important of which are discussed.
- Lavoisier’s Classification (1789)
- Debereiner's Triads (1817)
- Newlands' Law of Octaves
Lavoisier’s Classification (1789)
It is one of the earliest attempts to classify elements. Lavoisier divided elements into two main divisions, which arc called metals and non-metals.
Debereiner's Triads (1817)
In the year 1817, Johann Wolfgang Dobereiner, a German chemist; identified some groups having three elements each with similar properties. So, he called these groups as triads. When the three elements in a triad were arranged in the order of increasing atomic masses, the atomic mass of the middle element was roughly the average of the atomic masses of the other two elements.
For Example
