In 1817, a German chemist, Johann Wolfgang Dobereiner tried to arrange the elements with same properties into groups. He found out that some groups had only 3 elements and called them 'Triads'. He showed that when the 3 elements were written in their order of increasing atomic masses……the Atomic Mass of the middle element was roughly* the average of the masses of the other two elements.
For example:
Li Na K
6.9 23.0 39.0
Average of Li & K = 22.95, i.e., *roughly 23.0
But since all the elements known then also couldn't be classified as this......'Dobereiner's Triads', as the table is known……wasn't useful……but the attempts of Dobereiner encouraged other chemists to correlate the properties of elements with their atomic masses.Of course, three elements (the Greek prefix tri has the significance three).
Some Dobereiner's triads:
Cl, Br, I
Ca, Sr,Ba
Li,Na,K
S, Se, Te
The only of merit Dobereiner's research was that it made chemists look at elements in terms of groups of elements with similar chemical and physical properties. This eventually led to rigorous classification of elements and the modern Periodic Table of elements, as we now know it, was discovered.
After the acceptance of atomic mass values universally attempts were made to find out relations between properties of the various elements and their atomic masses in 1829 j.w Dobereiner discovered that within group of elements of three closely related in chemical properties the atomic masses are either nearly the same (eg,Iron,cobalt and nickel) or the atomic mass of the middle element is approximately the arithmetic mean of other two elements. these are called Dobereiner's triads,
Examples:
Li, Na, K
C, N, O
Ca, Sr, Ba
Cl, Br, I
S, Se, Te
Mn, Cr, Fe
Dobereiner's Triads refers to an early arrangement of elements in which J.W. Dobereiner arranged them by their atomic mass in groups of three.
Dobereiner's triads are:
- Li, Na, K
- Ca, Sr, Ba
- Cl, Br, I
- S, Se, Te
- C, N, O
Dobereiner's triads were not applicable to all set of elements. The triad could be made only for few elements. So they were rejected.
The scientist who arranged the elements into triads was Dobereiner.
Triads literally means 'a group of three'. Could be the grouping of CRT phosphor dots, of a book series, and so on. It is an ancient and obvious concept.
atomic mass, triads, and octaves
triads
New land law
Dobereiner's triads were not applicable to all set of elements. The triad could be made only for few elements. So they were rejected.
no.
The merit of Dobereiner's Law of Triads is that it recognized patterns in chemical properties of certain elements and grouped them together based on similarities. However, a major demerit is that it was limited in its application and only applied to a few elements, making it less useful as more elements were discovered that did not fit into triads.
the main defect of' dobereiner's triads is that he put the chemically dissimilar elements in the same triads (dahal.ramchandra@gmail.com)
The scientist who arranged the elements into triads was Dobereiner.
The two most common triads are the Major and the minor triad. The other two types of triads are diminished and augmented triads.
a note
Johann Wolfgang Dobereiner,a German chemist arranged atom in the form of triads in 1817.
A classical accompaniment style based on triads.
Merits and de merits of chemical fertilizer?
Polychord