Atom has a very small mass. The method of determining the relative atomic mass stated by Berzelius (1814) from Sweden and P. Dulong and A. Petit (1819), both from France. Berzelius and Dulong and Petit determine the relative atomic mass of the element based on specific heat. The relative atomic mass of an element essential nature and a specific nature, as each element has a specific relative atomic mass different from the other elements.
1.1. Based on metal characteristic, elements divided become metal and nonmetal.
|The elements classified asmetals and as
In 1829, Johan Wolfgang Dobereiner, a professor of chemistry in Germany, suggests that the relative atomic mass of Strontium is very close to the average mass of the two other elements like Litium, Natrium and Kalium that. Dobereiner also found some other elements such groups. Therefore, Dobereiner conclude that the elements can be grouped into groups called “Triade tiga unsur”. But unfortunately, Dobereiner failed to show enough triade so useful rule. Although the idea of Dobereiner not very successful, but it is the first at tempt in the classification of the element. The theory of Dobereiner, example :
Atomic mass in the middle
Atomic mass Na = Atomic mass Li + Atomic mass K
= 6,94 + 39,10 = 23,02
1.3.Newlands law of octaves
In 1864 a British chemist named AR Newlands announced the discovery of the so-called Law of Octaves. Newlands arrange the elements of increasing relative atomic mass. Ex. law of octaves Newland is as follows: