HISTORY OF PERIODIC SYSTEM

A. Rules triads (Deboreiner)

Three elements with similar chemical properties are grouped together, which is the mass number (NM) elements in the middle is the average of the other two elements

B. Law of octaves (Newlands)

If the elements arranged according to rising numbers of mass number (NM), then the nature of the chemical elements will be repeated on the 8th

C. The long form of periodic system (Mendeleyev)

Periodic system is based on the increase of BA

D. Modern periodic system (Moseley)

Periodic system is based on the atomic number increases (NA).