HOW DID THE CONCEPT OF ATOMIC NUMBER LEAD TO THE SYNTHESIS OF

NEW ELEMENTS IN THE LABORATORY?

Chemists in 19th century generally agreed about what particles consisted matter and agreed that matter consisted of atoms. However, they knew nothing about the structure of the atoms.

The information about the known elements gave them inspiration to arrange the elements in a table.

JOHN ALEXANDRIA REINA NEWLANDS

In 1864, J.A.R Newlands, an English chemist noticed that when the elements were arranged according to increasing mass, every eighth element would exhibit similar properties, better known as the Law of Octaves.

Li Be B C N O F Na Mg Al

7 9 11 12 14 16 19 23 24 27

Si P S Cl K Ca

28 31 32 35.5 39 40

ARRANGEMENT OF ELEMENTS ACCORDING TO NEWLANDS

DMITRI IVANOVICH MENDELEEV

A Russian chemist who developed the periodic classification of the elements. Mendeleev found that, when all the known chemical elements were arranged in order of increasing atomic weight, the resulting table displayed a recurring pattern, or periodicity, of properties within groups of elements.

JULIUS LOTHAR MEYER

A German chemist who also worked on a periodic table. Meyer’s table only included twenty-eight elements, which were not classified by atomic weight, but by valence.

This periodic table, although remarkably successful, had some inconsistencies.

HENRY GWYN JEFFRIEYS MOSELEY

English physicist who experimentally demonstrated that the major properties of an element are determined by the atomic number, not by the atomic weight, and firmly established the relationship between atomic number and the charge of the atomic nucleus.

When Moseley arranged the elements in the periodic table by their number of protons rather than their atomic weights, the flaws in the periodic table that had been making scientists uncomfortable for decades simply disappeared.