About Dmitri Mendeleeve

"If all the elements are arranged in the order of their atomic weights, a periodic repetition of properties is obtained. This is expressed by the law of periodicity."
Dmitri Mendeleev, Principles of Chemistry, Vol. 2, 1902, P. F. Collier, p17.

How the Periodic Table was influenced by Dmitri Mendeleev

The periodic table that we use today was greatly influenced by Dmitri Mendeleev in 1869.

Mendeleev arranged the 65 elements to a grid or table so that each element had the following:

1. A higher atomic weight than the one on its left. For example, magnesium (atomic weight 24.3) is placed to the right of sodium (atomic weight 23.0):


2. Similar chemical properties to other elements in the same column - in other words similar chemical reactions. Magnesium, for example, is placed in the alkali earths' column:


Mendeleev realized that the table could be the foundation of chemistry. Mendeleev also realized that his table was incomplete.

Mendeleev discovered the element eka-silicon, after observing a hole in the periodic table between silicon and tin:


Mendeleev also discovered gallium (eka-aluminum) and scandium (eka-boron), because he predicted their existence and their properties before they actually happened..