The Periodic Table

What is Dimitri Mendeleev's Periodic Table of Elements and Atomic Numbers

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What is the element The Periodic Table based on the IOUPAC 1985 standard
Click on an Element in the Periodic Table - More Information will be displayed under the table

Properties within each individual group are similar, but nevertheless vary within a group. Generally chemical activity decreases as the period increases a non-metal group and increases as the period increases within a metal group.

The first element in a group is always an active metal, the last is always an inactive non-metal.


The period of an element signifies the highest energy level an electron in that element occupies in an unexcited state. Generally, within a given period, the chemical activity of metals increases with the group number , while the chemical activity of non-metals within a given period decreases with the group number.

Dimitri Mendeleev and the first Periodic Table
Dimitri Mendeleev was born on February 7th 1834 in Tobolsk, a Town in Siberia. In 1869 at the age of 35 the famous Russian Scientist perceived a totally new classification Method "the periodic table", he included all the 65 elements known in his time by their atomic weights and chemical valency.


The Modern Periodic Table
Fifty years after Dimitri Mendeleev created the Periodic cable, the British scientist Henry Moseley discovered that the number of protons in the nucleus of a particular type of atom was always the same. When atoms are arranged via their atomic number, the few remaining problems with Mendeleev's original periodic table disappeared. Due to Moseley's work, the modern periodic table is based on the atomic numbers of the elements rather than atomic mass.

For additional information about the elements featured on the Periodic Table please refer to our comprehensive Elements Map!

Dimitri Mendeleev and The Periodic Table

The Elements are the building blocks of Modern Science & Chemistry
for a chart that details the weights click
Periodic Table with Atomic Mass


Information - Periodic Table - Elements - Info - Atomic Number - Atomic Weight - Tables - Period - Mass - Online - Science - Quiz - Information - Periodic Table - Elements - Info - Atomic Number - Atomic Weight - Melting Point - Boiling Point - Tables - Period - Mass - Online - Science - Quiz - Written By Linda Alchin