Periodic table of elements

Periodic Table of Elements

The Periodic Table of Elements is a tabular arrangement of chemical elements, organized based on their atomic number, electron configuration, and recurring chemical properties. Elements are listed in order of increasing atomic number, which corresponds to the number of protons in an element's atomic nucleus.

History

The first periodic table was developed in 1869 by Dmitri Mendeleev. Mendeleev's table was similar to the modern periodic table, but it contained gaps and was arranged by atomic weight. The modern periodic table is based on the Moseley's Law, which was discovered by Henry Moseley in 1913.

Structure

The periodic table is divided into several blocks:

• The s-block includes the first two groups: alkali metals and alkaline earth metals, as well as hydrogen and helium.
• The p-block includes the last six groups, which are groups 13 to 18.
• The d-block includes transition metals.
• The f-block includes the lanthanides and actinides.

Periods and Groups

The periodic table is organized into seven horizontal rows, or periods, and 18 vertical columns, or groups.

Chemical Series

Elements in the same group of the periodic table are often categorized into chemical series. Some of these series include the Noble gases, Alkali metals, Alkaline earth metals, Transition metals, Post-transition metals, Metalloids, Polyatomic nonmetals, Diatomic nonmetals, and Halogens.

See Also

• History of the periodic table
• Electron configuration
• Chemical element
• Atomic number

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