PERIODIC TABLE OF ELEMENT

PERIODIC TABLE OF ELEMENT

(Article = http://en.wikipedia.org/wiki/Periodic_table)



The periodic table of the chemical elements (also periodic table of the elements or just periodic table) is a tabular display of the chemical elements. Although precursors to this table exist, its invention is generally credited to Russian chemist Dmitri Mendeleev in 1869, who intended the table to illustrate recurring ("periodic") trends in the properties of the elements. The layout of the table has been refined and extended over time, as new elements have been discovered, and new theoretical models have been developed to explain chemical behavior.

The periodic table is now ubiquitous within the academic discipline of chemistry, providing a useful framework to classify, systematize, and compare all of the many different forms of chemical behavior. The table has found many applications in chemistry, physics, biology, and engineering, especially chemical engineering. The current standard table contains 118 elements as of March 2010 (elements 1–118).


Element categories in the periodic table

Metals Metalloids Nonmetals Unknown chemical properties Alkali metals Alkaline earth metals Inner transition elements Transition elements Other metals Other nonmetals Halogens Noble gases Lanthanides Actinides
Atomic number colors show state at standard temperature and pressure (0 °C and 1 atm) Solids Liquids Gases Unknown	Borders show natural occurrence Primordial From decay Synthetic (Undiscovered)