Periodic table

Periodic Table of Elements contains the currently identified chemical elements arranged based on their chemical properties. Elements have certain properties and tendencies to react that were found to repeat periodically when elements of increasing atomic masses were compared.

Each cell of the table contains a different element. The cells of most periodic tables contain the name and symbol of each element, the atomic number (the number of protons), and the atomic weight (average number of protons + neutrons). Some periodic tables will contain other information, such as the electron shell configuration of each element, or their state at room temperature (liquid, gas, or solid).

The electron configurations of atoms is the primarily determinant of their chemical reactivity, and particularly the outer-shell (or "valence") electrons. The elements in the periodic table are arranged into rows (known as groups or families) and columns (known as periods) based on how many shells of electrons the atoms possess, and the number of electron in outer-shell (valence electrons), respectively.

Periodic Table of Elements
Click on the chemical symbols below for more information on a specific element.


 * 1Actinides and lanthanides are collectively known as "Rare Earth Metals".
 * 2Alkali metals, alkaline earth metals, transition metals, actinides, lanthanides, and poor metals are all collectively known as "Metals".
 * 3Halogens and noble gases are also non-metals.

State at standard temperature and pressure
 * those with atomic number in red are gases
 * those with atomic number in blue are liquids
 * those with atomic number in black are solid

Natural occurrence
 * those with solid borders have isotopes that are older than the Earth (Primordial elements)
 * those with dashed borders naturally arise from decay of other chemical elements and have no isotopes older than the earth
 * those with dotted borders are made artificially (Synthetic elements)
 * those without borders have not been discovered yet