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===About The Periodic Table===
: The modern [[Periodic Table]] was arranged by a scientist called [[Mendeleev]]. Others had tried to arrange all the [[element]]s before, but [[Mendeleev]] was the first to arrange by both [[Atomic Number]] and [[Chemical Property|chemical properties]].
: The columns of the [[Periodic Table]] are called [[Group(Chemistry)|group]]s.
: The rows of the [[Periodic Table]] are called [[Period (Chemistry)|Period]]s.
===Groups===
: The [[element]]s are arranged [[Group (Chemistry)|group]]s of similar [[Chemical PropertiesProperty|chemical properties]].: [[Element]]s have similar [[Chemical PropertiesProperty|chemical properties]] when they have the same number of [[electron]]s in the [[Outer Shell]].
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====Trends within groups====
The [[Chemical Property|chemical properties]] of [[element]]s within a [[Group (Chemistry)|group]] are similar. However, the [[reactivity]] within a [[Group (Chemistry)|group]] changes as you move up or down the [[Period (Chemistry)|period]]s.*[[Group 1]]: The [[Alkali Metal]]s all react strongly with water. The [[reactivity]] increases as you go down the [[Group (Chemistry)|group]].*[[Group 2]]: The [[Alkali Earth Metal]]s all react strongly with steam and acids. The [[reactivity]] increases as you go down the [[Group (Chemistry)|group]].*[[Group 7]]: The [[Halogen]]s all act as bleaching agents and kill bacteria. The reactivity decreases as you go down the [[Group (Chemistry)|group]].
*[[Group 0]]: The [[Noble Gases]] are all inert (unreactive).
The [[Physical Property|physical properties]] of [[element]]s within a [[Group (Chemistry)|group]] are similar. However, the property changes gradually as you move down the [[Group (Chemistry)|group]].
===Periods===