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===About Groups===
: [[Helium]], in [[Group 0]] is an exception to this rule as it has 2 [[electron]]s in its [[Outer Shell]].
: The [[element]]s are arranged '''groups''' of similar [[Chemical Property|chemical properties]].
: [[Element]]s have similar [[Chemical Property|chemical properties]] when they have the same number of [[electron]]s in the [[Outer Shell]].
|[[File:PeriodicTableGroups.png|center|600px]]
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The [[Chemical Property|chemical properties]] of [[element]]s within a '''group''' are similar. However, the [[reactivity]] within a '''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'''.
The [[Physical Property|physical properties]] of [[element]]s within a '''group''' are similar. However, the property changes gradually as you move down the '''group'''.
==Key Stage 4==
===Meaning===
A '''Group''' is a column on the [[Periodic Table]] with [[element]]s with the same number of [[electron]]s on the [[Outer Shell]].
===About Groups===
: [[Helium]], in [[Group 0]] is an exception to this rule as it has 2 [[electron]]s in its [[Outer Shell]].
: The [[element]]s were oringally arranged '''groups''' of similar [[Chemical Property|chemical properties]].
: It was later discovered that [[element]]s have similar [[Chemical Property|chemical properties]] when they have the same number of [[electron]]s in their [[Outer Shell]]s.
{| class="wikitable"
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|[[File:PeriodicTableGroups.png|center|600px]]
|}
===Trends within groups===
The [[Chemical Property|chemical properties]] of [[element]]s within a '''group''' are similar. However, the [[reactivity]] within a '''group''' changes as you move up or down the [[Period (Chemistry)|period]]s due to the number of [[Electron Shell]]s.
====[[Group 1]]: The [[Alkali Metal]]====
=====Chemical Properties=====
: '''Alkali Metals''' are all highly [[Reactivity|reactive]] and will [[Oxidisation|oxidise]] quickly in the presence of [[Oxygen]].
: '''Alkali Metals''' all [[Chemical Reaction|react]] strongly with [[water]] to produce [[Metal Hydroxide|metal hydroxides]] and [[Hydrogen]] [[gas]].
: '''Alkali Metals''' all produce strong [[alkali]]s.
{| class="wikitable"
|-
|[[File:Group1ElectronShells.png|center|100px]]
| style="height:20px; width:500px; text-align:left;" |In a [[Chemical Reaction|chemical reaction]] the [[electron]] in the [[Outer Shell|outer shell]] is lost.
The [[reactivity]] increases as you go down the group because:
*The outer [[electron]] is further away from the [[Atomic Nucleus|nucleus]] with each additional [[Electron Orbital|electron shell]] making the [[force]] of [[attract]]ion weaker. This makes it easier for an [[atom]] to lose it's outer [[electron]].
*Even though the [[charge]] of the [[Atomic Nucleus|nucleus]] increases the outer [[electron]] is shielded from most of the [[Positive Charge|positive charge]] of the [[Atomic Nucleus|nucleus]] by [[electron]]s in the [[Inner Shell|inner shells]].
|}
=====Physical Properties=====
: '''Alkali Metals''' have a low [[density]] compared to other [[metal]]s.
: '''Alkali Metals''' are all [[solid]] at [[Room Temperature|room temperature]] but have a low [[Melting Point|melting point]] compared to other [[metal]]s.
: '''Alkali Metals''' are soft and can be easily cut.
: '''Alkali Metals''' all appear shiny (before they [[oxidisation|oxidise]]).
*[[Group 2]]: The [[Alkali Earth Metal]]s all react strongly with steam and acids. The [[reactivity]] increases as you go down the '''group'''.
*[[Group 7]]: The [[Halogen]]s all act as bleaching agents and kill bacteria. The reactivity decreases as you go down the '''group'''.
*[[Group 0]]: The [[Noble Gases]] are all inert (unreactive).