Changes

[[Chlorine]] is a pale green [[gas]].

==Key Stage 3==

===Meaning===

[[Chlorine]] is a [[Group 7]] [[element]], on the [[Periodic Table]], with an [[Atomic Number|atomic number]] of 17.

===About Chlorine===

: [[Chlorine]] as 17 [[proton]]s and 18 [[neutron]]s in its [[Atomic Nucleus|nucleus]] giving it an [[Atomic Number]] of 17 and an [[Relative Atomic Mass|atomic mass]] of 35.

: An [[atom]] of [[Chlorine]] is missing one [[electron]] from having a full [[Outer Shell|outer shell]].

====Properties====

: [[Chlorine]] is a more [[Reactivity|reactive]] [[Halogen]] than [[Bromine]] but less [[Reactivity|reactive]] than [[Fluorine]].

: [[Chlorine]] [[Chemical Reaction|reacts]] strongly with [[Hydrogen]] to produce [[Hydrogen Chloride]] which [[dissolve]]s in [[water]] to produce [[Hydrochloric Acid]].

: [[Chlorine]] kills [[bacteria]].

: [[Chlorine]] is a pale green coloured [[gas]] at [[STP|room temperature]].

==Key Stage 4==

===Meaning===

===About Chlorine===

====Molecular Structure====

: [[Chlorine]] has the [[Chemical Formula|chemical formula]] [[Chlorine|Cl₂]].

====Atomic Structure====

: There are two [[Stable Isotope|stable isotopes]] of [[Chlorine]], one with 18 [[neutron]]s and the other with 20 [[neutron]]s. They occur in a [[ratio]] of roughly 3:1 so the [[Relative Atomic Mass|atomic mass]] of [[Chlorine]] is 35.5.

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: An [[atom]] of [[Chlorine]] is missing one [[electron]] from having a full [[Outer Shell|outer shell]].

====Properties====

: [[Chlorine]] is a more [[Reactivity|reactive]] [[Halogen]] than [[Bromine]] but less [[Reactivity|reactive]] than [[Fluorine]].

: [[Chlorine]] [[Chemical Reaction|reacts]] strongly with [[Hydrogen]] to produce [[Hydrogen Chloride]] which [[dissolve]]s in [[water]] to produce [[Hydrochloric Acid]].

#Place a piece of [[Litmus Paper|litmus paper]] over the mouth of the [[Test Tube|test tube]].

#If the [[Litmus Paper|litmus paper]] is [[bleach]]ed white then the [[gas]] is [[Chlorine]] or [[Fluorine]].