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==Key Stage 4==
===Meaning===
An '''alpha particle''' ('''α-particle''') is a type of [[Ionising Radiation|ionising radiation]] made of 2 [[proton]]s and 2 [[neutron]]s [[emit]]ted from the [[Atomic Nucleus|nucleus]] of an [[Unstable Isotope|unstable isotope]].
===About Alpha Particles===
: '''Alpha particles''' may also be referred to as '''alpha radiation''' and is written with the symbol '''α'''.
: '''Alpha particles''' are a [[Helium]] [[Atomic Nucleus|nucleus]].
: '''Alpha particles''' have a [[Relative Atomic Mass|relative atomic mass]] of 4 and [[Relative Atomic Charge|relative charge]] of +2.
: '''Alpha particles''' are [[emit]]ted rather than single [[proton]]s or [[neutron]]s because the [[Helium]] [[Atomic Nucleus|nucleus]] is extremely [[Stable Isotope|stable]].
====Charge and Mass====
{| class="wikitable"
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|[[File:AlphaParticleCharge.png|center|200px]]
| style="height:20px; width:400px; text-align:left;" |Scientist were able to determine the [[Electrical Charge|charge]] and [[mass]] of [[Alpha Particle|alpha α-particle]] by sending it between two [[Electrical Charge|electrically charged]] plates and observing its path.
The '''alpha α-particle''' moves towards the [[Negative Charge|negative]] plate, so it must be [[Positive Charge|positively charged]]. The rate of curvature depends on the [[mass]]:[[Electrical Charge|charge]] [[ratio]] which indicates it has a [[Relative Atomic Mass|relative atomic mass]] of 4 and [[Relative Atomic Charge|relative charge]] of +2.
|}
====Penetration Depth====
{| class="wikitable"
|-
|[[File:AlphaPenetrationAir.png|center|200px]]
| style="height:20px; width:400px; text-align:left;" |[[Alpha Particle|Alpha particles]] can travel around 5cm through [[air]] ([[STP]]) before [[colliding]] with and [[ionising]] [[atom]]s or [[molecule]]s.
|}
{| class="wikitable"
|-
|[[File:AlphaPenetration.png|center|200px]]
| style="height:20px; width:400px; text-align:left;" |[[Alpha Particle|Alpha particles]] can be stopped by a thin sheet of paper.
|}
===Ionising Potential===
: With a [[Electrical Charge|charge]] of +2, '''α-particles''' are the most [[Ionising Radiation|ionising]] of the three [[Ionising Radiation|ionising radiations]]. It is capable of removing two [[electron]]s from a single [[atom]] or [[molecule]] or removing 1 [[electron]] from two [[atom]]s or [[molecule]]s.
{| class="wikitable"
|-
|[[File:AlphaIonise.png|center|500px]]
|-
| style="height:20px; width:500px; text-align:center;" |When an [[Alpha Particle|α-particle]] interacts with an [[atom]] the [[Alpha Particle|α-particle]] can remove one or two [[electron]]s to '''ionise''' the [[atom]].
|}
===Precautions===
: [[Alpha Particle|Alpha radiation]] is the most [[Ionising Radiation|ionising]] but the least [[Penetration Depth|penetrating]].
: Outside the body an [[organism]] can be protected from [[Alpha Particle|alpha radiation]] by keeping a distance greater than 5cm or by covering any bare skin.
: When handling a source of [[Alpha Particle|alpha radiation]] the precautions which should be taken are:
:*Wear gloves
:*Use tongs to handle the source, never touch it.
:*Aim the source away from any living [[organism]].
:*Store the source in a sealed container.