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:[https://www.amazon.co.uk/gp/product/1782945695/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1782945695&linkCode=as2&tag=nrjc-21&linkId=ceafcc80bcad6b6754ee97a0c7ceea53 ''Alpha radiation, pages 197, 198, 200, Gateway GCSE Combined Science; The Revision Guide, CGP, OCR '']
:[https://www.amazon.co.uk/gp/product/1782945687/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1782945687&linkCode=as2&tag=nrjc-21&linkId=9a598e52189317a20311d7a632747bc9 ''Alpha radiation, pages 74-76, 78, 79, Gateway GCSE Physics; The Revision Guide, CGP, OCR '']
==Key Stage 5==
===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 when a [[Atomic Nucleus|nucleus]] is too large or the [[ratio]] of [[proton]]s to [[neutron]]s is too large.
: '''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"
|-
|[[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 an [[Alpha Particle|α-particle]] by sending it between two [[Electrical Charge|electrically charged]] plates and observing its path.
The '''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 15cm 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|600px]]
|-
| style="height:20px; width:600px; text-align:left;" |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]].
: [[Alpha Particle|Alpha]] sources are kept inside a block of [[lead]] with a hole that only allows the [[Alpha Particle|alpha particles]] out in one direction.
: 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.
: Inside an [[organism]] [[Alpha Particle|alpha particle]]s are the most dangerous as they are highly [[Ionising Radiation|ionising]] and there is nothing inside an [[organism]] to block them [[Ionising Radiation|ionising]] biological [[molecule]]s like [[DNA]]. Every precaution must be taken not to [[Radioactive Contamination|contaminate]] the skin with the [[Alpha Particle|alpha]] source in case it finds its way into the body through a cut or the mouth.
: When handling a source of [[Alpha Particle|alpha radiation]] the precautions which should be taken are:
:*Wear gloves - to prevent [[Radioactive Contamination|contamination]].
:*Use tongs more than 5cm long to handle the source, never touch it - to prevent [[Radioactive Contamination|contamination]] and [[irradiation]].
:*Aim the source away from any living [[organism]] - to prevent [[irradiation]].
:*Store the source in a sealed container - to prevent [[Radioactive Contamination|contamination]] and [[irradiation]].
===Applications===
{| class="wikitable"
|-
|[[File:SmokeDetector.png|center|600px]]
|-
| style="height:20px; width:600px; text-align:left;" |In a smoke detector [[Alpha Particle|alpha particles]] are released between two [[electrode]]s.
When the [[Alpha Particle|alpha particles]] [[Ionising Radiation|ionise]] the [[molecule]]s in the [[air]] the [[ion]]s move between the [[electrode]]s and a [[Electrical Current|current]] flows in the [[circuit]].
When smoke gets between the [[electrode]]s the [[ion]]s become stuck in large [[particle]]s of [[soot]] preventing them from moving. This stops the [[Electrical Current|current]] in the [[circuit]].
The [[ammeter]] in the [[circuit]] is connected to an alarm which goes off when there is no [[Electrical Current|current]].
|}
===Equation===
<math>_Z^AX \rightarrow _{Z-2}^{A-4}Y + _2^4\alpha</math>
<math>_{92}^{238}U \rightarrow _{90}^{234}Th + _2^4\alpha</math>
====Example Calculations====
{| class="wikitable"
|-
| style="height:20px; width:300px; text-align:center;" |'''Find the [[element]] 'X' and calculate its [[Relative Atomic Mass|relative atomic mass]] 'A' and its [[Relative Atomic Charge|relative atomic charge]] 'Z'.'''
<math>{}_{84}^{210}Po \rightarrow {}_{Z}^{A}X + {}_2^4\alpha</math>
| style="height:20px; width:300px; text-align:center;" |'''Find the [[element]] 'X' and calculate its [[Relative Atomic Mass|relative atomic mass]] 'A' and its [[Relative Atomic Charge|relative atomic charge]] 'Z'.'''
<math>{}_{Z}^{A}X \rightarrow {}_{86}^{222}Rn + {}_2^4\alpha</math>
|-
| style="height:20px; width:300px; text-align:left;" |'''1. Calculate the [[Relative Atomic Mass|relative atomic mass]] by looking at the top row of numbers.'''
210 = A + 4
A = 206
| style="height:20px; width:300px; text-align:left;" |'''1. Calculate the [[Relative Atomic Mass|relative atomic mass]] by looking at the top row of numbers.'''
A = 222 + 4
A = 226
|-
| style="height:20px; width:300px; text-align:left;" |'''2. Calculate the [[Relative Atomic Charge|relative atomic charge]] by looking at the bottom row of numbers.'''
84 = Z + 2
Z = 82
| style="height:20px; width:300px; text-align:left;" |'''2. Calculate the [[Relative Atomic Charge|relative atomic charge]] by looking at the bottom row of numbers.'''
Z = 86 + 2
Z = 88
|-
| style="height:20px; width:300px; text-align:left;" |'''3. Since the [[Relative Atomic Charge|relative atomic charge]] is the same as the [[Atomic Number|atomic number]] look up the [[element]] on the [[Periodic Table|periodic table]].'''
<math>{}_{82}^{206}Pb</math>
| style="height:20px; width:300px; text-align:left;" |'''3. Since the [[Relative Atomic Charge|relative atomic charge]] is the same as the [[Atomic Number|atomic number]] look up the [[element]] on the [[Periodic Table|periodic table]].'''
<math>{}_{88}^{226}Ra</math>
|}