IGCSE+Atomic+Physics

1.What charge does a neutron have? 1 2.What is the mass of an electron? 1/2000 3.What is another name for proton number? Atomic number 4. What does the atomic mass mean? The relative atomic mass is a measure of the mass of one atom of the element. The ratio of the average mass per atom of the naturally occurring form of an element to one-twelfth the mass of an atom of carbon-12. How small is an atom from TED Ed youtube.com


 * __5.2 Radioactivity __**

5.2.1 Detection of radioactivity • Demonstrate understanding of background radiation Half of background radiation on Earth is naturally radioactive gases in the atmosphere. Some of it comes from natural sources and some comes from artificial sources. Radon is produced in decay(break up) of Uranium ore. [|Background radiation] from BBC GCSE Bitesize Background radiation comes from: •Cosmic rays from space •Radioactive rocks in the ground •Nuclear tests / accidents / bombs

• Describe the detection of α-particles, β-particles and γ-rays (β+ are not included: β-particles will be taken to refer to β–) For the detection of alphas, betas and gammas, a Geiger-Müller counter is used from www.darvill.clara.net [|Penetrating properties of radiation] from BBC GCSE Bitesize [|Penetrating properties of radiation] from unitednuclear.com

5.2.2 Characteristics of the three kinds of emission Radioactive emissions occur __r__ __ andomly __ and __ spontaneously __ over space and time. Radioactivity (a radioactive emission) is a process in which atoms with unstable nuclei spontaneously ( We cannot tell which atoms will go decay the next) __d ecay __. The end result of radioactive decay is the creation of a stable atomic nucleus.

Radioactive decay ( break up, disintegration ) : The spontaneous breakdown of a radioactive nucleus into a lighter nucleus. Radioactive decay causes the release of radiation (energy) in the form of alpha particles, beta particles, or gamma rays. [3]

A diffusion type cloud chamber shows a particle tracks and its ionising effects. A spark counter.

• Discuss the random nature of radioactive emission • Identify α, β and γ-emissions by recalling – their nature – their relative ionising effects – their relative penetrating abilities (β+ are not included: β-particles will be taken to refer to β–)

[|Table of the Properties of the three types of radioactive emission and symbols] from [|docbrown.info] [|Types of radiation] from BBC GCSE Bitesize

The penetrating power of [|α, β and γ radiation] from hyperphysics

• Interpret their relative ionising effects All of alpha, beta, gamma radiations are energetic enough to pull electrons away from atoms. The atoms that have lost electrons are charged particles of **ions**, and hence the name **ionising radiation.** [|Effect of ionising on tissues] from s-cool.co.uk

Ionizing radiation can break chemical bonds and easily make chemical reactions in living cells. [|Ionisation ability] from BBC GCSE Bitesize

[|Alpha] and [|beta decay] from phet • Give and explain examples of practical applications of α, β and γ-emissions [|Uses of alpha beta gamma radiation] from www.passmyexams.co.uk Find a good video clip showing the application of alpha ( α ) and gamma ( γ ) emissions
 * media type="custom" key="29481775" || media type="custom" key="29481779" ||
 * media type="youtube" key="w0_VZuC4nfc" width="560" height="315" ||
 * [| applications of α, β and γ] ||

• Describe their deflection in electric fields and magnetic fields Diagrams of [|deflection in magnetic fields and electric fields] from hyperphysics

[|Deflecting radiation] from BBC GCSE Bitesize

5.2.3 Radioactive decay • State the meaning of radioactive decay • State that during using a- or  b- decay the nucleus changes to that of a different element It is a process in which atoms with unstable nuclei spontaneously decay emitting subatomic particles and energy as they reconfigure into more stable forms.
 * Radioactivity**: The emission of ** radiation ** by unstable atomic nuclei undergoing ** radioactive decay **.


 * Decay**:** 1. ** a spontaneous transformation of an elementary particle into two or more different particles ** 2. ** of an excited atom or molecule, losing energy by the spontaneous emission of photons

**Radioactive decay**: The spontaneous transformation of an unstable atomic nucleus into a lighter one, in which radiation is released in the form of alpha particles, beta particles, gamma rays, and other particles. The rate of decay of radioactive substances such as carbon 14 or uranium is measured in terms of their ** half-life **. • Use equations involving nuclide notation to represent changes in the composition of the nucleus when particles are emitted [|Nuclear equations] from BBC GCSE Bitesize [|Uranium 238 decay chain] from www.unitednuclear.com
 * Supplement **

5.2.4 Half-life • Use the term half-life in simple calculations, which might involve information in tables or decay curves • Calculate half-life from data or decay curves from which background radiation has not been subtracted The HALF-LIFE of an atom is the __ time taken __ for HALF of the radioisotopes in a sample to decay. The decay of radioisotopes can be used to measure the material’s age.
 * Supplement **

The half-life of radioisotopes varies from seconds to billions of years. from [|ndt-ed.org] media type="youtube" key="iuNcgLRufFc" width="560" height="315" [|Science in Focus Radioactivity] S100LS05 [|Lammas Science] Published on 15 Nov 2012 Tasks: 1. Complete the table showing properties of 3 types of radioative emission. 2. Construct three questions while you are watching the video clip. 3. Find the answers to your questions by watching the video clip a second time. 4. Define half-life. [|Half life] from BBC GCSE Bitesize [|Half lives of various elements] from no-nukes.org

**Experiment** (Radioactivity / Half life )
Aim: To simulate decay by rolling die and to estimate the decay constant and half-life from the decay curve. <span style="font-family: 'Times New Roman,Bold'; font-size: 14.6667px;">Apparatus: 100 six sided die.

<span style="font-family: 'Times New Roman,Bold'; font-size: 14.6667px;">Instructions: > remain from the original batch. > sample (as a function of time).
 * 1) Count and record the total number of die. Each dice must have the same number of sides (for our experiment we will use six-sided dice.)
 * 2) Roll all the die at the same time onto a level table. A plastic container can be used to hold all the dice so they can be easily rolled simultaneously. The table should have some friction so that the dice don't slide off the edge. If some of the dice stack up, gently nudge the table so they all lay down flat on the surface.
 * 3) Remove all the dice which turn up "1".
 * 4) Count and record the number removed.
 * 5) Repeat the experiment with the remaining die.
 * 6) Record the time interval between each roll as one second and continue the experiment until no dice
 * 1) Plot the decay curves using total number of dice (as a function of time) as well as the activity of the
 * 1) Estimate the decay constant and half-life from the sample.
 * 2) Repeat steps 2-8 except remove all the dice which turn up "1" or "2".
 * 3) Interpret the value of the decay constant you find from the graphs, is it what you could have expected?
 * 4) Include your graphs and data tables along with your report.

<span style="font-family: 'Times New Roman,Bold'; font-size: 14.6667px;">Reference:
 * Giancoli, 6th Edition Physics

<span style="font-family: 'Times New Roman,Bold'; font-size: 14.6667px;">Assessment Criteria:
 * Time: 1.0 hrs.

<span style="font-family: 'Times New Roman,Bold'; font-size: 14.6667px;">Due Dates: 13th December 2013

5.2.5 Safety precautions • __ Recall [|the effects of ionising radiations on living things] __ from BBC GCSE Bitesize • Describe how radioactive materials are handled, used and stored in a safe way

[|Radioactive Waste Management] from world-nuclear.org After a fuel can has been in a reactor for three or four years, it must be removed and replaced. The amount of uranium-235 in it has fallen and radioactive products are building up. Some are very dangerous: Waste from a nuclear reactor is taken to a reprocessing plant. Remaining waste will be stored with thick shielding around it. Some of the isotopes have long half-lives, so safe storage will be needed for thousands of years.
 * Strontium-90 and iodine-131 are easily absorbed by the body. Strontium becomes concentrated in the bones; iodine in the thyroid gland.
 * Plutonium-239 can be used as a nuclear fuel and in nuclear weapons. It is highly toxic. Breathed in as dust, the smallest amount can kill.

__//Fill in the blanks below.//__
 * Nuclear energy** is a__ non-renewable __ energy resource. In nuclear power station, the __ chain __ reaction inside the reactor creates heat, which heats and turns water into __ steam __ to rotate __ turbines __, which drive generators to produce electricity. The nuclear fuel is safe to handle before they go to reactor. It needs to be handled by robot arms and heavy shielding for safety when they come out from the reactor. Nuclear power stations do not create atmospheric pollution but the small amount of __ waste __ produced is very dangerous. It must be sealed up and buried for many years to allow the __ radioactivity __ to die away. Nuclear power is reliable but a lot of money should spend on safety.

Go visit[| radioactivity] from www.darvill.clara.net


 * __<span style="color: #0070c0; font-family: 'UniversLT-Light','sans-serif'; font-size: 16px;">5.1 The nuclear atom __**

5.1.1 Atomic model • Describe the structure of an atom in terms of a positive nucleus andnegative electrons Image of [|atomic structure] from http://www.docbrown || || • Describe how the scattering of α-particles by thin metal foils provides evidence for the nuclear atom Images from [|chemeddl.org] || Conclusion from Rutherford scattering experiment: Atom must have a dense positively charged region containing most of the atomic mass. ||
 * [[image:Atomic structure.jpg width="500" height="257"]]
 * Supplement **
 * [[image:Schematic diagram of apparatus used by Geiger and Marsden.jpg width="416" height="322"]]
 * Schematic diagram of apparatus used by Geiger and Marsden**

Development of atom model from Cambridgephysics
Rutherford scattering experiment applet from Florida state university =[|Rutherford Scattering Questions from Hyperphysics]= [|Rutherford scattering simulation] Phet media type="custom" key="29481801" [|Rutherford experiment from cyberphysics.co.uk]
 * 1. [|Why was the observation of large angle scattering of alpha particles surprising?] ||
 * 2. [|Under what conditions can you get scattering at angles greater than 90 degrees?] ||
 * 3.[| Besides the mass of the target, what else determines the scattering angle?] ||
 * 4. [|How can you determine the distance of closest approach to the target?] ||
 * 5. [|What was the evidence of a new type of force from the observation of the scattering?] ||

5.1.2 Nucleus • Describe the composition of the nucleus in terms of protons and neutrons • State the charges of protons and neutrons • Use the term proton number Z • Use the term nucleon number A  • Use the term nuclide and use the nuclide notation Z A X

**proton**: A p__ ositively __ charged elementary particle, found in atomic __ nuclei __ in numbers equal to the __ atomic __ number of the element. **neutron:** Neutral, same m __ ass __ as proton **electron:** A n __ egatively __ charged elementary particle in an atom**.** **nucleon**: A __p__ __ roton __ or a __n__ __ eutron __ __,__ especially as part of an atomic nucleus **nuclide**: An atomic nucleus identified by its atomic element and its mass number. For example, a carbon-14 nuclide is the nucleus of a carbon atom, which has six protons, with mass number 14 (thus having eight neutrons). ex) Nucleus is a generic term of nuclide. If nucleus is a country then nuclide is like China. There are about 3000 nuclides.

• Use and explain the term isotope • Balance equations involving nuclide notation An isotope is an atom with a different number of neutrons. e.g. O 16, O 17 , O 18 Radioisotope: An isotope that is radioactive.
 * Sup **** plement **

[|BBC Higher Bitesize] [|Radiation and cancer] from www.cancer.org


 * • State the meaning of nuclear fission and nuclear fusion **

Nuclear fission
Highly unstable nucleus splits into two lighter nuclei, it releases energy while shooting out two or three neutrons. The splitting of the nucleus is called fission. {Natural uranium is a dense radioactive metal. It is mostly made up of two isotopes: uranium-238(over 99%) and uranium-235(less than 1%).} <span style="background-image: url(">nuclear fission from cyberphysics.co.uk Image from [|www.nuclear-power.net] [|Facts about fission products] from Hyperphysics

** Nuclear Fusion ** <span style="background-color: #ffffff; color: #333333; font-family: verdana,helvetica,arial,sans-serif; font-size: 12.6464px;">Two atomic nuclei joining to make a large nucleus. Energy is released during the process of Nuclear fusion so it can also be used as a source of energy. media type="youtube" key="Ux33-5k8cjg" width="560" height="315" [|Where Does The Sun Get Its Energy]? [|Veritasium] Published on 6 May 2012 Image from [|nuclear-energy.net] Have you spotted the Earth in the solar system? Can you describe nuclear fusion? How does fusion power the Sun?
 * [|How close are we to nuclear fusion] from forbes.com **
 * [|What is nuclear fusion] ** from www.iter.org

<span style="background-image: url(">[|Nuclear fission and fusion] from BBC Bitesize [|Nuclear fusion getting closer] from science.howstuffworks.com <span style="background-image: url(">[|Atomic physics revision] from schoolphysics.co.uk

[|Neutrino] from Britannica media type="youtube" key="O5iaw5WNuB0" width="560" height="315" [|Parts of an atom song] by Mr. Parr Youtube
 * Interesting subatomic particle - Further reading if interested**