Scheme of Work s6

Scheme of work Combined Science: Trilogy Physics – Atomic structure

This resource provides guidance for teaching the Atomic structure topic from our new GCSE in Combined Science: Trilogy/Physics (8464). It has been updated from the draft version to reflect the changes made in the accredited specification such as the specification reference numbers. A few changes have also been made to learning outcomes and the opportunities to develop skills columns.

The scheme of work is designed to be a flexible medium term plan for teaching content and development of the skills that will be assessed. It is provided in Word format to help you create your own teaching plan – you can edit and customise it according to your needs. This scheme of work is not exhaustive; it only suggests activities and resources you could find useful in your teaching.

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6.4.1 Atoms and isotopes

Spec ref. Summary of the Learning outcomes Suggested timing Opportunities to Opportunities to specification content (hours) develop Scientific develop and apply What most candidates Communication skills practical and enquiry should be able to do skills

6.4.1.1 The size and structure of an atom. Atoms are 0.5 How big is an atom? Model an atom using very small, plasticine. On the model What particles are in an atom? having a show where most of the radius of Where is each particle found mass is concentrated and about 1 x 10- within the atom? that most of the atom is 10 metres. empty space. State the size of the atom in The basic standard form. Research how absorption structure of and emission spectra are an atom is a Describe the composition of an formed. positively atom and draw a fully labelled charged diagram of an atom showing nucleus protons and neutrons in the composed of nucleus with electrons outside the both protons nucleus. and neutrons Give the charges of all particles surrounded within the atom. by negatively charged Calculate the size of an atom electrons. given the size of the nucleus and the scale of the nucleus compared The radius of to the atom. a nucleus is less than Describe how the concentration of 1/10,000 of mass of an atom is not uniform the radius of but concentrated on the nucleus an atom. of the atom. Most of the Describe how electrons are mass of an arranged within an atom. atom is concentrated Describe and explain how in the electrons can be moved further nucleus. away from the nucleus of the atom and how they lose energy to move The electrons closer to the nucleus. are arranged at different Explain how the wavelength of the distances electromagnetic wave emitted by from the an electron changes in relation to nucleus how far the electron has moved (different towards the nucleus. energy levels). The electron arrangement s may change with the absorption of

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electromagne tic radiation (move further from the nucleus; a higher energy level) of by the emission of electromagne tic radiation (move closer to the nucleus; a lower energy level). 6.4.1.2 Describing an atom in terms of In an atom 0.5 What is ionisation? Use simple modelling protons, neutrons and electrons. the number techniques to show that How can an atom be ionised? of electrons the number of protons in How to represent atoms. is equal to Why do some elements have an isotope of an element the number isotopes? remains constant but the of protons in number of neutrons the nucleus. Describe the composition of a changes. Atoms have given atom in terms of the number Produce a table showing no overall of protons and electrons. the mass number, atomic electrical Explain why atoms have no number and number of charge. overall electrical charge, as the neutrons for an element All atoms of a number of protons and electrons given in the form . particular is equal. element have Research how atoms can be the same ionised by making the number of number of protons different to the number of protons. The electrons in an atom. number of protons in an State that the number of protons atom of an in a given element is always the element is same, though the mass number called its my change. atomic Define the atomic number for an number. element. The total Calculate the number of neutrons number of for a stated element given the protons and number of protons and the mass neutrons in number. an atom is called its Calculate the mass number for a mass particular element given the number. number of protons and neutrons in the atom. Rearrange the equation Atoms of the to find number of protons or same number of neutrons and the mass

element can number. have different Explain how isotopes of elements, numbers of all have the same number of neutrons. protons but have a different These atoms number of neutrons. are called isotopes of Define isotope. that element. Describe an atom in terms of Atoms can be number of protons, neutrons and represented electrons when given the following as shown in representation . this example:

Atoms turn into positive ions if they lose one or more outer electron(s) 6.4.1.3 Scientific models of the atom and New 0.6 Why has the model of the atom Model the alpha scattering how these models have changed. experimental changed since ancient Greek experiment by flicking a 1p evidence times? coin through stack of 2p may lead to a coins. The 1p coin Describe and explain why scientific represents the alpha scientific models are replaced. model being particle and the stack of changed or Describe why ancient Greeks 2p coins the gold foil. How replaced. thought that the atom could not be must the stacks be divided. arranged in order that Before the 90% of the coins go discovery of Draw a diagram to illustrate the straight through without the electron, ‘plum-pudding model’ of the atom. scattering? What atoms were conclusion can be drawn thought to be Explain why the ‘plum-pudding about the arrangement of tiny spheres model’ was ‘better’ than the Greek atomic nuclei in a material that could not model of the indivisible atom. and the amount of free be divided. Describe the alpha scattering space between nuclei? The experiment What was so amazing discovery of about the alpha scattering the electron experiment? Details of these led to the experiments are not required. ‘plum- pudding Explain how the evidence from the model’ of the scattering experiment led to a atom. The change in the atomic model of the ‘plum- atom. pudding Describe the difference between model’ the ‘plum-pudding model’ of the suggested AQA Education (AQA) is a registered charity (number 1073334) and a company limited by guarantee registered in England and Wales (number 3644723). Our registered address is AQA, Devas Street, Manchester M15 6EX. 4 of 14 Spec ref. Summary of the Learning outcomes Suggested timing Opportunities to Opportunities to specification content (hours) develop Scientific develop and apply What most candidates Communication skills practical and enquiry should be able to do skills

that the atom atom and the nuclear model of the was a ball of atom. positive charge with Produce a timeline to show how negative our ideas about atoms have electrons changed since ancient Greek embedded in times. it. Find out about the origins of the The results words protons, neutrons and from the electrons. alpha scattering experiment led to the conclusion that the mass of an atom was concentrated at the centre (nucleus) and that the nucleus was charged. The alpha scattering experiment led to the ‘plum- pudding model’ being replaced by the nuclear model. Neils Bohr adapted the nuclear model by suggesting that electrons orbit the nucleus at specific distances. Later experiments led to the idea that the positive charge of any

nucleus could be subdivided into a whole number of smaller particles, each particle having the same amount of positive charge. The name ‘proton’ was given to these particles. Lastly, in 1932, the experimental work of James Chadwick provided the evidence to show the existence within the nucleus of the neutron. This was about 20 years after the nucleus became an accepted scientific idea.

AQA Education (AQA) is a registered charity (number 1073334) and a company limited by guarantee registered in England and Wales (number 3644723). Our registered address is AQA, Devas Street, Manchester M15 6EX. 6 of 14 6.4.2 Atoms and radiation

Spec Summary of the specification Learning Suggested timing (hours) Opportunities Opportunities to ref. content outcomes to develop develop and apply Scientific practical and enquiry What most Communication skills candidates skills should be able to do 6.4.2.1 The radioactive decay of an Some atomic 0.4 Why are some Investigate the random unstable element. nuclei are atoms nature of radioactive unstable. The radioactive? decay by throwing dice Activity is measured in Becquerel nucleus gives or coins. Is it possible (Bq). Where does out ionising to predict which dice the radiation radiation as it will land on a six (or come from? changes to coins on a head)? become Describe more stable. radioactive This is a decay as a random process by process which an called unstable atom radioactive releases decay. radiation. Activity is the How does rate at which activity change a source of with time? unstable nuclei decays Research how and is nuclear measured in radiation was Becquerel. discovered and who discovered it. State that the part of the atom, which releases the radiation, is the nucleus. Describe how the emission of radiation from a radioactive atom is a random process, but over time the amount of decay can be predicted. 6.4.2.1 The nature of different types of The nuclear 0.4 Are all Model alpha, beta, nuclear radiation. radiation radioactive gamma and neutron emitted may sources the decay using plasticine be: same? and/or stop frame animation. Models Describe the  an alpha should show the atom composition of particle before and after decay each type of AQA Education (AQA) is a registered charity (number 1073334) and a company limited by guarantee registered in England and Wales (number 3644723). Our registered address is AQA, Devas Street, Manchester M15 6EX. 7 of 14 Spec Summary of the specification Learning Suggested timing (hours) Opportunities Opportunities to ref. content outcomes to develop develop and apply Scientific practical and enquiry What most Communication skills candidates skills should be able to do (α) – this radiation and as well as the radiation consists where relevant, emitted. of two give the particle neutrons that the type of and two radiation is protons, it identical to, eg is an alpha identical particle is a to a helium nucleus. helium Research how nucleus with beta decay  a beta an electron particle happens to be (β) – a in the nucleus. high Describe how speed in beta electron emission a ejected neutron decays from the into a proton nucleus and an as a electron, with neutron the electron turns into then being a proton ejected from  a gamma the nucleus at ray (γ) – high speed. electroma Describe gnetic gamma rays as radiation being part of from the the nucleus. electromagneti c spectrum as  a neutron well as a type (n) of nuclear radiation. Describe how a neutron can be emitted from a nucleus. 6.4.2.1 The penetration of alpha, beta Properties of 0.4 Which type of Demonstrate the and gamma radiation through alpha radiation is the penetration of alpha, different materials. particles, most beta and gamma beta particles dangerous? radiation. Link the and gamma penetration of each Where do rays limited type of radiation to the radioactive to their nature of the radiation sources come penetration and the uses of the from? through radioactive sources. materials and Draw a Plan an experiment to their range in diagram to determine the type of AQA Education (AQA) is a registered charity (number 1073334) and a company limited by guarantee registered in England and Wales (number 3644723). Our registered address is AQA, Devas Street, Manchester M15 6EX. 8 of 14 Spec Summary of the specification Learning Suggested timing (hours) Opportunities Opportunities to ref. content outcomes to develop develop and apply Scientific practical and enquiry What most Communication skills candidates skills should be able to do air. illustrate the radiation emitted by an penetration of unknown radioactive the different source. Produce a risk types of assessment for this nuclear experiment. radiation. Evaluate the use of different shielding materials for use when handling radioactive sources when supplied with relevant data. Explain why gamma sources are usually the most harmful when outside the body and alpha are the most dangerous when inside the body in terms of penetration of the radiation. 6.4.2.2 Nuclear decay equations Nuclear 0.5 How do atoms Model the radioactive equations are change when decay of alpha and used to they undergo beta sources. Use the represent radioactive model to construct radioactive decay? decay equations for decay. alpha and beta decay. Describe what Critically analyse the In a nuclear happens to an limitations of the equation an atom when it models produced by alpha particle undergoes the class. may be alpha, beta and represented gamma by the emission. symbol: Calculate how the mass number, the and a beta proton number particle by and the number the symbol: of neutrons in an atom

AQA Education (AQA) is a registered charity (number 1073334) and a company limited by guarantee registered in England and Wales (number 3644723). Our registered address is AQA, Devas Street, Manchester M15 6EX. 9 of 14 Spec Summary of the specification Learning Suggested timing (hours) Opportunities Opportunities to ref. content outcomes to develop develop and apply Scientific practical and enquiry What most Communication skills candidates skills should be able to do The emission change when it of the undergoes different alpha, beta and types of gamma ionising emission. radiation may State the cause a composition of change in the alpha and beta mass and/or particles and the charge of be able to the nucleus. recall that an For example: alpha particle can be represented as: Alpha decay causes both the mass and and a beta charge of the particle can be nucleus to represented as: decrease.

Complete Beta decay nuclear decay does not calculations for cause the alpha and beta mass of the decay. The nucleus to calculations change, but it may be in the does cause form of an equation or a the charge of table of results the nucleus showing the to increase. same data. The emission Describe in of a gamma words how the ray does not nucleus of an cause the atom changes when it mass or the undergoes charge of the alpha and beta nucleus to decay. change. Describe how the charge of a nucleus changes as it undergoes alpha and beta decay. 6.4.2.3 The randomness of radioactive Radioactive 0.5 How does the Demonstrate the decay. decay is activity of a randomness of the random so it radioactive decay of a radioactive AQA Education (AQA) is a registered charity (number 1073334) and a company limited by guarantee registered in England and Wales (number 3644723). Our registered address is AQA, Devas Street, Manchester M15 6EX. 10 of 14 Spec Summary of the specification Learning Suggested timing (hours) Opportunities Opportunities to ref. content outcomes to develop develop and apply Scientific practical and enquiry What most Communication skills candidates skills should be able to do is not substance substance by throwing possible to change with six dice and getting a predict which time? prediction of the individual number of dice that will Can you nucleus will land on a six. predict, with decay next. Alternatively, drop 20 accuracy, But with a coins and get students which atoms in large enough to predict the number a radioactive number of that will land on a substance will nuclei it is head. decay first? possible to predict how Describe the many will process of decay in a radioactive certain decay as being amount of a random event time. analogous to flipping lots of coins – not knowing which coins will fall on heads but knowing about half of them will on any given throw. 6.4.2.3 Determination of half-life using The half-life 0.6 Define the term Investigate half-life by calculations and graphical of a half-life. throwing a large methods. radioactive number of Tillich Calculate the isotope is the bricks. Any that land half-life of a time it takes on the side with the radioactive for the odd colour get source from a number of removed and the decay curve of nuclei of the number remaining is the radioactive isotope in a recorded. Plot a graph element. sample to of the number of halve, or the Calculate the throws against number time it takes mass of a of cubes remaining. for the count radioactive Determine the half-life rate from a substance of the cubes (the sample remaining after number of throws containing a given time needed to get the the isotope to when given the number of cubes to fall to half of half-life of the reduce by half). its initial substance and This experiment can level. the initial mass also be carried out of the Students using coins. Is it radioactive should be possible to predict source. able to which cubes or coins calculate the will land on a certain net decline, side? expressed as AQA Education (AQA) is a registered charity (number 1073334) and a company limited by guarantee registered in England and Wales (number 3644723). Our registered address is AQA, Devas Street, Manchester M15 6EX. 11 of 14 Spec Summary of the specification Learning Suggested timing (hours) Opportunities Opportunities to ref. content outcomes to develop develop and apply Scientific practical and enquiry What most Communication skills candidates skills should be able to do a ratio, in a radioactive emission after a given number of half-lives. HT only. 6.4.2.4 How to handle radioactive Radioactive 0.7 Describe how Compare precautions sources safely to avoid contaminatio radioactive taken by a teacher contamination. n is the contamination handling radioactive unwanted can occur. sources with those presence of used by, say, in a If radiation is materials nuclear power station. dangerous, containing why is it used radioactive in schools? atoms on other How would a materials. person become The hazard contaminated from by radiation? contaminatio n is due to Explain how the decay of the procedure the followed by contaminatin people dealing g atoms. The with radioactive type of sources radiation reduces the emitted risk of affects the contamination. level of If a person gets hazard. contaminated by radiation how are they decontaminate d? Research decontaminatio n techniques for workers exposed to radioactive sources. Describe how decontaminatio n would take place if a person’s clothes or skin have been contaminated

AQA Education (AQA) is a registered charity (number 1073334) and a company limited by guarantee registered in England and Wales (number 3644723). Our registered address is AQA, Devas Street, Manchester M15 6EX. 12 of 14 Spec Summary of the specification Learning Suggested timing (hours) Opportunities Opportunities to ref. content outcomes to develop develop and apply Scientific practical and enquiry What most Communication skills candidates skills should be able to do by a radioactive source. Explain why contamination by a highly active alpha source may be a lot more damaging than a low activity gamma source. 6.4.2.4 The process and uses of Irradiation is 0.5 Explain how Evaluate the use of irradiation. the process fruit is irradiating fruit in terms of exposing irradiated of cost of goods and an object to before sending potential risk due to ionising on a long trip. the exposure of radiation. workers and If radiation is The consumers of the harmful, why is irradiated irradiation process. food irradiated object does using not become radiation? radioactive. When irradiating food, does it become radioactive? Find out the advantages and disadvantages of irradiating food. 6.4.2.4 Safety precautions taken when Suitable 0.5 Describe and Justify the use of dealing with radioactive sources. precautions explain how radioactive sources in must be radioactive school in terms of risk- taken to sources are benefit analysis to the protect used safely students in the class. against any within a hazard the science lab, radioactive looking in terms source used of reducing the in the risk of process of contamination irradiation and reducing may present. the exposure to the radiation itself. Explain the safety requirements

AQA Education (AQA) is a registered charity (number 1073334) and a company limited by guarantee registered in England and Wales (number 3644723). Our registered address is AQA, Devas Street, Manchester M15 6EX. 13 of 14 Spec Summary of the specification Learning Suggested timing (hours) Opportunities Opportunities to ref. content outcomes to develop develop and apply Scientific practical and enquiry What most Communication skills candidates skills should be able to do needed in a work place that deals with radioactive sources. Research the types of food irradiated at the sources of radiation used in this process. Find out the safety precautions taken in the food industry when dealing with radioactive sources and how this differs from the use of radioactive sources in schools.

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