Topic: Radioactivity (Isotopes pt 2)

Target group

Elementary school student (grades 7. and 8.)

Core curriculum

Elementary school. Chemistry.

I. Internal structure of matter. Pupil:

4) defines the concept of isotope; describes the differences in the structure of isotope atoms, e.g. hydrogen; searches for information on the uses of different isotopes.

General aim of education

The student explains the concept of the radioactive element, discusses the types of radiation and the use of radioactive isotopes

Key competences

• communication in the mother tongue;

• communication in foreign languages;

• mathematical competence and basic competences in science and technology;

• digital competence;

• learning to learn.

Criteria for success
The student will learn:

• exchange nuclear radiation types and determine their penetration;

• explain the terms: radioactive isotope (element) , radioisotope

• indicate radioactive elements in the periodic table;

• explain the origin of radioisotopes in the environment.

Methods/techniques

• expository

  • talk.

• activating

  • discussion.

• programmed

  • with computer;

  • with e‑textbook.

• practical

  • exercices concerned.

Forms of work

• individual activity;

• activity in pairs;

• activity in groups;

• collective activity.

Teaching aids

• e‑textbook;

• notebook and crayons/felt‑tip pens;

• interactive whiteboard, tablets/computers;

• sheets of gray paper;

• colored markers.

Lesson plan overview

Introduction

1. The teacher hands out Methodology Guide or green, yellow and red sheets of paper to the students to be used during the work based on a traffic light technique. He presents the aims of the lesson in the student's language on a multimedia presentation and discusses the criteria of success (aims of the lesson and success criteria can be send to students via e‑mail or posted on Facebook, so that students will be able to manage their portfolio).

2. The teacher together with the students determines the topic – based on the previously presented lesson aims – and then writes it on the interactive whiteboard/blackboard. Students write the topic in the notebook.

Realization

1. Students read the fragment titled „Radioisotopes” and analyze the diagram describing elements in nature. Then they explain what are the durable elements, radioactive elements and radioactive isotopes.

2. Participants familiarize themselves with the with the information presented in the table „Type of particles that make up nuclear radiation”. The teacher discusses particular types of radiation and asks students to think of charge (negative or positive) that α and β particles have - discussion. Students together with the teacher determine the answer and write down it in the form in the abstract.

3. The teacher divides the class into groups, distributes sheets of gray paper and colored markers. Students, using the Internet, textbook and e‑textbook, create infographics about the most important achievements of Maria Skłodowska‑Curie. After completion of activities, the group leaders present the effects of work.

4. Students get acquainted with the fragments „Radioactive elements in our surroundings” and „Is it possible to measure nuclear radiation?”. Then, working in pairs and using the Internet, a textbook or e‑textbook, they carry out task number 2 and task number 3. The indicated couples discuss their studies on the class forum.

5. Students, working individually or in pairs, carry out interactive exercises to check and consolidate knowledge learned during the lesson. Selected people discuss the correct solutions for interactive exercises. The teacher completes or straightens the statements of the proteges.

Summary

1. The teacher plays the recording of the abstract. Every now and then he stops it, asking the students to tell in their own words what they have just heard. In this way, students consolidate information learned during the lesson and practice listening comprehension.

2. The teacher asks a willing student to summarize the lesson from his point of view. He asks other students if they would like to add anything to their colleague's statements.

Homework

1. Carry out task number nr 4.1.

The following terms and recordings will be used during this lesson

Terms

Texts and recordings

Radioactivity (Isotopes pt 2)

A significant number of elements occur in nature as a mixture of isotopes. Isotopes can be stable and unstable. The ones that are unstable decay spontaneously and transform into isotopes of other elements. They are said to be unstable and are called radioactive isotopes or radioisotopes. Elements can be a mixture of stable or unstable (radioactive) isotopes, or contain both types of isotopes. Elements that are composed of only radioactive isotopes (radioisotopes) are called radioactive elements. There are few radioactive elements in nature. For example: technetium ($Z=61$) and promethium ($Z=61$) and elements with atomic number greater than 82.

Radiation, called nuclear or ionizing radiation, is always present when atomic nuclei are decaying. Some radioactive isotopes emit α (alpha) particles and others emit – β (beta) particles. Often radiation γ is also observed. A large amount of energy is released during decay.

Each type of radiation produced by radioactive substances has a different range and degree of penetration through the materials. α (alpha) radiation has the smallest range and can be stopped by a piece of paper. A somewhat thicker layer of another material is needed to stop β (beta) particles, for example thin lead or aluminium sheet. γ (gamma) radiation is the most penetrating – a few‑centimetre thick lead shield is needed to protect against it.

Most radiation absorbed by the matter, including its effect on living organisms, is described by means of the unit called sievert (Sv). In Poland, radiation dose, both from natural and artificial sources, amounts to approx. 3.3 mSv (millisieverts) during the year.

Radiation originating from natural radioisotopes is often referred to as the radiation background. Natural radiation background usually differs in various places throughout the world. It depends mainly on the local geological structure of the ground and the average concentration of noble gas – radioactive radon ${}^{\text{222}}\text{Rn}$ – in the atmosphere.

• Radioactive isotopes are mixtures of unstable isotopes; these are elements of atomic number greater than 82, technetium ($\text{Z = 43}$) and promethium ($\text{Z = 61}$).

• Unstable (radioactive) isotopes undergo spontaneous decay and transform into isotopes of other elements with different decay rate, typical of given isotope.

• Radioactive isotopes can emit three types of radiation: α (alpha) (${}_{\text{2}}{}^{\text{4}}\text{He}$, nuclei of the helium atom), β (beta) (rapidly moving electrons) and γ (gamma) (electromagnetic radiation).

• In nature there are many radioisotopes that are fixed components of water, air and soil. They are a source of radiation called natural radioactivity.

• Harmfulness of radiation depends on its type, intensity (power) and duration.