Tales from the Periodic Table – developing skills while teaching about the elements The suggestions set out here are intended to be complementary to existing learning activities – not a prescriptive lesson with starting point, development, consolidation and plenary, but more a collection of resources to dip into. They were developed by Ed Walsh, Lead Consultant for Science at Cornwall Learning and Collins Education author. Tell Ed how you got on with these ideas and find more Tales at freedomtoteach.collinseducation.com. All of the suggested activities have objectives in addition to ‘knowing more about chlorine’. It might be sequencing, constructing sentences, interrogating text, etc. – the activities are designed to support you in developing these skills in students, in addition to covering the content. Summary of the activities © HarperCollinsPublishers 2012 1 Tales from the Periodic Table – developing skills while teaching about the elements ‘Properties of chlorine’ dominoes This activity is an engaging way to summarise key properties. Each domino has a ‘head’ and a ‘tail’, but not matching ones. The idea is to set them out in a complete loop so that the sentences are complete and correct. This can also be done orally, with each student having one ‘domino’ card. One student reads a ‘head’ and the student with the correct ‘tail’ reads both that and the ‘head’ attached to it, and so on. The purpose of the activity is to refresh students’ understanding at the end of a topic and also to develop listening skills and sentence construction. At room temperature chlorine is … … the first surgical anaesthetic was chloroform, with the formula CHCl3 Chlorine is a component of various compounds … ... a yellowish‐green gas, with the formula Cl2 The chemical industry uses chlorine to make a ... the most familiar of which is table salt wide range of substances … PVC is used to make many useful domestic products … ... including bleach, pesticides, antifreeze and PVC (polyvinyl chloride) Chlorine concentrations of 1 mg/litre take less … including pipes, floor coverings, bottles and than a minute … waterproof clothing Chlorine is being used less as a disinfectant, in … to kill bacteria, such as E. coli favour of ozone and ultraviolet light … Chlorine has a long history of medical applications ... … due to health considerations Answers: At room temperature chlorine is … ... a yellowish‐green gas, with the formula Cl2 Chlorine is a component of various compounds … ... the most familiar of which is table salt The chemical industry uses chlorine to make a ... including bleach, pesticides, antifreeze and PVC wide range of substances … (polyvinyl chloride) PVC is used to make many useful domestic products … … including pipes, floor coverings, bottles and waterproof clothing Chlorine concentrations of 1 mg/litre take less ….to kill bacteria, such as E. coli than a minute … Chlorine is being used less as a disinfectant, in … due to health considerations favour of ozone and ultraviolet light … Chlorine has a long history of medical applications ... … the first surgical anaesthetic was chloroform, with the formula CHCl3 © HarperCollinsPublishers 2012 2 Tales from the Periodic Table – developing skills while teaching about the elements Poem This includes a variety of references to chlorine and its properties. The idea is for students to look at the text, firstly to identify the element and secondly, more importantly, to work out the properties and uses referred to. The purpose is to put the concepts in a different form so that revisiting ideas becomes more engaging. Chlorine
Some might call me a little obsessive,
the way I like to keep things clean,
I am bacteria’s biggest foe,
I am the king when it comes to hygiene.
Whenever you go camping
and you drink from a natural stream,
just pop me in your water bottle;
one pill of me holds a germ‐killing team!
I’m used in anaesthetics
and I help the pain to ease,
you can spread me round your kitchen
to avoid catching disease.
I’m used to clean your bathroom,
I can make PVC,
face it kids, you’d find it hard
to live your life without me.
If that’s not enough to convince
you that us elements are cool,
remember next time you go swimming
that’s me who smells good in the pool!
© HarperCollinsPublishers 2012 3 Tales from the Periodic Table – developing skills while teaching about the elements Card sort: timeline of chlorine This is a sequencing activity in which students are given a timeline and a set of events on cards to match to it. The purpose is not to suggest that students should know the dates but rather that they should be able to work out a likely sequence by considering the events. Please note that the events are listed below in the correct chronological order. 1774 1785 1810 1826 1847 1850 1912 1915 Cards: Chlorine was studied by Carl Wilhelm Scheele in Sweden; he recorded the yellow–green colour and found out that it would kill insects. Chlorine was used to bleach textiles. Sir Humphry Davy concluded that chlorine was an element and named it, from the Greek chloros, which means green–yellow. Silver chloride was first used to produce photographs. Chlorine was first used as an antiseptic to prevent the spread of fever in a hospital. Chlorine was first used to purify a water supply after an outbreak of cholera in London. Polyvinyl chloride (PVC) was invented; at first no‐one could think of a purpose for it. Chlorine gas was first used as a weapon at Ypres by the German Army. © HarperCollinsPublishers 2012 4 Tales from the Periodic Table – developing skills while teaching about the elements Pictorial prompts – what links these pictures? Photo by www.localfitness.com.au This activity challenges students to identify how the pictures are related and explain how chlorine plays a role in each. The purpose is to encourage students to use evidence and make connections. Patterns in the Periodic Table – relations to neighbours both in period and group In this activity students look at chlorine’s neighbouring elements, both in the same period and in the same group, and work out which of these has a stronger set of common features. The purpose is to identify key characteristics of groups of elements. Ask students to: • find chlorine in the Periodic Table; it is in a group (the column) and a period (the row) • find out about its neighbours in the same period and make brief notes about what they are like • find out about its neighbours in the same group and make brief notes about what they are like • decide: does chlorine seem to have more in common with the other elements in the group or with other elements in the period? • make a list of what chlorine seems to share with other elements in the same ‘family’. © HarperCollinsPublishers 2012 5 Tales from the Periodic Table – developing skills while teaching about the elements Applications and uses Students are presented with a range of pieces of evidence on cards, which they have to manage, to decide which is useful in answering a particular question. The purpose is to encourage students to evaluate evidence and determine its usefulness. Questions might include: • What evidence is there to support the view that chlorine is essential in modern life? • What is the evidence to support and to oppose the view that chlorine is more of a hazard than an asset? • What are the effects of chlorine on the human body? Cards: 1. Chlorine is used to make textiles, plastics, dry cleaning solvents, drugs, insecticides, dyes and cleaning products. 2. Chlorine is used to make PVC. 3. Chlorine is an important chemical for water treatment, disinfectants and in bleach. 4. Chlorine is used to kill bacteria in water supplies and public swimming pools. 5. A problem with using chlorine in swimming pools is that it reacts with hair and skin, because they are made from protein. 6. Chlorine gas is known as bertholite. 7. Chlorine was used as a weapon in World War I by Germany in the Battle of Ypres. 8. Chlorine gas was described by soldiers as having a smell of pepper and pineapple. It tasted metallic and stung the back of the throat and chest. 9. Chlorine reacts with water in the lungs to form hydrochloric acid which can be lethal. The damage done can be prevented by a gas mask. 10. The use of chlorine gas as a weapon was pioneered by German scientist Fritz Haber; it is alleged that his role in this drove his wife to commit suicide. 11. Chlorine was replaced as a weapon by the more deadly phosgene and mustard gas. Chlorine in the news This activity is designed to get students to read and interact with text. Source and print out a news story about the use of chlorine gas in warfare, for example in Iraq in 2007. (Search for ‘chlorine attack iraq’.) Ask students to: •
highlight ten key words in the article •
rewrite it as a tweet (no more than 140 characters) •
describe the effect of the chlorine •
suggest why chlorine was selected as a weapon.
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