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1. Slide 1: Science Interactive LTD Copyright 2005 Science Interactive LTD Science base multimedia CD-ROM for PC is a collection of 38 units or tools totalling over 1150 PowerPoint slides. Each unit covers a wide range of different delivery and learning styles, offering an exciting way to involve your pupils during lessons or revision sessions. All styles of teaching and learning are supported through use of high quality images, graphics, challenging exercises and questions. Units can be used in the classroom via an interactive whiteboard, data projector or used during individual study via a PC or school network. Science Interactive LTD. PO BOX 50764 LONDON NW6 9AT email: sales@science-interactive.co.uk web: www:science-interactive.co.uk Unit 1: The Digestive System Unit 20: Crude Oil and its Products Unit 2: The Circulatory System Unit 21: Rock Cycle Unit 3: Healthy Body and Immunity Unit 22: Elements, Molecules and Compounds Unit 4: The Respiratory System Unit 23: Ionic and Covalent Compounds Unit 5: Nervous System and the Senses Unit 24: The Halogens, their Uses and Compounds Unit 6: Human Homeostasis Unit 25: The Noble Gases, their Properties and Uses Unit 7: Hormones and the Endocrine System Unit 26: Rates of Reaction Unit 8: Drugs and Bad Body Maintenance Unit 27: Energy Unit 9: Photosynthesis in Green Plants Unit 28: Generating Electricity and its Domestic Use Unit 10: Water Transport in Plants Unit 29: Electricity Unit 11: Flow of Energy and Elements through the Environment Unit 30: Light and the Electromagnetic Spectrum Unit 12: Mitosis and Meiosis Unit 31: Radioactivity Unit 13: Inheritance and Selection Unit 32: Newton's Forces and the Effects of Forces Unit 14: Evolution and Human Impact Unit 33: Earth and Space Unit 15: Genetic Engineering Unit 34: The Earth and Plate Tectonics Unit 16: The Periodic Table and its Elements Unit 35: The Alkaline Earth Metals Unit 17: The Alkali Metals Unit 36: Sound and Hearing Unit 18: Metals and their Properties Unit 37: Natural Forces Unit 19: The Transitional Metals Unit 38: Cells, Tissue, Organs and Organs systems
2. Slide 2: Science Interactive LTD Copyright 2005 19 F 9 9P+ 35P+ 10N 45N 35 Cl 9E- 35E- 17 Fluorine Bromine 80 35 Br 17P+ 53P+ 18N 74N 127 17E- I 53E- 53 Chlorine Iodine  Unit 24  The Halogens, their Uses and Compounds
3. Slide 3: Unit 24: The Halogens, their Uses and Compounds Science Interactive LTD Copyright 2005 Understand: Keywords: 1. That group VII elements are called the halogens. Halogens, Halides, Physical, Chemical, 2. The physical and chemical properties of the Properties, Ionic, Covalent, Compounds, group VII elements, the halogens. Metals, Non metals, Ions, Bonds, Reactions, 3. That they have similar chemical and physical Atoms, Molecules, Reactivity, Monatomic, properties based on their electronic Diatomic & Antiseptic. configuration. 4. That the halogens can be involved in either ionic or covalent compounds. 5. Their reactions and compounds with reactive metals. 6. Their reactions and compounds with non metals. 7. That their reactivity increases as you ascend the group. 8. The uses of the halogens and their compounds. 9. That the halogens and their compounds have antiseptic properties. Click mouse to begin Science Interactive LTD PO BOX 50764 LONDON NW6 9AT web: www.science-interactive.co.uk email: sales@science-interactive.co.uk
4. Slide 4: Science Interactive LTD Copyright 2005 Physical properties of the halogens one Group VII of the periodic table contains a family of very r________ non-metals known as the halogens. This group contains fluorine, a pale yellow gas, chlorine a pale green gas, bromine a dark brown liquid and iodine a dark purple solid. They are not found in their pure state like gold, but are found tied up in c________ or ionic compounds. They have low melting and boiling points and do not conduct electricity at all. Give a use for the chloride and fluoride ion ? The halogens: Word bank: reactive covalent Position of the halogens The halogens Diagram F 9 Cl 17 Br 35 I 53 Fluorine Chlorine Notes Found in group VII of the periodic table, The halogens have similar chemical properties because all the halogens have seven electrons in they all have seven electrons in their outer shell. Their their outermost electron shell. They are colour darkens as you descend the group from fluorine therefore just one short of a full outer a pale yellow gas to iodine a dark purple solid. Their shell. This is what makes them reactive melting and boiling points also rise as you descend the with other elements. group.
5. Slide 5: Science Interactive LTD Copyright 2005 Physical properties of the halogens two The group VII elements, the halogens are all reactive non-metals, able to form both ionic and covalent compounds with other elements. They have similar physical and chemical properties. They are all diatomic m_________. As you descend the group their colour deepens from pale yellow to dark purple. Their melting and b__________ points also increase with fluorine and chlorine being a gas, bromine a liquid and iodine a solid at room temperature. Give a definition of an ionic and covalent compound ? Physical properties of group VII halogens: Word bank: molecules boiling Boiling point State at room temperature Element Symbol Formula Electron configuration F Colour Fluorine F F Gas 9 -188oC F 2,7 w llo Br I 2 Ye Fluorine Chlorine Cl Cl Gas 17 -34oC Cl 2,8,7 n 2 ee Gr F Br I Chlorine Bromine Br Br 2,8,18,7 59oC Liquid 35 Br I n 2 ow F Br Iodine I Cl I Cl 337oC Solid 53 Br I 2,8,18,18, le 2 7 rp Pu
6. Slide 6: Science Interactive LTD Copyright 2005 General antiseptic properties of the halogens The group VII elements, the halogens are well known for their antiseptic properties. Although they are very toxic to humans at high doses, small quantities of the halogens or their ions (F- Cl- Br- & I-) have an antiseptic effect, destroying many m_______. Our drinking water is now F chlorinated, making sure that we have clean w______ to drink. Our toothpaste contains fluoride to help reduce the amount of bacteria in your mouth. Before surgery, iodine water is applied to our skin to make sure that it is free from microbes. How else can we sterilise surfaces ? Antiseptic properties of group VII halogens: Br I F Word bank: microbes water F Fluorine Chlorine Bromine Iodine F 9 Cl 17 Br 35 I 53 F Cl Br I Fluorine Chlorine Br I Br I Cl Cl All the halogens areClpotentially harmful substances. Fluorine and chlorine in particular are highly toxic. It is highly dangerous to ingest or breathe halogen vapour or their solutions. They are used to kill bacteria therefore sterilising water for domestic supply or in swimming pools. Chlorine compounds are used in disinfectants like 'dettol' or 'TCP'. Iodine water is also used as a disinfectant prior to surgery or to sterilise dirty drinking water.
7. Slide 7: Science Interactive LTD Copyright 2005 Properties and uses of fluorine Fluorine is a pale yellow diatomic gas. Two atoms of fluorine form a covalent molecule, where the atoms share a pair of electrons. Fluorine is the most reactive halogen. Fluorine is found in a wide range of chemicals including teflon a non stick inert coating for kitchen equipment like s_________. Small amounts of fluoride is found in toothpaste, to reduce bacteria in our mouths. Fluorine is also used in CFCs, a refrigerant now banned because of its effects on the o_______ layer. Find out about other uses of fluorine and its compounds ? Properties and uses of fluorine: Word bank: saucepans ozone Fluorine Diatomic gas Non-stick Fluoride Refrigerants F 9 F F Fluorine Fluorine is a pale yellow Fluorine is the most reactive and dangerous of the halogens. It diatomic gas. Two atoms of was used during the first world war to make mustard gas which bond, sharingBrwhen inhaled would destroy your lungs within minutes. Fluorine fluorine covalentlyBr I I two electrons. The formula of forms an extremely stable non-stick compound called teflon. Developed by NASA scientists, it now coats millions of frying fluorine is F2. Fluorine is the pans and artificial implants like hip replacement joints. most reactive halogen.
8. Slide 8: Science Interactive LTD Copyright 2005 Properties and uses of chlorine Chlorine is a pale green diatomic gas. Two atoms of chlorine form a covalent molecule, where the atoms share a pair of electrons. Chlorine is the second most reactive halogen. Chlorine is found in a wide range of chemicals including bleach, a disinfectant used to clean surfaces, f______Fand toilets. Small amounts of chloride is added to drinking water F to kill any remaining b_________. Chlorine is also found in sodium chloride or table salt (excessive salt in the diet leads to high blood pressure and cardiovascular problems) Find out about other uses of chlorine and its compounds ? Properties and uses Br chlorine:Br of I I Word bank: floors bacteria Chlorine Diatomic gas Chlorination Bleach Salt Cl 17 Cl Cl Chlorine Chlorine is a pale green diatomic Chlorine gas is very dangerous if inhaled but in small gas. Two atoms of chlorine amounts it is extremely useful. Since we have chlorinated covalently bond sharing two our drinking water, our life expectancy has risen electrons. The formula of dramatically over the decades. It is also added to chlorine is Cl2. Chlorine is the swimming pools in higher concentrations to kill bacteria. second most reactive halogen. Chlorine is also found in salt or sodium chloride (NaCl)
9. Slide 9: Science Interactive LTD Copyright 2005 Properties and uses of bromine Bromine is a dark brown diatomic liquid. Two atoms of bromine form a covalent molecule, where the atoms share a pair of e________. Bromine is the third most reactive halogen. Bromine is found in a wide range of chemicals including pesticides, which when sprayed on crops kills pests like locusts. Halon f______ extinguishers contain bromine which extinguishes small fires that cannot be put out using powder or water. Small amounts of bromine are added to plastics to prevent their decomposition by bacteria. This is useful for plastics that are used over long periods of time. Find out about other uses of bromine and its compounds ? Properties and uses of bromine: Word bank: electrons fire F F Bromine Diatomic liquid Pesticides Fire extinguishes Plastics Br 35 Br Br I I Bromine is a brownish diatomic Bromine is a very toxic brown liquid, but it does have several liquid. Two atoms of bromine Cl Cl uses. Bromine toxicity is used to kill pests that destroy crops. covalently bond, sharing two Bromine is also used in fire extinguishers. It works by electrons. The formula of reacting with the oxygen, therefore preventing further bromine is Br2. Bromine is the combustion. Bromine is also added to plastics so that bacteria third most reactive halogen and moulds do not rot or decompose them.
10. Slide 10: Science Interactive LTD Copyright 2005 Properties and uses of iodine Iodine is a dark purple diatomic solid. Two atoms of iodine covalently bond sharing two electrons. Iodine is the l_______ reactive halogen. Iodine is found in high concentrations in certain seaweeds and in salt water. Iodine is used by the thyroid gland to make the h_________ thyroxin. Humans require small amounts of iodine in their diets. If iodine is lacking in the diet then goitre, a disease of the thyroid gland can develop. Iodine is also used to sterilise skin prior to surgical operations. Why don’t surgeons use bleach to sterilise the skin ? Properties and uses of iodine: Word bank: least hormone F Iodine F Diatomic solid Goitre Thyroid Sterilisation I53 Br Br I I Iodine is a deep purple diatomic Iodine is used by the human thyroid gland in order to produce Cl solid. Two atoms of iodine Cl thyroxine, an essential hormone. If your diet is poor in iodine, you covalently bond sharing two may develop goitre which is a medical condition where your thyroid becomes enlarged. Iodine is also used to sterilise your skin electrons. The formula of iodine prior to major surgery. It kills the bacteria on your skin. Explain is I2. Iodine is the least reactive why halogens, like iodine have an antiseptic effect ? halogen.
11. Slide 11: Science Interactive LTD Copyright 2005 Reactions of the halogens The halogens can either gain electrons to form negative ions during the formation of ionic compounds or they can form a single covalent bond with other non metals during the formation of covalent compounds. They do this to become like n______ gases, having a full outer shell. The halogens can react with many metal and non metal elements forming a number of different ionic and covalent compounds, for example s_________ chloride (NaCl) and carbon tetra F F chlorine (CCl4) Draw the electronic configuration of a single atom of fluorine and iodine ? + - F + - Cl Li Cl Li Cl F Li Cl Li Cl Li Cl Formation of ionic and covalent compounds: Br Br I Word bank: noble sodium Ionic compounds Br I Br Covalent compounds I Diagram - + - + - Cl Na Na Cl Cl Cl Na Na Cl Cl H Cl Na H Cl Cl Cl H Cl H Cl Sodium + Chlorine Sodium chloride Hydrogen + Chlorine Hydrochloric acid + - + Notes During the formation of sodium chloride (NaCl), - During the formation of the covalent aKsingle electron from theK outer shell Cl sodium K Cl of hydrochloric acid, both atoms form a Cl Cl is K transferred to the outerK shell of a single Cl Cl single covalent bond. This sharing of chlorine atom. Both ions (Na+ & Cl-) are now electrons fills the outer shell of both stable having the same electronic configuration hydrogen and chlorine atoms making as a noble gas. them both stable.
12. Slide 12: Science Interactive LTD Copyright 2005 Ionic halide compounds All reactive metals found in groups I, II and III can form metal halide compounds by losing electrons to the halogens. This group of i______ metal halides includes sodium chloride. They are all soluble and mostly white crystalline solids. Draw a dot and cross diagram for NaI, MgBr2 and FeBr3 Ionic halide compounds:F F Word bank: ionic F Group + Br I Br Br I Li Li Lithium + Chlorine Magnesium + Chlorine Aluminium + Chlorine + 3+ 2- 2+ F Atoms F F Li Li Cl Mg Cl Mg Al O Al Cl O + 3+ Li Li Br Lithium Chloride (LiCl) Br Magnesium Chloride (MgCl2) I Br Aluminium Chloride (AlCl3) I Al Al Ne Ions of atoms + - - + 3+ - 2+ 2- - Li Na Cl Cl Mg O Al Cl Al Cl x2 x3 3+ Others: LiF LiBr LiI Others: MgF2 MgBr2 MgI2 Others AlF3 AlBr3 AlI3 Al Ratio Metal:Halogen 1:1 Ratio Metal:Halogen 1:2 Ratio Metal:Halogen 1:3
13. Slide 13: Science Interactive LTD Copyright 2005 Covalent halide compounds Halogens also react with themselves and other non-metals to form covalent compounds by s__________ electrons with the halogens. Carbon tetra chlorine (CCl4) is an important solvent used in dry cleaning. Draw a dot and cross diagram for C2H4Cl2. F Covalent halide compounds: F F Word bank: sharing Group Br I Br Br Chlorine + Chlorine Carbon + Chlorine Atoms C Cl Cl I I Cl Cl I Cl Cl x2 Chlorine molecule (Cl2) Carbon tetra chlorine (CCl4) Ions of atoms Cl Cl Cl Cl Cl Cl Cl Cl C Cl Cl Cl Cl C Cl Cl Cl Cl Cl Cl Others: F2 Br2 I2 Ratio halogen:halogen 1:1 Ratio non metal:halogen 1:4
14. Slide 14: Science Interactive LTD Copyright 2005 Displacement of halogens from their compounds The halogens become less reactive as you descend the group, for example reactions with other elements involving fluorine and chlorine occur without heating. Reactions with bromine only occur if heated and reactions involving iodine proceed slowly with strong heating. The reason why fluorine is the most r_________ halogen is because it’s the smallest atom and it is the best at capturing or gaining an electron from other e_________ during reactions. What's the rule for the group I metals ? Reactivity of the group VII halogens: Word bank: reactive element Reactivity Reactivity of the halogens during reactions _ _ Fluorine _ _ Chlorine Bromine + + + + Iodine Fluorine Chlorine Bromine Iodine Displaces Displaces Displaces Displaces F Cl Br I Displacement of halide ions from their solution 9 Chlorine 17 Bromine 35 Iodine 53 Nothing Bromine Iodine Fluorine Iodine Chlorine Fluorine will displace chlorine, bromine and iodine ions from their solutions like KCl, KBr and KI, because it is the most reactive halogen.
15. Slide 15: Science Interactive LTD Copyright 2005 Electrolysis of brine (sodium chloride) Chlorine and its compounds are used in huge quantities around the World. Chlorine is extracted from sodium chloride using e____________. During electrolysis the sodium ion regains its single electron forming the metal: sodium. Conversely, the chloride ion loses its electron to form molecular chlorine gas which is then captured at the anode. Equation: Cathode: 2Na+ + 2e- 2Na Anode: 2Cl- Cl2 + 2e- Electrolysis of sodium chloride: Word bank: electrolysis Electrolysis of sodium chloride What happens during the electrolysis Chlorine gas NaCl Anode Cl 17 Molten Sodium Molten Chlorine Cathode Sodium Cathode (-ve) Anode (+ve) Sodium (Na+) ions when Chloride (Cl-) ions when molten Concentrated sodium chloride or brine is molten are free to move. The are free to move. The chloride ions added to the electrolysis cell. This is sodium ions being positively being negatively charged travel to heated and allowed to become molten. charged travel to the negative the positive anode. Chloride ions The current is then switched on and cathode and regain the electron (Cl-) lose their electron and form lost. Molten sodium is formed diatomic chlorine (Cl2.) Chlorine is electrolysis starts. at the cathode. then used as a gas.
16. Slide 16: Science Interactive LTD Copyright 2005 Extension questions and homework 1: Define the following terms: Halogens, Elements, Reactivity, Gases, Ionic and Covalent. 2: Look at the three pictures below. Complete the table. Picture Element Properties and uses One Chlorine Two Iodine Three Bromine 3: Answer the following: a) From physical data, chlorine’s melting and boiling point is -101oC and -35oC. Between what temperatures would chlorine be a solid, liquid and gas. b) All the halogens are diatomic molecules. Explain this term. c) Name a compound in which a halogen can share an electron in a covalent bond. Do a dot & Cross diagram. d) Name a compound in which a halogen gain an electron to form an ion. Do a dot & cross diagram. e) State the type of bonding in the following compounds. Hydrogen fluoride, Lithium chloride, Tetra chloro- methane, Potassium bromide and Hydrochloric acid. f) Draw an atom of chlorine from the information given. 35.5 Cl 17
17. Slide 17: Science Interactive LTD Copyright 2005 4: Complete the following table. Halogen Electrons in outer shell State at room temperature Colour Symbol Fluorine 7 Chlorine Gas Bromine Brown Iodine I 5: Answer the following questions: a) The chemical reactivity of the halogens decreases as you go down the group. Explain why. b) The boiling and melting points of the halogens increases as you go down the group. Explain why. 6: Complete the following table: Write down the salts formed during the following reactions. Reactants Salt Formula Iron + Chlorine Iron (III) Chloride Iron + Bromine MgCl2 Magnesium + Chlorine Sodium + Iodine 7: Answer the following questions: a) How could you determine the pH of bromine liquid, chlorine gas and hydrogen chloride gas. b) What are silver halide films used for...clue you might have one if you have a suspected broken bone. c) If you electrolyse sodium chloride solution. (i) What ions would be attracted to the cathode (-ve) (ii) What ions would be attracted to the anode (+ve) (iii) Why is it impossible to form sodium when electrolysing a solution of sodium chloride...Explain your answer. Internet: Go to google.co.uk and find out the use of fluoride and chloride in drinking water. What form are they used and when were they first used and what do they aim to prevent.