Chemistry Properties and Changes PDF

Properties and Changes 5.1 Chemistry is the study of the substances around us: what is in them, what they do, and what they are used for. These substances can be the laboratory chemicals th...

Properties and Changes 5.1 Chemistry is the study of the substances around us: what is in them, what they do, and what they are used for. These substances can be the laboratory chemicals that you will use in this unit. They can also be common things like air, water, the food you eat, and the products you buy. An understanding of chemistry teaches us how to change substances into new and useful products. It also teaches us how to carry out these changes in socially and environmentally responsible ways. Physical and Chemical Properties Does a “whiter than white” Hollywood smile appeal to you (Figure 1)? What are the benefits of a whiter smile? Before you jump on the “whiter smile” bandwagon, check your facts: research the pros and cons using reliable sources. Consider these factors: Teeth are not naturally pure white. They can range in colour from off-white to yellow. Furthermore, teeth naturally darken with age. Whitening your teeth does not make them healthier. Perfectly white teeth are still subject to decay and gingivitis. Whitening procedures are not permanent and must be repeated Figure 1 Should we change the natural periodically to keep the teeth white. colour of our teeth? According to the Canadian Dental Association, the long-term effects of whitening have not been thoroughly researched. There are two common ways of whitening teeth: surface whitening and bleaching. In the case of surface whitening, a hard, abrasive material such as baking soda is used to scrape surface stains off your teeth. Bleaching is a chemical process that uses a reactive substance such as hydrogen peroxide, and sometimes light. We have just described baking soda as being a hard, abrasive material. physical property a description of a Hardness is an example of a physical property of matter. A physical property substance that does not involve forming is a characteristic or description of a substance. Colour, texture, density, smell, a new substance; for example, colour, solubility, taste, melting point, and physical state are other common physical texture, density, smell, solubility, taste, properties. melting point, and physical state Conversely, a chemical property is a characteristic behaviour that occurs chemical property a description of what when the substance changes into something new. A useful chemical property of a substance does as it changes into one or hydrogen peroxide is that it bleaches coloured substances. more new substance(s) Other common examples of chemical properties are listed in Table 1. You will learn more about these properties in this unit. Table 1 Examples of Chemical Properties Chemical property Example reaction of an acid with a base Vinegar reacts with baking soda to produce carbon dioxide gas. flammability Gasoline burns easily if ignited. bleaching ability Hydrogen peroxide breaks down the pigment (colour) in hair. corrosion Discarded batteries in landfill sites break down readily when they come in contact with groundwater. NEL 5.1 Properties and Changes 175  CITIZEN ACTION Cadmium Cleanout Nickel–cadmium or NiCd batteries were the first popular What Can You Do to Help? rechargeable batteries for small appliances (Figure 2). They Search your home for small battery-powered appliances that are no cannot be used indefinitely, though. They lose their ability to longer in use: old cellphones, portable phones, laptop computers, hold their charge after many discharge-recharge cycles. Then cordless power tools, and electric toothbrushes. Check the battery the batteries have to be replaced and disposed of. Some are for the “NiCd” symbol. If it is a NiCd battery, remove it and bring recycled, but many NiCd batteries go to landfill sites. Over time, it to an authorized recycling centre or hazardous waste collection the batteries’ toxic contents leak out. It is estimated that over depot. 50 % of the cadmium leaching from landfills into groundwater comes from NiCd batteries. This is an environmental concern because cadmium is highly toxic. It is a human carcinogen and has been linked to lung, liver, and kidney disorders. Furthermore, cadmium cannot be broken down into a safer substance. The best we can do to reduce the danger is ensure that cadmium does not leak into our air and water. GO TO NELSON SCIENCE Figure 2 NiCd battery WRITING TIP Physical and Chemical Changes Summarizing Text A change that does not produce a new substance is called a physical change. You can condense a text by combining sentences and omitting examples. Changes of state (including melting, evaporation, condensation, sublimation, For example, “A change that does and dissolving) are examples of physical changes. Many physical changes not produce a new substance is can be reversed, while others cannot. Dissolving sugar in water can easily called a physical change. Changes of be reversed by evaporating off the water. The process of cutting logs into state (including melting, evaporation, lumber, however, cannot be reversed. Think of the physical changes that you condensation, sublimation, and dissolving) are examples of physical have encountered today. Are they reversible? changes.” can be shortened to The change that a substance goes through to produce a new substance “Physical changes such as changes of (or more than one new substance) is called a chemical change. Table 2 state do not make new substances.” shows some of the clues indicating that a chemical change may have taken place. Note, however, that these clues are not conclusive evidence that a chemical change took place. For example, boiling water produces a gas; so does mixing baking soda with vinegar. One of these events is a chemical change; the other is not. Which is which? The only way to tell for sure that a chemical change has taken place is to conduct further tests on the products. If the products are different from the starting materials, then a chemical change has taken place. LEARNING TIP Many chemical changes, like a forest fire, cannot be reversed. However, What It’s Like and What It Does some chemical changes can be reversed. For example, the design of A property is like an adjective: it rechargeable batteries is based on a reversible chemical change. As you use describes what the substance is like. the battery, the chemical change that generates electricity produces new A change is like a verb: it describes substances. As the battery is recharged, these substances are changed back what the substance is doing. to the original chemicals. 176 Chapter 5 Chemicals and Their Properties NEL Table 2 Possible Evidence of Chemical Changes Visible change Example Visible change Example A new colour appears. A solid material (a precipitate) forms in a liquid. Heat or light is produced The change is (generally) or absorbed. difficult to reverse. Bubbles of gas are formed. RESEARCH THIS CHEMICALS FOR YOUR HAIR SKILLS HANDBOOK SKILLS: Researching, Analyzing the Issue, Communicating, Evaluating 4.A., 4.B. Hair stylists consider the properties of hair dyes when advising clients on the best product for them (Figure 3). Some hair dyes are temporary, while others are permanent. 1. Research how temporary hair dyes work. 2. Research how permanent hair dyes work. GO TO NELSON SCIENCE A. Using your researched information, classify the action of temporary and permanent hair dyes as either chemical or physical changes. Justify your answer. K/U T/I B. Identify at least one disadvantage of each process. T/I A C. If you were to dye your hair, which process would you use? What concerns would you have about using this process? A Figure 3 This workplace uses chemistry. NEL 5.1 Properties and Changes 177  IN SUMMARY Properties are either chemical properties (which Changes are either chemical changes (in which describe the ability of a substance to form one or a substance changes into one or more different more different substances) or physical properties substances) or physical changes (in which a (which describe a substance when it is not in the substance remains the same substance but process of forming a new substance). changes its physical properties in some way). CHECK YOUR LEARNING 1. (a) Describe an idea in the reading that is new to you. 5. Over time, crusty scales form on the heating coils inside (b) How does this idea add to your understanding? K /U a kettle. These can be removed by covering the coils with vinegar. As the scales disappear, bubbles of gas are observed. 2. Classify each of the following observations as an example of Does this method of cleaning a kettle represent a physical or either a chemical or a physical property. K /U chemical change? Explain. K/U A (a) Liquid nitrogen boils at −196 °C. 6. The solvents in house paint allow the paint to flow smoothly (b) Propane, leaking from a damaged tank, ignites easily. onto a surface. Once paint is exposed to the air, these (c) Silver jewellery tarnishes (darkens) in air. solvents evaporate and the paint dries. It is the job of a paint (d) Spilled oil generally floats on the surface of water. chemist to select the most suitable solvents. A (e) Meat darkens when it is heated on a grill. (a) What chemical and physical properties should these (f ) Sulfur trioxide changes to sulfuric acid in the atmosphere. solvents have? 3. What kind of change is described in each of the following (b) What other characteristics should the ideal solvents have? situations? Justify your answer. K /U 7. Auto mechanics sometimes use cola to remove the crusty solid that forms around battery terminals. When the cola (a) Air is often blended into ice cream to give it a lighter comes in contact with this solid, bubbles of carbon dioxide texture. gas are observed. Is the cleaning of the battery terminal a (b) When popping corn is heated, water inside the kernels physical or chemical change? Explain. K/U A becomes a gas and expands. This creates enough pressure to explode the kernel. 8. Drain cleaners often produce a great deal of heat as they unclog drains. Is the action of drain cleaners a physical or (c) A loud pop is heard when a lit match is placed at the chemical change? Explain. K/U A mouth of a test tube containing hydrogen gas. 9. Adding vinegar to milk causes small lumps called curds (d) Ethanol is used as an alternative source of energy to to form in the milk. Is this a physical or chemical change? power vehicles. Explain. K/U A (e) Geothermal energy from underground hot springs is used to 10. Describe two physical properties and one chemical property heat water to turn turbines and produce electricity. of the materials used for dental braces. K/U (f ) Some silver rings leave a green stain on your finger. 11. After having read this section, has your opinion of teeth 4. Figure 4 shows a warning label commonly found on chlorine whitening procedures changed? Why or why not? What other bleaches. Is this hazard a result of a chemical property information should be considered before having your teeth or a physical property of chlorine bleach? Justify your answer. K/U whitened? T/I Figure 4 Warning label from a bottle of chlorine bleach 178 Chapter 5 Chemicals and Their Properties NEL SCI ENCE OSSLT Processing Hazardous Waste Crusty jars of cleaners, unlabelled bottles of solvents, clogged Even single-use propane canisters can be recycled using spray cans of insecticides, and rusted cans of paint lurk in the a process developed by Hotz Environmental. First, they remove basements and garages of many Canadian homes. It is easy to any remaining propane in the canister using a vacuum system. recycle or neutralize many of these substances at a hazardous Propane recovered from discarded propane canisters can be used waste collection depot. Let’s follow a typical box of household to heat the facility. Then they safely puncture, cut, and recycle the waste as it is processed. empty propane canisters as scrap metal. When hazardous waste arrives at a hazardous waste We obviously need to recycle or neutralize hazardous collection depot, it is first sorted into different classes of materials. waste. The technologies required to perform these tasks are well The workers separate paints, oils, solvents, pesticides, batteries, developed and in place. Table 1 shows the recycling and disposal medicines, and so on (Figure 1). processes for various kinds of hazardous waste. Hazardous household wastes do not have to be an environmental threat. How many Ontario households routinely bring their hazardous waste to waste collection depots for disposal? Unfortunately, only about 10 %. What can you do to make a difference? Table 1 Treatment of Hazardous Waste Products Hazardous waste Process solvents Flammable solvents are burned as (e.g., paint thinner, fuel in high-temperature kilns used adhesives, antifreeze) to produce cement. automobile lead acid Acids are neutralized. batteries Plastic cases are recycled into new Figure 1 About 50 % of the material that comes to a hazardous cases. waste transfer station is paint and motor oil. Lead is refined and used to make The sorted materials are then packaged and shipped to new batteries. a hazardous waste processing company. There, the hazardous propane barbecue Tanks are emptied and refurbished materials are emptied from their original containers into large tanks into new tanks or converted to scrap drums of similar materials. Different types of waste motor oils, for metal and recycled. example, are mixed together into one large container. The oil is pesticides Substances are chemically treated to then shipped elsewhere for treatment and recycling. This process make them harmless. is so effective that almost all the motor oil sold in Ontario is fluorescent lights Toxic mercury in the lights is recycled oil. (Figure 2) collected, purified, and reused. Almost 85 % of the waste paint that you bring to the hazardous waste depot can be recycled. Hotz Environmental Services Inc. receives most of the waste paint in Ontario. At their recycling facility in Hamilton, Hotz sorts waste paint first into oil-based or latex paints. Each type of paint is then further sorted and blended into eight different colour groups. A master technician, affectionately known as the “brewmaster,” controls the colour of each batch. Hotz then sells the paints to large institutional users such as Canadian and foreign governments. Figure 2 Fluorescent light NEL 179 SCI ENCE OSSLT Processing Hazardous Waste Crusty jars of cleaners, unlabelled bottles of solvents, clogged Even single-use propane canisters can be recycled using spray cans of insecticides, and rusted cans of paint lurk in the a process developed by Hotz Environmental. First, they remove basements and garages of many Canadian homes. It is easy to any remaining propane in the canister using a vacuum system. recycle or neutralize many of these substances at a hazardous Propane recovered from discarded propane canisters can be used waste collection depot. Let’s follow a typical box of household to heat the facility. Then they safely puncture, cut, and recycle the waste as it is processed. empty propane canisters as scrap metal. When hazardous waste arrives at a hazardous waste We obviously need to recycle or neutralize hazardous collection depot, it is first sorted into different classes of materials. waste. The technologies required to perform these tasks are well The workers separate paints, oils, solvents, pesticides, batteries, developed and in place. Table 1 shows the recycling and disposal medicines, and so on (Figure 1). processes for various kinds of hazardous waste. Hazardous household wastes do not have to be an environmental threat. How many Ontario households routinely bring their hazardous waste to waste collection depots for disposal? Unfortunately, only about 10 %. What can you do to make a difference? Table 1 Treatment of Hazardous Waste Products Hazardous waste Process solvents Flammable solvents are burned as (e.g., paint thinner, fuel in high-temperature kilns used adhesives, antifreeze) to produce cement. automobile lead acid Acids are neutralized. batteries Plastic cases are recycled into new Figure 1 About 50 % of the material that comes to a hazardous cases. waste transfer station is paint and motor oil. Lead is refined and used to make The sorted materials are then packaged and shipped to new batteries. a hazardous waste processing company. There, the hazardous propane barbecue Tanks are emptied and refurbished materials are emptied from their original containers into large tanks into new tanks or converted to scrap drums of similar materials. Different types of waste motor oils, for metal and recycled. example, are mixed together into one large container. The oil is pesticides Substances are chemically treated to then shipped elsewhere for treatment and recycling. This process make them harmless. is so effective that almost all the motor oil sold in Ontario is fluorescent lights Toxic mercury in the lights is recycled oil. (Figure 2) collected, purified, and reused. Almost 85 % of the waste paint that you bring to the hazardous waste depot can be recycled. Hotz Environmental Services Inc. receives most of the waste paint in Ontario. At their recycling facility in Hamilton, Hotz sorts waste paint first into oil-based or latex paints. Each type of paint is then further sorted and blended into eight different colour groups. A master technician, affectionately known as the “brewmaster,” controls the colour of each batch. Hotz then sells the paints to large institutional users such as Canadian and foreign governments. Figure 2 Fluorescent light NEL 179 5.4 Patterns and the Periodic Table You have already learned that elements are pure substances that cannot be broken down into simpler substances. You probably also know that the element a pure substance that cannot be broken down into simpler substances periodic table is a powerful tool that chemists use to explain and predict the properties of the elements (Figure 1). 1 18 1 H He 2 Period Group 13 14 15 16 17 2 Li Be B C N O F Ne 3 Na Mg Al Si P S Cl Ar 3 4 5 6 7 8 9 10 11 12 4 K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr 5 Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe 6 Cs Ba La Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn 7 Fr Ra Ac Rf Db Sg Bh Hs Mt Ds Rg Uub Uut Uuq Uup Uuh Uus Uuo Figure 1 The elements of the Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu periodic table can be classified as metals (shown in blue), non-metals Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr (pink), and metalloids (green). Table 1 Summary of Properties of Metals and Non-Metals Table 1 provides a summary of the general properties of metals and non- Property Metals Non-metals metals. Note that hydrogen, H, has its example nickel, Ni bromine, Br own unique colour. This is because it state at room temperature solid solid, liquid, or gas has some properties in common with the metals in the first column. However, lustre shiny dull it lacks many of the characteristic malleability generally malleable brittle (if solid) physical properties of metals at room temperature. We cannot really classify electrical conductivity conductors insulators hydrogen as a metal, so we group it on its own. period a row of elements in the periodic table Chemical Periods and Groups The periodic table also categorizes elements into periods and groups. Each group a column of elements in the periodic table with similar properties row of elements on the periodic table is called a period. Each column is a alkali metals the elements (except group of elements with similar properties. Four of the best-known groups of hydrogen) in the first column of the elements are listed below: periodic table (Group 1) The Group 1 elements (with the exception of hydrogen) are the alkali alkaline earth metals the elements in metals. These elements are soft, highly reactive metals (Figure 2). the second column of the periodic table (Group 2) The Group 2 elements are light, reactive alkaline earth metals. halogens the elements in the seventeenth The Group 17 elements are the halogens. They are one of the most column of the periodic table (Group 17) reactive groups on the periodic table. noble gases the elements in the The Group 18 elements are noble gases. Unlike the halogens, the noble eighteenth column of the periodic table gases are so stable that they rarely react with any other chemical. (Group 18) 184 Chapter 5 Chemicals and Their Properties NEL  Figure 2 Lithium, sodium, and potassium react at different rates with water to produce flammable hydrogen gas. The potassium reaction is so vigorous that the hydrogen gas ignites. nucleus Atomic Structure Why do elements behave so differently? The answer to this question lies in p n0 the structure of atoms. Scientists developed a simple model of the atom to n0 p explain the properties of elements. In this model, most of the mass of the atom is concentrated in an extremely small, dense, positively charged core Figure 3 Most of the atom’s volume is called the nucleus (Figure 3). empty space. Most of the atom’s mass is concentrated in the nucleus. The Atoms are made up of three kinds of subatomic particles (Table 2). nucleus takes up only about 1/100 000 Table 2 Subatomic Particles of the volume of an atom. Proton Neutron Electron electrical charge positive neutral negative symbol p+ no e− location nucleus nucleus orbit around the nucleus DID YOU KNOW? Feeling Dense? The number of protons in the nucleus is called the atomic number of the If you could somehow squeeze all element. For example, because carbon contains six protons in its nucleus, the space out of your body’s atoms its atomic number is 6. The elements of the periodic table are arranged in you would be smaller than a penny. order of increasing atomic number. Atoms are electrically neutral, with equal However, that “penny” would be as heavy as you are right now. numbers of protons and electrons. Electron Arrangements and the Bohr−Rutherford Diagram The Bohr−Rutherford diagram of the atom is a useful way of representing the Bohr−Rutherford diagram a model arrangement of electrons around the nucleus for the first 20 elements. In representing the arrangement of electrons Bohr−Rutherford diagrams, each electron orbit is shown as a ring around the in orbits around the nucleus of an atom nucleus. Evidence indicates that only a limited number of electrons can occupy each orbit. The first orbit can hold up to a maximum of two electrons. The second and third orbits can each hold a maximum of 8 electrons. Elements WRITING TIP with atomic numbers above 18 must have some electrons in the fourth orbit. Writing a Summary Because all atoms are electrically neutral, the total number of electrons in these Write one clear sentence for each major orbits must match the number of protons in the nucleus. Recall that this is point. For example, if summarizing the Bohr–Rutherford diagrams, use separate only a model of the atom. The actual behaviour of electrons is much more sentences to explain the orbit of each complicated, but this model meets our needs for now. electron. We can use this model and the periodic table to help us predict the atomic structures and properties of elements. Let’s use Bohr−Rutherford diagrams for hydrogen, helium, lithium, and fluorine to illustrate this idea of electron orbits. NEL 5.4 Patterns and the Periodic Table 185  An atom of lithium is sometimes represented as Li-7. This means that 2p + this particular atom has a mass number of 7. Recall that the mass number is 1p+ the total number of protons and neutrons. Lithium atoms always have three 2n0 protons, so this atom must also have four neutrons in its nucleus. To balance the charge of the three protons, three electrons must be orbiting the nucleus. H He The first orbit can hold up to two electrons. Since the third electron cannot fit in the first orbit, it has to go in a second orbit (Figure 4). Our atomic model suggests that the second orbit can accommodate 3p+ 9p+ up to eight electrons. So, as you proceed from element to element in the 4n0 10n0 second period, the number of electrons in the second orbit increases by one until there are eight: the maximum number. Therefore, fluorine has seven electrons in its second orbit and neon has eight in its second orbit. Li F After neon, another orbit is required to accommodate the next set of eight Figure 4 Bohr−Rutherford diagrams of electrons. The outermost electron of sodium, therefore, is in the third orbit hydrogen (H-1), helium (He-4), lithium (Li-7), and fluorine (F-19) (Figure 5). Notice that the period, or row, number of an element tells you how many electron orbits the atoms have. You can predict that elements 19 and 20, which are in the fourth row, have electrons in a fourth orbit. Beyond this orbit, the model of the atom gets more complicated, but you need not be concerned about these larger atoms for this course. Electron Arrangements and Reactivity The noble gases are known for their stability. They 2p+ 11p+ are so stable that they almost never react with other 2n0 12n0 elements. Why are they so stable? From experimental evidence, chemists infer that the outer electrons of He an element are responsible for the element’s reactivity. Na Since the noble gases all Figure 5 Bohr−Rutherford diagram of 3p+ 10p+ sodium (Na-23). have completely filled outer 10n0 4n0 orbits, we can conclude MATH TIP that there is something Ratio particularly stable about Li Ne A ratio is a comparison of quantities. full outer orbits (Figure 6). The ratio of boys to girls in Ontario is As you will see in the approximately 1:1. The ratio of hydrogen following sections, the atoms to oxygen atoms in a water stability of filled outer 11p+ 18p+ molecule is 2:1. Ratios are usually electron orbits is important 12n0 22n0 expressed using the smallest possible whole numbers. to understanding how elements combine to form compound a pure substance composed compounds. Compounds Na Ar of two or more elements in a fixed ratio are substances made up of two or more elements in a fixed ratio. Figure 6 Lithium (Li-7), 19p+ sodium (Na-23), and potassium 20n0 (K-39) are reactive because of their single outer electron. Helium (He-4), neon (Ne-20), and argon (Ar-40) are stable because they have filled outer K electron orbits. 186 Chapter 5 Chemicals and Their Properties NEL  While the noble gases are very stable, the elements at the other side of the periodic table—the alkali metals—are very reactive. Observations show that every alkali metal reacts with water (Figure 2). Chemists theorize that To see the reactions of some of alkali metals are highly reactive because each of their atoms contains one the alkali metals with water, electron in its outer orbit. GO TO NELSON SCIENCE IN SUMMARY Elements are arranged in the periodic table in The number of electrons in the outer orbit affects order of atomic number (the number of protons the reactivity of an element. in the nucleus). Bohr−Rutherford diagrams illustrate the numbers Electrically neutral elements have the same of protons, neutrons, and electrons in an atom number of electrons as protons in each atom. and the arrangement of the electrons. Elements in vertical columns (groups) in the periodic table all have the same number of electrons in their outer orbits. CHECK YOUR LEARNING 1. What information on the periodic table lets you predict the 6. Look at the physical appearance of the elements in number of electrons in an atom? K/U Figure 7. K/U 2. Compare metals and non-metals in terms of their (a) Classify each element as either a metal or a non-metal. (a) state at room temperature (b) Identify one unusual physical property of element (iv). (b) electrical conductivity (c) Which of the elements are likely to conduct electricity? (c) lustre (d) number of electrons in their outermost orbit K/U 3. Refer to the periodic table to name and write the symbols for the following elements: K/U (i) (iii) (a) the halogen of the second period (b) the alkaline earth metal in the fifth period (c) the noble gas with the smallest atomic number (d) the non-metal in the fifth period with seven outermost electrons (e) the alkali metal of the fourth period (f) the metal of the third period with three outermost electrons (ii) (iv) (g) the unreactive gas of the second period Figure 7 Elements at room temperature 4. Sketch the Bohr−Rutherford diagrams for the following elements: nitrogen (N-14), aluminum (Al-27), chlorine (Cl-35), 7. Compare the number of outermost electrons and magnesium (Mg-24). T/I C (a) within a period 5. Imagine that chemists discovered a new element with atomic (b) within a group K/U number 119. T/I 8. Why are atoms electrically neutral? K/U (a) Use the periodic table to predict what chemical family this element would belong to. 9. Many high schools have banned the use of potassium. What property of potassium may have led to this ban? T/I (b) How many outer electrons would an atom of this element have? (c) Predict one physical property and one chemical property of this element. NEL 5.4 Patterns and the Periodic Table 187 5.5 Atoms and Ions You have surely heard that we are all supposed to drink a lot of water: at least 2 L a day, and more if it is very hot or if we are exercising (Figure 1). While this is generally good advice, too much water can actually be bad for your health. This was the conclusion reached during a scientific study of runners in the 2002 Boston Marathon. During the race, 13 % of the runners sampled in the study developed a condition known as hyponatremia. Symptoms of hyponatremia include disorientation and a loss of balance. The cause? They drank too much water during the race. Excess water can dilute the concentration of sodium in the blood to dangerously low levels—so low that three runners were at risk of dying if left untreated. People have actually died from this condition. When scientists refer to sodium in blood, they are not talking about the shiny metal that reacts vigorously with water that you saw in Figure 2 in Section 5.4. Rather, they are referring to sodium ions. Many ions are necessary for our health. Calcium and phosphorus ions are essential components of bone; iron ions help carry oxygen around the body. Ions get Figure 1 Is water harming this athlete? into our bodies in our food, and our bodies regulate their concentration. How Do Atoms and Ions Differ? As you learned in Section 5.4, an atom is an electrically neutral particle ion a charged particle that results when with an equal number of electrons and protons. An ion is an atom that has an atom gains or loses one or more become charged by gaining or losing electrons. For example, sodium atoms electrons lose one electron when they react with other atoms. Each resulting sodium ion contains 11 positive charges (on protons) and only 10 negative charges (on electrons). Since it has one more positive charge than negative, the sodium ion has an ionic charge of +1. As a result, chemists gave sodium ions the chemical symbol Na1+ or Na+. (Note that the number 1 is usually omitted in chemical symbols.) The other alkali metals also form ions with a single positive charge. Fluorine is one of the most reactive elements. When fluorine reacts, it tends to gain an electron from another atom to form a stable ion called fluoride. Because the fluoride ion has one extra negative charge, it has an ionic charge of −1. The chemical symbol of this ion is therefore F−. In fact, all the halogens form ions with a single negative charge. So, sodium and the other alkali metals (Group 1) lose an electron to form +1 ions, and the halogens (Group 17) gain an electron to form –1 ions. LEARNING TIP sodium, Na+ fluoride, F− How to Represent a Charge on an Ion positive charge (protons) +11 +9 Chemists say that a magnesium ion has negative charge (electrons) −10 −10 a charge of +2, which is read as “plus ionic charge +1 −1 two,” but they write the ion as Mg2+ (with the number first and the plus sign Why do we not find Na2+ or F2−: sodium ions with a +2 charge or fluoride last). You will get used to this convention as you see it used. ions with a −2 charge? To understand why Na+ and F− are the only stable ions that these elements form, we need to consider their Bohr−Rutherford diagrams in relation to those of the noble gases. 188 Chapter 5 Chemicals and Their Properties NEL  The noble gases (Group 18) are stable due to their full outer orbits. Sodium ions and fluoride ions are also stable. Why is this so? To explain the non-reactivity of sodium and fluoride ions, we can compare their Bohr−Rutherford diagrams with that of neon. Neon is the noble gas that is closest to sodium and fluorine on the periodic table. Again, we can use the Bohr−Rutherford model and the periodic table to help us predict the formation of ions. While we are considering the formation of ions from atoms, we do not need to be concerned about the number of neutrons in the nucleus. We can therefore omit them from our Bohr–Rutherford diagrams for now. Sodium In the process of forming a sodium ion (which has a positive charge), a sodium atom must react with another atom and lose one electron. The most likely electron to be lost is the one farthest from the nucleus: the single electron in the third orbit. This farthest electron is the least tightly held to the nucleus. As a result, the sodium ion has the same stable electron arrangement as a neon atom: an outer orbit filled with eight electrons (Figure 2). 11p+ 11p+ 10p+ Na Na+ Ne Figure 2 The sodium atom loses its outermost electron to form an ion. The sodium ion is stable because its outer orbit is full, like that of neon. Fluorine DID YOU KNOW? Fluorine has one less electron than neon. Fluorine tends to react with Fluoride and Dental Cavities other atoms to gain one electron. This reaction gives it the same stable Fluoride ions help make tooth enamel strong. For decades, Canadians have arrangement of electrons as neon. With this extra electron, the fluorine atom been getting fewer dental cavities now has 10 electrons and only 9 protons. It therefore becomes a fluoride ion thanks to fluoride in their drinking with a single negative ionic charge: F– (Figure 3). water. Some dentists have recently noticed an increase in cavities among young children, possibly because these children are drinking bottled water, without fluoride, rather than tap water. 9p+ 9p+ 10p+ GO TO NELSON SCIENCE – F F Ne – Figure 3 The fluorine atom gains one electron to become a fluoride ion, F. Fluoride is stable because its outer orbit is full, like that of neon. NEL 5.5 Atoms and Ions 189  Aluminum The Bohr−Rutherford diagram of aluminum shows that aluminum has three outer electrons (Figure 4(a)). To have a stable outer orbit (like a noble gas) aluminum could—in theory—either gain five electrons or lose three. Experimental evidence shows that metals tend to lose electrons, while non-metals tend to gain them. The result is an aluminum ion with ionic charge +3: Al3+ (Figure 4(b)). 13p+ 13p+ (a) Al (b) Al3+ Figure 4 (a) An aluminum atom has three electrons in its outer orbit. (b) Losing these electrons leaves the aluminum ion positively charged. Sulfur Sulfur has six electrons in its third orbit (Figure 5(a)). To achieve a stable electron arrangement, a sulfur atom reacts with other atoms and gains two electrons. When it does, sulfur forms an ion with the chemical symbol S2− (Figure 5(b)). This is called a sulfide ion. Sulfur can also form compounds without forming ions. You will learn more about these compounds in Section 5.11. DID YOU KNOW? 16p+ 16p+ Hydrogen Hydrogen can form both positive and negative ions. It can gain one electron to fill its only orbit, forming an ion with a charge of −1. More often, though, (a) S (b) S2– hydrogen loses its only electron to form an ion with a charge of +1. Figure 5 (a) A sulfur atom has six electrons in its outer orbit. (b) Filling the outer orbit with electrons makes the sulfide ion negatively charged. Naming Ions cation a positively charged ion We can classify ions as cations—those that have positive charges, and anion a negatively charged ion anions—those that have negative charges. The name of a positive ion is the same as the name of the element: LEARNING TIP sodium forms sodium ions, for example. The name of a negative ion is Cations and Anions determined by adding “ide” to the stem of the name. For example, oxygen Remember “cation” contains the letter forms oxide ions and phosphorus forms phosphide ions. “t,” which looks like a + sign; anions are negatively charged. 190 Chapter 5 Chemicals and Their Properties NEL  T RY THIS IONS AND THE PERIODIC TABLE SKILLS HANDBOOK SKILLS: Analyzing, Communicating 3.B., 10. Some elements gain or lose electrons to form stable ions. Is there 1 18 1 2 a pattern to how elements form ions? In this activity you will 1 H+ explore how some of the first 20 elements in the periodic table 2 13 14 15 16 17 3 4 5 6 7 8 9 10 form ions. In the process, you will learn how to predict the ionic 2 F– charge of elements based on their location on the periodic table. 11 12 13 14 15 16 17 18 1. Figure 6 represents part of the first four rows of the periodic 3 Na+ Al3+ S2– table. The atomic numbers of the first 20 elements are 19 20 indicated. Symbols are also provided for the ions of five 4 elements. Draw a Bohr–Rutherford diagram for the ion formed by each of the remaining elements in Figure 6. Figure 6 (Omit the elements that are greyed out.) K/U C C. How can the ionic charge be predicted from the location of 2. Copy Figure 6 into your notebook. From your Bohr–Rutherford the element on the periodic table? T/I diagrams, determine the chemical symbol of each ion and record in your periodic table. C A D. Use your answer in C to predict the chemical symbol of the ion of each of the following elements: T/I A. Describe the patterns or similarities that exist within a period and within a group for the Bohr–Rutherford diagrams. T/I A (a) barium, Ba (b) iodine, I (c) rubidium, Rb (d) arsenic, As B. Describe the patterns or similarities that exist within a period E. You were not required to determine the ions for the and within a group for the ionic charges. T/I A greyed-out cells in Figure 6. Why? T/I IN SUMMARY Ions are atoms that have gained or lost electrons. Cations have fewer electrons than protons and Many ions have complete outer orbits, so they are therefore have a positive charge. stable. Atoms and ions can be represented by Anions have more electrons than protons and Bohr−Rutherford diagrams. therefore have a negative charge. Anions often Some ions—in the appropriate concentrations— have “ide” at the end of their names. are necessary for good health. CHECK YOUR LEARNING 1. Compare a sodium ion to 5. List three atoms or ions that have the same number of (a) a sodium atom (b) a neon atom K/U electrons as each of the following: 2. (a) Draw the Bohr−Rutherford diagram (without neutrons) (a) S2− (b) Al3+ (c) P3− (d) Kr (e) Cs+ T/I for an atom of each of the following elements: lithium, 6. Suppose that a new element has been made. Chemical tests oxygen, calcium, and phosphorus. show that it is an alkaline earth metal. T/I (b) Draw the Bohr−Rutherford diagram (without neutrons) for (a) Predict how many electrons there will be in the outer orbit. the ion formed by each of the elements in (a). (b) Predict the ionic charge of the ion that this element forms. (c) Write the chemical symbol for each ion. 7. Justify why these ions do not exist under normal conditions. A (d) Name the noble gas with the same electron arrangement (a) K2+ (b) O2− as each ion. T/I C 8. (a) What is the trend in the ionic charges of the elements in 3. Distinguish between a cation and an anion. K/U Groups 1, 2, and 13 of the periodic table? 4. Name these ions. K/U (b) What is the trend in ionic charges of the elements in (a) Mg2+ (b) S2− (c) Fe3+ (d) Br− (e) N3− Groups 15 to 17? K/U 9. What type of drink would you recommend for endurance runners who suffer from hyponatremia? Why? K/U NEL 5.5 Atoms and Ions 191 5.6 Ionic Compounds As you have already learned, sodium is a very reactive metal. Chlorine is a poisonous gas. When these elements mix, a violent reaction occurs. The compound that results, however, is a safe and familiar one: sodium chloride To see a video of this reaction, or table salt (Figure 1). What happens to the sodium and chlorine atoms as GO TO NELSON SCIENCE this reaction takes place? (a) (b) (c) (d) (e) Figure 1 This series of photographs shows what we can actually see during the formation of sodium chloride. (a) Sodium metal (b) Chlorine gas (c) Sodium and chlorine reacting vigorously (d) The product: sodium chloride (e) We recognize sodium chloride, in a more familiar container, as table salt. Making Ionic Compounds from Elements In the previous section, you saw that metals tend to lose electrons to form positive ions called cations. Conversely, non-metals tend to gain electrons to form negatively charged ions called anions. When a metal such as sodium reacts with a non-metal such as chlorine, both processes occur (Figure 2). The non-metal atoms take electrons from the metal atoms. This electron transfer is possible because the metal’s hold of its outermost electrons is weak. At the same time, the non-metal attracts the metal’s electrons strongly. The resulting ions all have the same stable, filled outer electron arrangements as the nearest noble gas. Figure 2 A model of the formation of sodium chloride. (a) A chlorine atom fills its outermost orbit by taking the 11p+ 17p+ 11p+ 17p+ third-orbit electron from a sodium atom. (b) The stable sodium and chloride ions attract each other to form – sodium chloride. (a) Na (b) Na+ Cl Once they form, positive and negative ions from different elements attract ionic compound a compound made up of each other to form compounds. Compounds that are made up of positive one or more positive metal ions (cations) and negative ions are called ionic compounds. For example, sodium chloride and one or more negative non-metal ions (anions) (table salt) is an ionic compound made up of sodium ions, Na+, and chloride ionic bond the simultaneous strong ions, Cl−. For ionic compounds that contain only two elements, one element attraction of positive and negative ions is always a metal and the other is a non-metal. The attraction that holds in an ionic compound oppositely charged ions together in a compound is called an ionic bond. 192 Chapter 5 Chemicals and Their Properties NEL  Large numbers of sodium and chloride ions join together to form an ionic crystal. This crystal consists of alternating sodium and chloride ions, in a ratio of 1:1, extending in three dimensions (Figure 3). This is why the chemical formula for sodium chloride is NaCl. There is no individual “NaCl” particle: the compound always consists of many sodium ions and chloride ions held together in a crystal. – Cl– Na+ Cl– Na+ Cl – Na+ Cl – Na+ Figure 3 (a) Under the microscope, Na+ Cl – sodium chloride appears as cubes. Cl– Na+ Cl– Na+ Cl (b) A crystal of sodium chloride could – – Na+ contain billions of alternating sodium Na+ Cl Na+ Cl and chloride ions. However, the number – Na+ Cl– Na+ Cl of sodium ions is always equal to the Cl– number of chloride ions, so their ratio (a) (b) is 1:1. Some ionic compounds are soluble in water. When they dissolve, they To view an animation of the separate into ions. Water molecules surround each ion as it leaves the crystal dissolving process, GO TO NELSON SCIENCE (Figure 4). This prevents ions from rejoining the crystal. H H O H H O O H H Na+ – Cl– Na+ Cl– Na+ Cl H O O H H – – Na+ O H H Na+ Cl Na+ Cl O H H H Na+ – Na+ Cl– Cl– Cl O Cl– Na+ H H Na + Cl– Na + 17p+ H O H H O – Na+ Cl O H H Cl– Na+ Cl– H Cl– H H O H Cl H O sodium chloride crystal sodium cations H H O + chloride anions 13p+ 17p+ Figure 4 When ionic substances dissolve, their positive and negative ions are pulled away from the crystal by water molecules. The water molecules arrange themselves around ions in particular ways: the oxygen atoms of water molecules are attracted to positive ions and the hydrogen atoms are attracted to negative ions. Al Cl The element aluminum can also react with chlorine gas. Each aluminum 17p+ atom, however, has three electrons to lose, while each chlorine atom can accommodate only one extra electron. How can this be resolved? Each aluminum atom reacts with three chlorine atoms (Figure 5). The result is Cl an ionic compound called aluminum chloride, a common ingredient in Figure 5 Aluminum transfers its three many antiperspirants. When dissolved in water (or sweat), the aluminum outer electrons to chlorine atoms to ions and the chloride ions separate, just like the ions in sodium chloride. form aluminum chloride. NEL 5.6 Ionic Compounds 193  Properties of Ionic Compounds Due to the strength of the ionic bond, ionic compounds are hard, brittle electrolyte a compound that separates solids with high melting points. Most ionic compounds are also electrolytes, into ions when it dissolves in water, which means that they dissolve in water to produce a solution that conducts producing a solution that conducts electricity. As ionic compounds dissolve, their ions are pulled apart by water electricity molecules. The presence of these ions improves the electrical conductivity of water (Figure 6). Pure water is a poor conductor of electricity, but tap water, lake water, and seawater are good conductors because they contain ions from a variety of sources, such as minerals. That is why it is essential to stay out of swimming pools or lakes during a lightning storm. + – Cl– Na+ Cl– Figure 6 Sodium chloride is an electrolyte because it separates into ions when it dissolves. A solution can conduct electricity only if it contains ions that are free to move. T RY THIS TESTING FOR ELECTROLYTES SKILLS HANDBOOK SKILLS: Observing, Analyzing, Communicating 1.B., 2.B. Electrolytes in our water come from a variety of sources. Some 3. Use the dropper to transfer about 2 mL of distilled water are added naturally as water flows over rocks containing minerals. into the palm of your hand. Let the water sit in your hand Others, such as compounds containing fluoride ions, are artificially for about 10 s. added to drinking water to help prevent tooth decay. In this 4. Test the electrical conductivity of the liquid in your hand. activity, you will compare the electrical conductivity of distilled The electrodes of the tester should only lightly touch water before and after it contacts your skin. your skin. Avoid any open sores or cuts. Equipment and Materials: low-voltage conductivity tester; 5. Wash your hands. small beaker; dropper; distilled water A. Why does the conductivity of distilled water change after it Use only low-voltage conductivity testers in this activity. has been in contact with your skin? T/I 1. Add 5 to 10 mL of distilled water to a clean, dry beaker. B. Why is there a risk of electrical shock when handling electrical equipment with wet hands? T/I 2. Test the electrical conductivity of distilled water. 194 Chapter 5 Chemicals and Their Properties NEL  UNIT TASK Bookmark You can apply what you learned in this section about the properties of ionic compounds to the Unit Task described on page 300. IN SUMMARY Elements (a metal and a non-metal) can react to Most ionic compounds have high melting points form an ionic compound. and are hard, brittle electrolytes: they dissolve in During the reaction, the non-metal atoms pull water to form solutions that conduct electricity. electrons away from the metal atoms. Most ionic compounds form three-dimensional The ratio of metal ions to non-metal ions in crystals, with many of each kind of ion in a fixed an ionic compound depends on the number of ratio held together by their opposite charges. electrons each ion gains or loses. CHECK YOUR LEARNING 1. What kinds of elements combine to form ionic 9. Silver reacts with sulfur to form a compound that has two compounds? K/U silver ions for every sulfide ion. Write the chemical formula 2. Look at each of the following pairs of elements. Predict for the compound. K/U whether each pair would form ionic bonds. Explain your 10. Producing sodium chloride (table salt) using the reaction in reasoning. K/U Figure 1 on page 192 is impractical and expensive. Sodium (a) Mg, O (b) Zn, Cl (c) C, F (d) H, F chloride can be extracted from seawater. How could this be 3. Magnesium and chlorine react to form an ionic done using a common renewable energy source? A compound. K/U C 11. (a) Compare the electrical conductivity of pure water, tap (a) Which element is the metal and which is the non-metal? water, and seawater. (b) Draw a Bohr−Rutherford diagram (without neutrons) (b) Why is there a difference? T/I for each element. 12. A penny and a dime inserted into a pickle and connected in (c) How many electrons must the atoms of each element an electric circuit can generate enough electricity to power gain or lose to become a stable ion? a small electric buzzer. Suggest why a pickle is better for (d) Sketch a diagram to show the transfer of electrons this activity than a raw cucumber. A that occurs when these two elements react. Your 13. Table 1 shows the melting points of four Group 1 diagram should be similar to Figure 2 on page 192. chlorides. T/I C 4. Repeat question 3 for lithium and oxygen. K/U C Table 1 Melting Point Data 5. Explain why two non-metallic elements are not likely to Period number form ionic bonds. K/U Compound Melting point (°C) of metal ion 6. When each of these compounds dissolves in water, what NaCI 801 ions are released and in what ratio? T/I (a) NaF (b) Li3N (c) FeCl3 (d) K2O KCI 775 7. Element X has three electrons in its outermost orbit. RbCI 718 Element Y has seven electrons in its outermost orbit. K/U T/I CsCI 645 (a) Classify each of these elements as metal or a non-metal. (a) Copy and complete Table 1 in your notebook. (b) What is the chemical formula of the ionic compound (b) Draw a line graph of the melting point against the formed by these elements when they react together? period number of each metal ion. (Use X and Y as the chemical symbols.) (c) Chemists do not know much about the very rare 8. Dissolved ions are surrounded by water molecules. Group 1 element francium, or its compounds. Extend Explain how the water prevents the ions from forming the line of your graph in (b) to predict the melting point a solid again. K/U of francium chloride. NEL 5.6 Ionic Compounds 195 5.7 Names and Formulas of Ionic Compounds Blue vitriol, cinnabar, Glauber’s salt (Figure 1). These unusual names may sound like the ingredients in a magical potion. However, they are actually the traditional names of three chemicals commonly found in chemistry labs. These names were developed centuries ago, when few chemicals were known. Today, the number of known chemicals has grown to over 10 million! To keep track of them all, chemists have developed a systematic method of naming chemicals. The International Union of Pure and Applied Chemistry (IUPAC) is the organization that decides how chemicals will be (a) named. A common naming system allows scientists around the world to communicate with each other without misunderstandings. Naming Ionic Compounds Many ionic compounds are made up of two elements: a metal and a non-metal. It is therefore logical that the names of ionic compounds have two parts. The first part refers to the metal ion in the compound and the second part to the non-metal ion. Remember that the name of the metal ion remains the same as the name of the neutral metal atom (Table 1) but that the ending of the name of the second ion—the non-metal—changes to “ide.” (b) Table 1 Examples of Naming Ionic Compounds Metal Metal ion Non-metal Non-metal ion Compound magnesium magnesium ion chlorine chloride ion magnesium chloride aluminum aluminum ion oxygen oxide ion aluminum oxide Table 2 gives the ion names of common non-metals found in ionic compounds. Remember, from Section 5.5, that all non-metals form negatively charged ions: anions. Table 2 Names and Charges of Common Anions Name of element Name of ion Ionic charge Ion symbol fluorine fluoride ion −1 F− (c) chlorine chloride ion −1 Cl − bromine bromide ion −1 Br − Figure 1 Some chemicals have been known for centuries, such as (a) blue iodine iodide ion −1 I− vitriol, (b) cinnabar, and (c) Glauber’s salt. At the time of their discovery, there oxygen oxide ion −2 O2 − was no organized way of naming them. sulfur sulfide ion −2 S2 − nitrogen nitride ion −3 N3 − phosphorus phosphide ion −3 P3 − 196 Chapter 5 Chemicals and Their Properties NEL Writing Chemical Formulas of Ionic Compounds When elements form ionic compounds, electrons move from metal atoms to non-metal atoms. The resulting charged ions attract other ions of the opposite charge until the charges balance out. The compound that forms is electrically neutral. In other words, in the compound, the total number of positive charges must equal the total number of negative charges. This basic idea helps us determine the chemical formulas of ionic compounds. LEARNING TIP To determine the chemical formula of an ionic compound, you must first The Zero-Sum Rule figure out the correct number of ions required to produce an electrically The sum of all charges in the chemical formula of the compound must neutral compound. The compound’s total ion charge (the negative and equal zero. This model may help you positive ion charges added together) must equal zero. Here is a strategy understand this idea. It shows that two that will help. chloride ions (triangles) are needed to “complete” the rectangle. The rectangle represents the smallest number of ions SAMPLE PROBLEM 1 Chemical Formula of an Ionic Compound that must combine to give an overall charge of zero. The ratio of ions in this What is the chemical formula of magnesium chloride? rectangle is the same as the ratio of Step 1 Write the symbols of the elements, with the metal on the left-hand side and ions in the chemical formula of the the non-metal on the right-hand side. compound. Mg Cl MgCl2 Step 2 Add the ionic charge of each ion above the symbol. +2 −1 Cl– Cl– Mg Cl + + Mg2 Mg2 Step 3 Determine how many ions of each type are required to bring the total charge to zero. The sum of all charges in the compound must equal zero. Cl– Cl– Total ionic charge: 1(+2) + 2(−1) = 0 Mg Cl Step 4 Write the chemical formula using the (red) coefficients in front of each bracket as subscripts. Mg1Cl2 Step 5 Do not write the subscript “1” in chemical formulas because the symbol itself represents one ion. The chemical formula for magnesium chloride is MgCl2 SAMPLE PROBLEM 2 Chemical Formula of an Ionic Compound What is the chemical formula of aluminum oxide (Figure 2)? Step 1 Write the symbols of the metal and non-metal elements. Al O Step 2 Add the ionic charge of each ion above the symbol. +3 −2 Al O Step 3 Determine the number of ions required to bring the total charge to zero. 2(+3) + 3(−2) = 0 Al O Figure 2 A layer of aluminum oxide forms a The chemical formula of aluminum oxide is Al2O3. protective coating over the metal underneath. NEL 5.7 Names and Formulas of Ionic Compounds 197  The Crisscross Method for Determining Formulas WRITING TIP Now that you understand the meaning of the symbols and numbers in Writing a Summary chemical formulas, try using a shortcut known as the “crisscross” method. Sometimes a text describes a process or procedure, such as the Crisscross SAMPLE PROBLEM 3 Using the Crisscross Method Method. In your summary, organize ideas and information in the same order What is the chemical formula of magnesium chloride? as in the original text. Step 1 Write the symbols of the elements and their ionic charges. Mg2+ Cl− Step 2 Crisscross the numbers of the ionic charges so that they now become subscripts. Mg2+ Cl− MgCl2 The chemical formula of magnesium chloride is MgCl2. Practice What is the chemical formula of aluminum sulfide? Occasionally, this method of finding the chemical formula of a compound gives you an answer with two identical subscripts. For example, the chemical formula of aluminum nitride appears to be Al3N3. You know that the chemical formula of an ionic compound is always the simplest possible ratio of the ions, so Al3N3 must be simplified to AlN. Elements with Multiple Ionic Charges Chemists have discovered, through experiments, that there are two stable cations of iron: Fe2+ and Fe3+. These ions are named like other cations, except that Roman numerals in rounded brackets are used to indicate the ionic charge (not the number of ions) of the metal. The Fe2+ ion is called “iron(II) ion,” and the Fe3+ ion is called “iron(III) ion.” Because of this, iron may form two different compounds with a particular anion. For example, there are two different compounds of iron and chlorine: FeCl2 and FeCl3. Each compound has its own distinct properties: solid FeCl2 is light green, while FeCl3 is yellowish-brown Figure 3 Because iron has two different ionic charges, it makes two (Figure 3). Several other metals, besides iron, form multiple cations. In each different compounds with chlorine: case, two or more compounds can be formed with the same anion (Table 3). iron(II) chloride (left) and iron(III) Table 3 Names and Multiple Ionic Charges for Common Metals chloride (right). Chemical symbol Chemical symbols Metal of element of ions Names of ions Cu+ copper(I) copper Cu Cu2+ copper(II) Fe2+ iron(II) iron Fe Fe3+ iron(III) Pb2+ lead(II) lead Pb Pb4+ lead(IV) Mn2+ manganese(II) manganese Mn Mn4+ manganese(IV) Sn2+ tin(II) tin Sn Sn4+ tin(IV) 198 Chapter 5 Chemicals and Their Properties NEL Naming Compounds Involving Elements with Multiple Ionic Charges Naming compounds containing elements with multiple ionic charges involves LEARNING TIP the same procedure as before. You must also determine the ionic charge of Specifying the Charge the metal so that you can include it in the name. For example, FeCl2 is called The name of CuCl2 is written “copper(II) iron(II) chloride because the ionic charge of iron is +2. Similarly, FeCl3 is