CHEMISTRY A301 UNIT Three CHAPTER Four Section ONE NAME ...

CHEMISTRY A301UNIT ThreeCHAPTER Four Section ONENAMEDATEPERIOD1. List five things that distinguish elements from each other.2. What is an octave according to John Newlands?3. Why were there gaps in Dmitri Mendelleev’s periodic table?4. What were the main features of organization used to organize his table?5. What elements are out of order on Dmitri Mendelleev’s periodic table compared to today’s periodic able?6. What is the periodic law?7. List the chemical families we identify today on the periodic table.8. What is the common feature of all the elements in chemical families?9. Which elements are the most stable?10. What does stable mean?11. Explain why Dmitri Mendelleev’s periodic table was useful to him and chemists of his time.12. What is electronegativity? List two elements having the highest electronegativity. Two with lowest.

CHEMISTRY A302UNIT ThreeCHAPTER Four Sections TWO & THREE1. What are the main characteristics of the elements classified as metals?NAMEDATEPERIOD2. What is a conduction band?3. Why will crystalline copper conduct electricity easily while crystalline carbon will not?4. Why will metals conduct electricity more easily at lower temperatures?5. Define what is meant by Malleable and ductile.6. Why does conductivity for nonmetals increase with temperature?7. Which components in an atom form the bonds to other elements?8. What are the names of the typical crystal structures metals form?9. What is electron affinity? Given an example.10. How does electron affinity change as we view elements from the left to the right on the periodic table?

CHEMISTRY A303CHAPTER FOURSECTIONS THREE AND FOUR1. What is the difference between bond radius and a van der Waals radius?NAMEDATEPERIOD2. What is the periodic trend demonstrated when lithium, sodium and potassium are added to water?3. How does the radius of elements change as they are viewed across the periodic table? Down the periodic table?4. What is electron shielding?5. How does it influence element size?6. How does increasing atomic number influence element size?7. What is ionization energy?8. Which chemical families have (a) the lowest electron affinity and (b)the highest electron affinity?9. Do metals or nonmetals have higher boiling points? Give examples including what the boiling point value.10. What is meant by Naturally Occurring Elements?11. Complete the following nuclear reactions.a. 4 2He + 14 7N ----> 17 8O +____ b. 8 4Be + 4 2He--->____ c. 240 96Cm----> ____ + 4 2He12. E=MC 2 is an equation used to help describe the results of nuclear reaction. What does it tell us about a nuclearreaction?

CHEMISTRY L301BLACK BOX LABCHAPTER FOURNAME_______________DATE________________PERIOD______________Select one of the boxes supplied. Try and determine what is in the box without crushing, opening or anything else thatdisturbs the integrity of the box. When you are done with this lab you should have two items: 1) a list of ten characteristicsfor the item in the box and 2) a thirty-word paragraph describing what is in the box.

CHEMISTRY L302Periodic Trends of the Alkaline Earth MetalsUNIT FOURNAMEDATEPERIOD_____________Overview: In today's experiments, you will be working with two alkaline earth metals, magnesium and calcium. You findthese two elements in the same column on the Periodic Table. That means they are in the same chemical family. To saythese two elements are in the same chemical family is to make an analogy to a human family in which some of thecharacteristics between the members are the same and some are different. By the end of today's lab, you should learnabout some characteristic reactions of the alkaline earth metals, see in what ways these two metals are the same, andobserve some of the differences.MATERIALSpH paperCalcium metalMagnesium metal2M Hydrochloric acidCalcium hydroxide,Calcium chlorideCalcium oxideMagnesium chlorideProcedure A: Alkaline Earth metals and water1. Obtain a 2-3 cm piece of magnesium and a piece of calcium metal using tweezers. Examine their appearances. Holdeach metal with the tweezers and scrape off the surface until you see a shiny surface. Record your observations:a. What clues does the surface appearance of these metals give you about the reactivity ofthese two metals with air?2. Fill two test tubes half-full with tap water. Tap water is not pure H 2 O, but is not going to alter these pH tests. Put thetubes in your test-tube rack. Test the pH (acidic or basic property of the solution) ⇒by dipping a stirring rod into the waterand touching it to a piece of Universal Indicator paper. Record observations.3. Drop a small piece of calcium metal into one of the test tubes and a small piece of magnesium into the other. Observeand record. (Caution the reaction can be very hot.)b. From what you observe in the test tubes, what can you state about the reactivity of thesetwo metals with water?c. You have seen a demonstration of the reactivity of the alkali(Li vs Na) metals with water. What do you predictabout the reactivity of strontium metal with water and air as compared tomagnesium and calcium?4. Test the pH of the solutions in the test tubes again. Record your observations.5. The white substance formed in the reaction is an ionic compound. Make a hypothesis about what this product is. Thendo a pH experiment with the available salt(s) of your choice and see whether the pH result is consistent with the pHmeasured in Step #4. (Four salt samples of Ca(OH) 2 , CaCl 2 , MgCl 2 and CaO. Are available at the end of the lab bench foryou to use. Take very small amounts of these and add a small amount of water to each.)Hypothesis:d. In one of the reactions you should have seen bubbles of gas being formed. Of what doyou suppose these bubbles of gas are made?Procedure B: Alkaline Earth metals and HCl1. Obtain another very small piece of calcium and another small piece of magnesium. Measure 5 mL of 2M hydrochloricacid (HCl) into each of two beakers. Drop a piece of metal into each of the beakers and observe the results. Recordyour observations:

e. What differences do you notice between the reaction of calcium with HCl and the reaction of calcium andwater, which you ran before?f. What differences do you notice between the reaction of magnesium with HCl and thereaction of magnesium and water, which you ran before?2. Test the pH of the solutions in these two reactions after the reactions are completed, and compare them with the pH ofthe solutions after the reactions with water. Record your observations:g. What evidence do you now have that one product of the reaction of calcium with HCl isdifferent that a product of the reaction with water?h. What explanation can you give for why the product of calcium with HCl ends up looking different than thereaction of calcium with H 2 O? Use the salts provided to test your hypothesis. (Hint: The 2 M HCl you are using ismostly water.Hint 2: Think solubility here.)i. What substance(s) do you think have been formed in the reaction of calcium with HCl?j. Based on the fact that calcium and magnesium are in the same family, what substance doyou think has been formed in the reaction of magnesium with HCl?k. Predict the strontium-containing product of a reaction between strontium metal andHCl.

Summary Questions:l. What general properties can you state regarding alkaline earth metals (both chemical and physical) after thisexploration?m. Your mother has probably told you that calcium is an important part of your diet. Do you think it would bereasonable for you to eat calcium metal atoms as a dietary calcium supplement? Explain.n. Do you think your bones and teeth contain calcium metal atoms or calcium ions?o. Strontium-90 is a radioactive isotope of strontium that is a dangerous product of nuclear fallout whether fromnuclear weapons’ blasts or from nuclear reactor accidents. Based upon your understanding of similarities ofproperties of elements in a chemical family, explain why this isotope of strontium ions is so dangerous to humansif it is spread around in the environment. (Hint: where do you think the Sr would go in your body?)

CHEMISTRY L303Periodic Trends of the HalogensUNIT FOURNAMEDATEPERIODIntroductionAs alchemists discovered more and more elements and compounds they needed a way to organize their information. Theperiodic chart is an outgrowth of that need. The elements in each column on the periodic chart have similar properties. Forinstance the halogens all form ions having a 1 - charge (fluoride, chloride, bromide, and iodide ions). The 1 - charge resultsfrom a neutral halogen atom attracting an electron from another atom, molecule, or ion. You might expect that there wouldbe some variation in the individual members of the halogen family to hold onto the acquired electron. In this laboratoryexperiment you will explore the ability for the members of the halogen family to attract electrons. Variations in a propertysuch as the ability to attract electrons are called trends. Knowing trends in properties will enable you to fine-tune yourchemical knowledge.In this experiment you will synthesize chlorine, bromine and iodine to study their ability to serve as oxidizing agents. Anoxidizing agent is a substance that acquires one or more electrons from another substance. We also say that theoxidizing agent itself gets reduced, that is, gains electrons. There is a trend (periodic behavior) of relative oxidizingstrength among the halogens. You will discover this trend by performing experiments using the halogens and theircorresponding halide ions.MaterialsLiquid Bleach(NaClO(aq))Masking Tape3M Nitric acidPetri Dish Rector1 M Sodium Bromide1 M Sodium IodideMeet the halogensThe name "Halogen" refers to the Group VIIA elements; fluorine, chlorine, bromine, iodine and astatine. The name itself isderived from the Greek words for "salt makers." This accurately describes the tendency of these elements to form saltswith a variety of metals. Fluorine and astatine will not be studied in this laboratory. Fluorine is an extremely toxicsubstance. Many well-known scientists of the 19th century lost their lives while in search of this element. We do not intendto expose you to this danger! Astatine, a radioactive element does not exist in large quantities, is not suited for study,either. You will learn how to prepare the halogens and study their oxidation powers. Before starting into the experiment,let's introduce the players.Chlorine. Chlorine is used in the production of insecticides, dry cleaning agents, disinfectants, and bleach. It was firstprepared in 1774 by the action of hydrochloric acid (HCl) on manganese (IV) oxide (MnO 2 ). Although its properties werestudied in the years that followed, it was not until 1810 that it was shown to be an element. The name chlorine is takenfrom the Greek for greenish-yellow, which aptly describes the color of this gas. One of the most important applications ofchlorine is its use as a bleaching agent. A bleaching agent is a chemical that acts as an oxidizing agent (oxidizes anothersubstance). It removes color from materials by oxidizing the color-causing chemical to a colorless one. Initially, chlorinegas was dissolved in water to form a crude bleach called chlorine water. The irritating odor made it difficult to work with.To improve working conditions, workers wore handkerchief masks soaked in a basic solution. This removed the irritatingchlorine vapors. When chlorine is dissolved in a basic solution, chloride (Cl 1- ) and hypochlorite ions (ClO 1- ) are formed.The hypochlorite served as a strong bleaching agent. Even today, solutions of hypochlorite are used as household bleach.Bromine. Bromine is a red liquid at room temperature. The name is derived from the Greek word "bromos" meaning"stench." It was first prepared in 1826 when chlorine gas was passed through concentrated solutions of sea water. Fromthis, the red liquid was tap. Sea water contains small amounts of bromine as bromide (Br 1- ) ion. This method is still usedtoday to prepare bromine commercially and is essentially the way you will make bromine for this experiment.Iodine. Iodine is a purple-black solid. Its name is derived from the Greek word for violet. This element was first observedin 1811. The synthesis of iodine probably occurred by accident. A French scientist named Courtois was studying the saltsobtained from ash of algae. Water was added to the ash to dissolve all salts. Since sulfur-salts were present, a commonpractice was to add sulfuric acid to remove them. While performing this procedure, Courtois probably added an excess ofsulfuric acid. He immediately noticed a violet vapor rising from the container. The vapor had an odor similar to chlorine.When the vapor condensed on cold objects, a liquid did not appear, but instead, beautiful dark crystals appeared.Iodine is also found in some sea creatures, such as sponges. Interestingly, burnt sponge was used as a treatment forgoiter, an enlargement of the thyroid gland. Could it be that iodine was the active ingredient in the sponge? In 1820, aFrench doctor made this connection and introduced iodine as a successful treatment. The only problem was iodinecaused stomach cramps in those who used it. It was later found that the sodium and potassium salts of iodine (NaI andKI) could be used to treat goiter without this ill effect. Iodide (I 1- ) ion is necessary in the production of thyroxine in the

thyroid gland to prevent goiters. To ensure people receive enough iodide in their diet, "iodized" table salt contains a smallamount of KI.NOTE: the word halogen is used to refer to the neutral, diatomic species. The word halide ion is used to refer to themonatomic ion that forms when a halogen gains an electron (is reduced).In this experiment you will synthesize chlorine, bromine, and iodine to study their ability to serve as oxidizing agents.Oxidation is defined as the loss of electrons from a substance. Reduction is defined as the gain of electrons from asubstance. An oxidizing agent is a reagent that acquires electrons from another substance. We will also say that theoxidizing agent itself gets reduced, that is, it gains electrons. A reducing agent is a reagent which loses electrons toanother substance. We also say that the reducing agent itself is oxidized. There is a trend (periodic behavior) of relativeoxidizing strength among the halogens. You will discover this trend by performing experiments using the halogens andtheir corresponding halide ions. Once you have established this trend, you must explain it using your knowledge ofperiodicity of one periodic property (ionization energy, electronegativitiy, etc.)One type of reaction involving chlorine is an oxidation-reduction reaction, chlorine grabs electrons from anothersubstance. A general example is given below:Cl 2 + 2X 1- →X 2 + 2Cl 1-where X 1- is a negative ions of a halogen called a halide ion (X = Cl, Br, or I). Notice that the chlorine goes from a neutralmolecule to a negative ion. The formation of chloride ion requires chlorine to grab an electron from the halide ion. In thisreaction, chlorine is acting as an oxidizing agent. The halide ion goes from a negative ion to a neutral molecule. Thehalide ion is acting as the reducing agent.LABORATORY PROCEDURE.A. Chlorine gas production.You will produce chlorine gas in a closed petri dish, using a simple chemical reaction. Your laboratory instructor will showyou how to use the petri dish reactor. Place the dish on a plain white paper. Using the entry port(small hole), place one drop of bleach inside the petri dish. Add one drop of 3 M HNO 3 onto thedrop of bleach. Seal the entry port with a piece of tape. Rinse the droppers in a beaker of cleanwater after each use. Record your observation of chlorine gas production:B. Neutralizing Chlorine GasRinse the droppers in a beaker of clean water after each use.Add three drops of 3 M NH 3 onto the drop of nitric acid and bleach. Wait 60 seconds for complete neutralization.Remove the lid. Add just enough water to cover the bottom of the dish. Pour the mixture into the waste bucket. Dry thedish with a paper towel. You must perform this procedure after every experiment!C. Oxidizing Power of ChlorineRinse the droppers in a beaker of clean water after each use.Chlorine gas and sodium bromidePlace one drop of 1 M NaBr in the petri dish using the entry port. Carefully rotate the lid so the entry port is no longerabove the drop of NaBr. Using the entry port, add one drop of bleach to one drop of 3 M HNO 3 in the petri dish, beingcareful not to mix the bleach and nitric acid with the NaBr (sodium bromide). Seal the hole with tape to prevent the escapeof chlorine gas. Record all changes you observe over the next several minutes.Remember, color change, formation of a gas, etc, are signs of a reaction. When youare done, take the petri dish to the fume hood and neutralize the chlorine gas.Chlorine gas, sodium iodide and sodium chlorideRepeat the above procedure, placing one drop of 2M sodium iodide (NaI) through the hole in the petri dish lid, rotate thelid two inches and place one drop of 2M sodium chloride (NaCl) through the hole in the lid. Rotate the lid again so the holeis between the two drops, add the bleach and nitric acid, seal with tape and recordall changes for several minutes (keeping track of which drop is which). When youare done, take the petri dish to the fume hood and neutralize the chlorine gas.Record your observations:

D. Oxidizing Power of BromineRinse the droppers in a beaker of clean water after each use.First, place five drops of NaBr (sodium bromide) through the hole in the petri dish, so as to make one large drop. Rotatethe lid no more than one inch, add a drop of bleach and nitric acid to generate chlorine gas. Seal the hole and wait forNaBr drop to turn yellow. After waiting several minutes, rotate the lid of the petri dish so that the hole is above the largedrop of NaBr. Remove the drop by inserting a clean, empty microburet through the entry port and siphoning the drop intoit. The lid of the petri dish must not be lifted during this procedure! The solution in the microburet is a solution of aqueousbromine, Br 2 (aq). Neutralize the excess chlorine gas in the fume hood. Second, in the petri dish, add one drop of theaqueous bromine to one drop each of sodium chloride (NaCl), sodium bromide (NaBr), and sodium iodide (NaI). Recordall change for several minutes:E. Oxidizing Power of IodineRinse the droppers in a beaker of clean water after each use.First, place five drops of NaI (sodium iodide) in the petri dish, so as to make one large drop. Rotate the lid no more thanan inch, add a drop of bleach and nitric acid to generate chlorine gas. Seal the lid and wait for the NaI (sodium iodide)drop to turn orange. After waiting several minutes, rotate the lid of the petri dish, so that the hole in the lid is above thedrop of NaI (sodium iodide)(. Remove the drop by drawing it into a clean (be sure you've rinsed it out with water), emptypipette through the hole in the petri dish and reseal the lid. Do not lift the lid of the petri dish. The content of the microburetis a solution of aqueous iodine, I 2 (aq). You will use this as your source of iodine. Neutralize the excess Cl 2 from the dish inthe fume hood.Second, n the petri dish, add one drop of theaqueous iodine to one drop each of sodiumchloride, sodium bromide and sodium iodide.Record all changes for several minutes:Discussion Questions:1. In the above reactions, identify which halogen was oxidized and which halogen was reduced in each reaction andexplain how you identified each.2. Explain the difference between being oxidized and being an oxidizing agent.3. Predict the oxidizing strengths of fluorine and astatine and explain your reasoning using shielding.

CHEMISTRYPERIODIC TABLE PUZZLE ACHAPTER FOURNAME___________DATE____________PERIOD__________These letters are presented in families, and your task is to arrange these letters in the proper location in the periodic chart.To do this, use the clues given pertaining to certain members of each family. The numbers in each square in the table arethe atomic numbers of the elements.The best way to start is to use the clues to find in which group each family belongs, and then to arrange the elementswithin the family using the other clues. The following elements belong together in families: WXYZ, STUV, ABC, DEF, GHI,JKL, MNO, and PQR.Clues:1. Element M is not the largest in its group and will react with element O to form both MO 3 and MO 2 .2. Elements L & E are from the same period.3. The radius of atoms of element P are smaller than the atoms of element R.4. Element T has the lowest ionization potential in its group.5. Element W is more reactive than element A and element A is more reactive than element D. All three elements are inthe same series.6. The radius of atoms of element H are smaller than atoms of element I.7. Element B is the least reactive alkaline earth element.8. The Lewis dot notation for element K is ·K.9. When elements K and L react L has a positive oxidation state.10. Element Q is the most electronegative element.11. The atomic number of element V is one more than element P.12. Element J is the most non-metallic element in its group.13. Elements C & N are from the same period and react to form CN .14. The oxidation state of element O is 2- in almost all compounds except when bonded to atoms of element Q.15. Element Z is the most active metal in its period.16. The atomic number of Z is 16 more than the atomic number of Y.17. Element E reacts with element P to form EP 3 .18. Element U is the smallest (size of the atoms) element in its period , but not in its group.19. Elment G has the highest ionization potential in its group.The following Periodic Table shows only the Group A elements. Note that the atomic numbers jump from 20 to 31 in thefourth period. This is because elements 21 through 30, the transition elements, belong to the B Groups.IAVIIIA1 IIA IIIA IVA VA VIA VIIA 23 4 5 6 7 8 9 1011 12 13 14 15 16 17 1819 20 31 32 33 34 35 36

CHEMISTRYPERIODIC TABLE PUZZLE BCHAPTER FOURNAME___________DATE____________PERIOD__________The following elements belong together in families as grouped below. The elements listed are not necessarily in order.The letters are not the symbols for the elements.ZRD, SIFP, JXBE, LHT, QKA, WOV, YMC, GUNThe assignment is to arrange these elements in the proper periodic form, according to the information given below. Fill inthe answers in the periodic table provided at the bottom of this page. Use your periodic table for assistance if necessary.1. U has a total of six electrons.(Used as an example below – U is carbon, therefore G and N are either silicon or germanium.)2. A is the second most common element in the atmosphere.3. E is a noble gas.4. S is an alkali metal.5. O is a halogen.6. O has an atomic number larger than V but smaller than W.7. The charge on an L ion is 2+.8. C has five electrons in its outer energy level.9. The atomic mass of T is more than that of H but less than that of L.10. M has an atomic number one less than that of A.11. The electrons of atom N are distributed in three energy levels.12. R has the largest atomic mass of its group.13. F is a gas at room temperature.14. Atom B contains 10 protons.15. Q has an atomic mass less than that of K.16. Y is more metallic than either M or C.17. X has an atomic number one higher than F.18. D has the smallest atomic mass in its group.19. P is the most reactive element in its family.20. J has the greatest density of the elements in its group as listed.21. Atoms of I are larger than those of S.IVIIIII III IV V VI VIIUthe dotted linesprovidea workspace for listingthe familiesGUN

Test and Quiz Review1. How do chemists use the periodic law to classify elements?2. Yttrium, which follows strontium in the periodic table, has an atomic number one greatert han strontium. Barium is18 atomic numbers after strontium, but it falls directly beneath it in the periodic table. Does strontium share moreproperties with yttrium or barium? Explain your answer.3. What determines the vertical arrangement of the periodic table?4. What determines the horizontal arrangement of the periodic table?5. All halogens are highly reactive. What causes this similarity among the halogens?6. What property do the noble gases share? How does this property relate to the electron con figuration of the noblegases?7. Why is beryllium placed in Group 2?8. Use the periodic table to describe the proper ties of the following elements. a. bromine, Br b. rubidium, Rb c.barium, Ba d. neptunium, Np e. xenon, Xe f. promethium, Pm g. tungsten, W9. Argon differs from both chlorine and potasslum by one proton each. Compare the reactivity and electronconfigurations of these three elements.10. How do the electron configurations of thetransition metals differ from the electron configurations of the metals inGroups 1 and 2?11. How do the electron configurations of the atinide and lanthanide series differ from theelectron configurations of theother transitimetals?12. What groups make up the main-blockelements?13. Why is hydrogen in a family by itself?14. Compare the modem periodic table to Mendeleev's periodic table in Figure 4-2. List the differences betweenMendeleev's periodic table and the modern table. 15. Identify the discrepancies in Mendeleev's table that wererectified in Moseley's table.16. While at an amusement park, you inhale helium from a balloon to make your voice higher pitched. A friend saysthis practice is dangerous because the helium will react will your blood and produce toxic compounds. Is your friendcorrect? Explain.17. a. What is happening to the sodium atom shown in the diagram below? b. How will the electron configuration ofthe atom change when the atom becomes an ion' c. Could a potassium atom behave in a similar way? Explain.18. In Mendeleev's periodic table, he placed Be, Mg, Zn, and Cd in one group and Ca, Sr, Ba, and Pb in anothergroup. Use the electron configurations of these elements as evidence to support this order.19. Why would you never expect a Ca +2 or Na +1 ion to exist?20. Calcium ions, Ca +2 , play an important role in muscle relaxation. Potassium ion, K +1 ,is also found in your body.Why is there no danger of K +1 and Ca +2 reacting with each other?21. You read a science fiction story about an alien race of silicon-based life forms. Use information from the periodictable to hypothesize why the author chose silicon over other elements. (Hint: Life on Earth is carbon-based22. Explain why metals are good conductors of electricity.23. Why is a nonmetal, carbon, added to iron to make nails?24. Describe how atoms are arranged in a metal.25. As more shells are added to atoms, the energies of the outer orbitals get closer and closer. Use this to explainwhy C is nonmetal, but Pb is a metal.26. Use Figure 4-27 to explain why the reactivity of alkali metals increases down the group.27. Compare the energy gaps between the conduction band and the outermost electrons in metals and nonmetals.28. Why is metallic nature not considered an innate property of metals?29. What evidence do we have that atoms are spherical in shape?30. Describe the similarities and differences between a face-centered cubic metal crystal and a hexagonal closepackedmetal crystal.31. How will a room-temperature superconductor affect our lives?32. Why don't scientists define atomic radius as the radius of a single electron cloud?33. What periodic trends occur for atomic radius?34. Use an analogy of a football team's offensive line protecting the quarterback to explain the shielding effect ofelectrons.35. How does the periodic trend in atomic radius relate to the addition of electrons?36. Define ionization energy and electron affinity.37. a. What periodic trends exist for ionization energy? b. How does this trend relate to different energy levels?38. What happens to electron affinity values as you move left to right across a period? Explain why these valueschange as they do.39. Identify which trends in the diagrams below describe atomic radius and ionization energy.

40. How do the trends in atomic radius compare with the trends in ionization energy?41. Name three periodic trends you encounter in your life.42. A scientist may measure the radius of an atom five different times and get five different results. His method iscorrect, and his instrumentation is working properly. Explain the results.43. When two elements are involved in a nuclear reaction, a different element is created. How does this happen?44. How does the nuclear fusion process create energy? 45. Cite two reasons why hydrogen is involved in the mostcommon nuclear fusion reaction.46. Compare the two charts below. Why are the most abundant elements in Earth's crust not the most abundant in theuniverse? Explain how the elements in stars formed the elements in Earth's crust. 47. Irene Joliot Curie created thefirst artificial radioactive isotope, phosphorus-30, in 1934 when she bombarded aluminum-27, a shiny metal withconductive properties, with helium nuclei. The resulting product was a nonmetal with completely different properties.What caused the change in properties?48. Years ago, many people dreamed of transforming lead, an abundant metal, into gold, a rare and highly prizedmetal. Could gold be made from lead using the nuclear process described in this chapter?49. Why are technetium, promethium, and neptunium considered naturally occurring elements even though they arenot found on Earth?