What Do You Think? Investigate GOALS. The Elements of Mystery

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1 Activity 1 Clue Me In GOALS In this activity you will: Use deductive reasoning to arrive at a conclusion. Know and apply different ways in which the elements are classified and organized. Use references, including the periodic table, to learn more about individual elements. What Do You Think? Pretend you are a detective in a crime lab. You are given a piece of material and you must figure out which of the 114 elements on the periodic table the material is. What information would you need to identify a material? How would you decide which element the material is? The What Do You Think? questions are provided to get you engaged in the activity. They are meant to grab your attention. They are also used to find out what you already know or think you know. Don t worry about being right or wrong. Discussing what you think you know is an important step in learning. Record your ideas about these questions in your log. Be prepared to discuss your responses with your small group and the class. Investigate The Elements of Mystery 1. Get two mystery element cards and a periodic table from your teacher for each group of students. 2. Read through the properties listed on the card. 593

2 CSI Chemistry 3. You will play a game with other groups in your class. The rules of the game: When it is your group s turn, you will tell the other groups one of the properties of your mystery element. The leader of any group can then raise his or her hand and attempt to guess the element on the basis of the first property. If the group guesses correctly, it scores one point. If it guesses incorrectly, that group is out of this round. Your goal is to give clues in such an order that nobody is able to identify your element until the last clue is given. You receive 1 point for every clue that you recite. If a team identifies your element after the first clue, you only get 1 point. If the first team to correctly identify your element requires 4 clues, then you score 4 points. Each team gets a chance to provide clues to the first mystery element. After one round, each team gets to go again with their second element. a) At the conclusion of the game, describe the properties that helped the teams identify your material. b) Which properties did not help the team identify the element? Why? Chem Words deductive reasoning: organizing, analyzing, and determining the relationships between different pieces of information to construct a solution to the situation being investigated. DEDUCTIVE REASONING Imagine you get up out of your seat to sharpen your pencil. You leave a candy bar on your desk. (Of course, you are not in the lab!) When you return, you notice the candy bar is missing and you wonder, Where did it go? Your partner, who sits next to you in class, has chocolate all over his face and an identical wrapper sticking out of his book bag. What do you conclude? Your partner took the candy bar and ate it! The process you used to assemble and analyze clues that helped you answer the question is called deductive reasoning. So, in this case, you deduced that your partner ate your candy bar. You based this on the evidence at the scene (the chocolate on his face and the wrapper in his bag). In this activity, you used deductive reasoning skills and a variety of reference materials to identify the mystery element s identity. Often, investigators and forensic chemists are faced with a jumble of facts and evidence that seem to be unconnected. It is the job of the investigator or forensic chemist to organize, analyze, and determine the relationships between different pieces of evidence to reconstruct 594

3 Activity 1 Clue Me In and solve the crime. They are also using deductive reasoning. Some techniques used to analyze information include making lists, making charts, and using the process of elimination. The Elements and the Periodic Table The chair you are sitting on, the clothes you are wearing, the air you are breathing, and you, yourself everything around you is made of matter. All matter is made of elements or combinations of different elements. Elements are the basic building blocks of matter. They cannot be broken down into simpler substances by physical or chemical means. Currently, there are 114 known elements, each represented by a symbol. These symbols, or more specifically atomic symbols, are either one or more letters. The first letter is always capitalized, and the second or third letter, if there is one, is always lowercase. For example, the first element on the table, hydrogen, is represented by the atomic symbol H, and the second element on the table, helium, has the symbol He. Long ago, data on the individual elements was presented to scientists in a jumble. Chemists sought out a way to organize this information. The result is one of the most marvelous references in science, the periodic table. Using the atomic number of each of the elements, scientists have organized the elements on the Periodic Table of the Elements into 18 groups (up-down columns) and seven periods (across rows). Chem Words matter: anything that has mass. element: any material that cannot be broken down into simpler materials. atomic symbols: one or more letters that represent an element in the periodic table. group: a column of elements or family of elements in the periodic table. Example: alkali metals are Group 1A. period: a row of the periodic table. Example: the second period starts with the element lithium and ends with neon. representative or main-group elements: the elements of the periodic table in which the final electron is placed in either an s or p orbital. Example: all of the elements of the second period are representative elements. Elements in the same group have similar chemical and physical properties. Because of this, they are often referred to as families. Some of the families have names. The two groups on the far left and the six groups on the far right are known as the representative or maingroup elements ( )

4 CSI Chemistry Chem Words transition metals: the elements between the representative elements in which the final electrons are contained in the d orbital. inner transition metals: elements that contain f orbital electrons and are called the lanthanides and actinides series. metalloid: an element that possesses both metal and nonmetal characteristics. Silicon, arsenic, and germanium are examples of metalloids. Checking Up 1. Give an example of deductive reasoning. 2. What is the difference between a group and a period on the periodic table? 3. Describe three physical properties of: a) metals b) nonmetals 4. Where on the periodic table are the metalloids located? The groups are: Group 1: alkali metals, which include lithium Group 2: alkaline earth metals, which include beryllium Group 13: no common name, which include boron Group 14: no common name, which include carbon Group 15: pnictogens, which include nitrogen Group 16: chalcogens, which include oxygen Group 17: halogens, which include fluorine Group 18: noble gases, which include helium Groups 3-12 are located in between the representative elements and are called the transition metals. The groups that lie below the others on the periodic table are called the inner transition metals. Elements can also be classified as metals, nonmetals, and metalloids. The metallic elements are located to the left of the stair-step line that starts between aluminum (Al) and silicon (Si) and ends between tin (Sn) and tellurium (Te). Metals are shiny, can be pounded into sheets (malleable), drawn into wires (ductile), and are good conductors of heat and electricity. Nonmetals are located to the right of the stair-step line. Nonmetals tend to be gases or brittle solids at room temperature. They are also poor conductors of heat and electricity. The elements located around the stair-step line on the periodic table are called metalloids. Metalloid elements have both metallic and nonmetallic properties. For example, the metalloid element silicon is shiny like a metal but brittle like a nonmetal. What Do You Think Now? At the beginning of this activity, you were asked: What information would you need to identify a material? How would you decide which element the material is? Review your thoughts in the What Do You Think? section of your log. Now that you have worked specifically with deductive reasoning and have learned more about the properties of elements, create a simple flowchart or concept map of specific questions. Come up with questions about the material that will help you deduce the identity of an unknown element. Be sure your questions have a logical sequence to them that would lead you to the identity of an element. 596

5 Activity 1 Clue Me In What does it mean? Chemistry explains a macroscopic phenomenon (what you observe) with a description of what happens at the nanoscopic level (atoms and molecules) using symbolic structures as a way to communicate. Complete the chart below in your log. MACRO NANO SYMBOLIC Which properties of the element cards referred to observable properties that you could identify with your senses? The elements in the periodic table are organized in families which exhibit similar chemical properties. At the Nano level, fluorine, bromine, and iodine are described as diatomic, meaning that these elements have two bonded atoms as elements. Do you think another member of the same family, chlorine, is also diatomic? Explain your reasoning. Rather than write out the names of elements, chemists use symbols. Write down both the names and the symbols for at least three elements. How do you know? What did you do in this activity that led you to a better understanding of deductive reasoning and matter? Why do you believe? Explain a situation where you have used deductive reasoning in your life, outside of the classroom. Write a short paragraph explaining the scenario and the outcome of your reasoning. Why should you care? Give an example of how you could use the properties of the elements in your crime scene for the Chapter Challenge. Be specific, referencing a particular element you could use. Reflecting on the Activity and the Challenge Part of your task for the Chapter Challenge is creating a crime story for the crime scene you will design. Also, you must make sure that all of the evidence leads to the identification of the correct suspect and that the clues are not too easy or too difficult to follow. Think about how you can use your deductive reasoning skills to design a crime scene that meets all of these requirements. 597

6 CSI Chemistry You will need to use the periodic table to help answer many of the questions below. 1. What element is in group 17 and period 3? 2. What is the name of the group that contains potassium? 3. Which of the following sets of elements contains all transition elements? a) vanadium, strontium, aluminum, titanium b) tungsten, gold, chromium, ruthenium c) tellurium, nickel, phosphorus, magnesium d) zinc, scandium, iron, silver 4. Which of the following sets of elements are all members of the same group? a) cobalt, rhodium, iridium, tin b) silicon, germanium, lead c) iodine, xenon, antimony, indium d) barium, calcium, radium, beryllium 5. Identify the metals and the nonmetals in the following list. I, Lu, V, C, Ho, Co, La, Te 6. Select an element from the periodic table that interests you. Create a mystery element card for it. Describe how a fellow student would use the clues you have listed to identify the element. 7. Preparing for the Chapter Challenge Flip through the entire CSI Chemistry chapter of your book. Pay particular attention to the titles and goals of each section. Also, review your log to identify any possible concepts from previous chapters you feel at this point may be useful in creating crime-scene evidence. In your log, prepare a list of possible evidence that you see you ll learn more about in this chapter. If possible, add to that list any topics you have already studied in previous chapters. For topics from other chapters, briefly write down your thoughts on why they may be useful in the crime-scene challenge. Inquiring Further Timeline in the development of the periodic table In developing the Periodic Table of Elements, as more knowledge was acquired about each of the elements, scientists began to ask, Is there a pattern? Between 1829 and 1934, chemists attempted to use deductive reasoning to answer this question. Research this period of time in chemistry and create a timeline explaining the history and evolution of the current model of the periodic table. Be sure to cite specific scientists and how they used reasoning skills to organize the elements into the current pattern. 598