0072_sx09_K_te_Ch03.fm Page 98 Sunday, January 13, 2008 1:38 PM 4 Nonmetals and Nonmetals and Metalloids 4 Metalloids Objectives After this lesson, students will be able to Reading Preview K.3.4.1 Describe the properties of Key Concepts What Are the Properties of Charcoal? nonmetals. • What are the properties of 1. Break off a piece of charcoal and roll it between your fingers. K.3.4.2 Tell how metalloids are useful. nonmetals? Record your observations. • How are the metalloids useful? 2. Rub the charcoal on a piece of paper. Describe what happens. 3. Strike the charcoal sharply with the blunt end of a fork. Target Reading Skill Key Terms Describe what happens. • nonmetal Using Prior Knowledge Explain that using 4. When you are finished with your investigation, return the • diatomic molecule • halogen prior knowledge helps students connect charcoal to your teacher and wash your hands. • noble gas • metalloid what they already know to what they are • semiconductor Think It Over about to read. Classifying Charcoal is a form of the element carbon. Would Target Reading Skill you classify carbon as a metal or a nonmetal? Use your Answers observations from this activity to explain your answer. Sample answers: Using Prior Knowledge Before you read, write what you know What You Know about the properties of nonmetals 1. Nonmetals are not shiny. and metalloids in a graphic Life on Earth depends on nonmetals. All organisms are made 2. organizer like the one below. As from compounds of carbon. The air you and other living things Nonmetals are not magnetic. you read, write what you learn. What You Learned breathe contains mostly nitrogen and oxygen. Water, a key compound in living cells, consists of hydrogen and oxygen. Yet, 1. Nonmetals are dull and brittle. What You Know while many compounds made with nonmetals are essential to 2. Metalloids have characteristics of metals 1. Nonmetals are not shiny. life, some nonmetals themselves are poisonous and highly and nonmetals. 2. reactive. Still others are completely unreactive. Compared to Teaching Resources metals, nonmetals have a much wider variety of properties. However, nonmetals do have several properties in common. • Transparency K28 What You Learned 1. 2. Preteach Build Background Knowledge L2 Experience With Chlorine Ask: What do you know about chlorine? (Sample answer: Chemical used in swimming pools, part of bleach) Encourage students to These bears, the grass build on their experiences with chlorine in behind them, and all life on Earth is based on swimming pools and share their carbon, a nonmetal. observations. Point out the position of chlorine in the periodic table. Invite students to share any knowledge they may have about elements near chlorine. students that the charcoal has been mixed with clay to keep its shape. Skills Focus Classifying L1 Expected Outcome The charcoal breaks Materials activated charcoal, paper, fork easily, rubs off on fingers and paper, and Time 5 minutes shatters when hit with a fork. Tips Activated charcoal is available where Think It Over Sample answer: Carbon aquarium supplies are sold. You may is brittle, dull, not malleable, and not substitute charcoal briquettes, but tell lustrous. Carbon is not a metal. 0072_sx09_K_te_Ch03.fm Page 99 Sunday, January 13, 2008 1:38 PM FIGURE 20 Instruct Physical Properties of Nonmetals Nonmetals have properties Properties of that are the opposite of metals. Comparing and Contrasting Nonmetals Contrast the properties of these nonmetals with those of metals. Teach Key Concepts L2 Contrasting Nonmetals and Metals The helium filling this Focus Tell students that nonmetals are most blimp is a gas at room often described as anything that is not a metal. temperature. Teach List the properties of metals ᭣ Sulfur crumbles discussed in Metals. Then, list properties of into a powder. nonmetals, opposite the corresponding metal property. Ask: Are nonmetals good Nonmetals are good insulators. Carbon conductors of heat and electricity? (No) In compounds are found what state are most nonmetals found at in the plastic insulating room temperature? (Most are gases, some are these copper wires. solids, only one is a liquid.) Explain that most solid nonmetals are brittle. Ask: What properties of metals are the opposite of brittle? (Malleable and ductile) Properties of Nonmetals Apply Ask: What properties of oxygen make it a nonmetal? (Sample answer: It is A nonmetal is an element that lacks most of the properties of a a gas at room temperature and a poor metal. Most nonmetals are poor conductors of electricity and conductor of electricity and heat.) learning heat and are reactive with other elements. Solid nonmetals modality: verbal are dull and brittle. Look at the periodic table in Section 2. All of the elements in green-tinted boxes are nonmetals. Many of Independent Practice L2 the nonmetals are common elements on Earth. Teaching Resources Physical Properties Ten of the 16 nonmetals are gases at • Guided Reading and Study Worksheet: room temperature. The air you breathe is mostly a mixture of Nonmetals and Metalloids two nonmetals, nitrogen (N) and oxygen (O). Other nonmetal elements, such as carbon (C), iodine (I), and sulfur (S), are sol- Student Edition on Audio CD ids at room temperature. Bromine (Br) is the only nonmetal that is liquid at room temperature. Look at examples of nonmetals in Figure 20. In general, the physical properties of nonmetals are the opposite of those of the metals. Solid nonmetals are dull, meaning not shiny, and brit- tle, meaning not malleable or ductile. If you hit most solid non- metals with a hammer, they break or crumble into a powder. Nonmetals usually have lower densities than metals. And non- metals are also poor conductors of heat and electricity. Differentiated Instruction English Language Learners/ English synonyms or native words. L2 Beginning L1 learning modality: visual Monitor Progress Comprehension: Key Concept Rewrite Writing Instruct students to write down one English Language Learners/ the boldfaced sentences on this page as a characteristic that most nonmetals have. Intermediate L2 list of nonmetal properties. Have students Comprehension: Key Concept Have Answer construct a cluster diagram with students complete the activity at left, but Figure 20 Sulfur is brittle, helium is a gas, “Properties of Nonmetals” in the center do not allow them to use native words. and plastics do not conduct electricity. and each property connected to it by a line. learning modality: visual Metals are bendable, good conductors of Allow students to list properties using electricity, and usually solid at room temperature. 0072_sx09_K_te_Ch03.fm Page 100 Sunday, January 13, 2008 1:38 PM Use Visuals: Figure 21 L2 Chemical Properties Most nonmetals are reac- Electrons and Reactivity tive, so they readily form compounds. In fact, fluo- rine (F) is the most reactive element known. Yet, Focus Remind students that metals react Group 18 elements hardly ever form compounds. with other elements by losing electrons and Atoms of nonmetals usually gain or share elec- nonmetals react by gaining or sharing trons when they react with other atoms. When non- electrons. metals and metals react, electrons move from the Teach Direct students to look at Figure 21. metal atoms to the nonmetal atoms, as shown by the Ask: Which element will gain an electron? formation of salt, shown in Figure 21. Another (Chlorine) Which element will lose an example is rust—a compound made of iron and electron? (Sodium) oxygen (Fe2O3). It’s the reddish, flaky coating you Apply Explain that the reactivity of Sodium Chlorine might see on an old piece of steel or an iron nail. Many nonmetals can also form compounds with elements depends on electrons. Ask: Why do – e other nonmetals. The atoms share electrons and the nonmetals in Group 18 rarely react become bonded together into molecules. with other elements to form compounds? (They do not readily lose or share electrons.) In which portion of the periodic table do you find nonmetals? learning modality: visual FIGURE 21 Reactions of Nonmetals The table salt on a pretzel is mined from Families of Nonmetals deposits found on Earth. The same Families of Nonmetals compound can also be formed from a Look again at the periodic table. Notice that only reaction between the metal sodium and Group 18 contains elements that are all nonmetals. Teach Key Concepts L2 the nonmetal chlorine. In Groups 14 through 17, there is a mix of nonmet- Nonmetal Groups als and other kinds of elements. Focus Point out that Group 18 is the one The Carbon Family Each element in the carbon group that consists only of nonmetals. family has atoms that can gain, lose, or share four However, nonmetals in mixed groups do electrons when reacting with other elements. In share similar properties with the metals in Group 14, only carbon is a nonmetal. What makes 14 carbon especially important is its role in the chemis- their group. 6 Teach Begin a table on the board with C try of life. Compounds made of molecules contain- ing long chains of carbon atoms are found in all properties of nonmetals as you did with Carbon living things. metals. Again, keep track of the properties of 14 Most of the fuels that are burned to yield energy each nonmetal family as students study Si Silicon contain carbon. Coal, for example, is mostly the ele- them. Record the properties of that group, 32 ment carbon. Gasoline is made from crude oil, a including the number of electrons lost when mixture of carbon compounds with chains of 5 to 50 reacting with other elements. Also include Ge Germanium or more carbon atoms in their molecules. examples of each. 50 Apply Ask: What property do elements in Sn mixed groups share? (They all gain, lose, Tin IGURE 82 F 22 or share the same number of electrons.) Carbon learning modality: visual Pb Charcoal is one form Lead of carbon, the only nonmetal in Group 14.