This lesson plan examines the properties of elements and the periodic table. Students learn the basic definition of an element and the 18 elements that build most of the matter in the universe. The periodic table is described as one method of organization for the elements. The concepts of physical and chemical properties are also reviewed.

Engineers use the properties of matter to decide what materials to use when creating and building things. For example, metals have certain properties that allow them to bend or not bend, to expand and contract, and to hold certain amounts of weight. Engineers also use the chemical properties of different elements to develop mixtures and substances for new medicines and products. physical property chemical property element periodic table atom isotope electron proton neutron atomic number atomic theory Students should know the basic properties and structure of the atom. Distinguish between physical and chemical properties. Describe the arrangement of elements in the Periodic Table of Elements. Describe how engineers use knowledge of the physical and chemical properties of elements when choosing materials for products. We want to learn more about the properties of a substance or object, so we can determine what tools and materials to use when building or creating things as engineers. For example, the properties of crayons and markers are different, yet they both produced color. What are the properties of a crayon? (Write the answers on the board. Possible answers: hard, dry, waxy texture, melts, different colors, etc.) Okay, what are the properties of a marker? (Write the answers on the board in a new list. Possible answers: smooth tip, sweet smelling, sour smelling, different colors, wet, etc.) We decide whether we are going to use a crayon or a marker when coloring a picture, depending on the end result that we want. The end result is also how engineers choose which materials they will use to design something. The properties of a substance can be separated into two categories: Physical and chemical. Physical properties are those that can be observed in an object such as size, shape, color, even the boiling point. Chemical properties are the ability to combine with another substance and make a new substance such as when water and iron combine to make rust. Are the properties we have listed physical properties or chemical properties? They are physical properties because they do not change into something else. Both physical and chemical properties are based on the behaviors of the elements that make up the object. An element is something that is made of the same kind of atoms, which are made up of protons, electrons and neutrons. For example, the element lead is made up of all lead atoms, nothing else. There are over 100 elements that exist, but only 18 elements that make up most of the known universe. Some of these 18 elements you may have already heard of, including hydrogen, helium, carbon, oxygen, nitrogen, sodium, magnesium, phosphorus and sulfur. Can you think of anything that has one of those elements or a combination of those elements in it? Well, water and air are both made of some of the elements that we just listed. In fact, hydrogen makes up 90% of all matter in the universe. Carbon is an element found in all things that are living. The elements can be arranged in many ways: however, the most common way is in the periodic table. Elements are arranged in the periodic table based on their properties (both physical and chemical, although mostly chemical). The periodic table organizes elements based on two major things: the number of shells an element has for its electrons determines the rows (periods) where the element is placed, and the number of electrons in the outer most shell of the element determines the column (group) where the element is placed. The period or group that the element is placed in tells us a lot about the properties of that element. We are going to learn more about that today. Engineers utilize materials' physical and chemical properties when designing almost anything, including buildings and new medicines. Engineers want to design buildings that are strong. They also want to design medicine to be both safe and effective. For example, metals have certain properties that allow them to bend or not bend, to expand and contract, and to hold certain amounts of weight. If an engineer were building a bridge over a river, they would want to choose a metal that would be strong, and somewhat flexible. However, they would want to make sure not to choose a metal that expands or contracts too much in different types of weather. If a bridge grew or shrank too much in size, for example, it could collapse causing severe injury and damage to surrounding structures. Matter is often defined by physical properties. Physical properties are attributes that can be observed in an object. Some examples of properties include color, odor, size, weight, texture, buoyancy, boiling point, melting point, freezing point and shape. Matter is also defined by chemical properties. These are attributes that affect the chemical state of matter. For example, one chemical property may be the ability to combine with another element in a chemical reaction. An element is a substance that cannot be broken down by chemical reactions. The smallest particle of an element is the atom, which is made up of protons, electrons and neutrons. For example, the pure element gold is made of gold atoms and nothing else. If you add or subtract a proton from the nucleus of an atom, you create an entirely new element. For instance, if you subtract one proton from an atom of gold, you have platinum. If you add or subtract a neutron from the nucleus of an atom, then a new element is not created, instead you create a new isotope. Carbon-14 is an isotope of carbon, has two extra neutrons, and is radioactive and used for carbon dating. Over 100 elements have been discovered or created, but this lesson will focus on the first 18, which make up most of the matter in the universe. The lightest elements are hydrogen and helium. Hydrogen is also thought to be the first element that appeared on Earth. Currently, there are over 20 elements that are not derived naturally, but have been artificially synthesized by humans. Elements can be categorized in many ways, including name, symbol, atomic number, atomic mass, boiling point and melting point; however, the most common chart of the elements is the periodic table, which organizes the elements by chemical properties. Figure 1 lists the first 18 elements in the periodic table. The periodic table was first derived in 1869 by chemist Dimitri Mendeleev. It is a chart of the known elements that is organized like a big grid with rows and columns. The elements are placed in rows, called periods, because of their similar characteristics. All of the elements in a period have the same number of shells for their electrons. Elements in the top row have one shell, second row two shells and so on down the table for a maximum of seven. The elements are also placed in columns, or groups, that have the same number of electrons in their outer shell. Elements in the first column have one electron in their outer shell, second column two electrons and so on. There are some special groups on the periodic table, including the noble gases in group 18 (or 8, if not counting the transition elements) that have full outer valence shells. This means that they do not need any electrons to complete the shell and therefore are highly un-reactive. Also, the halogens in group 17 (or 7) are all missing one electron to fill their outer shell. All of these elements bond with hydrogen to form acids, such as hydrochloric acid. Characteristics of matters that affect the chemical structure of matter. Substance that cannot be broken down by chemical reactions. Any atoms of a chemical element with the same atomic number and nearly identical chemical behavior but with different number of neutrons in the nucleus. Characteristics of matter including boiling points, melting points, freezing points, density, color and smell. Engineering and the Periodic Table Today, we talked about the physical and chemical properties of elements and how these are important to engineers. Who remembers what the difference is between physical and chemical properties? Well, physical properties are those that can be observed in an object, such as size, shape, color and even boiling point or density. Chemical properties have to deal with the chemical state of the object, such as its ability to combine with another substance in a reaction. We also learned that elements are arranged in the periodic table based on physical and chemical properties (although mostly chemical). The way the elements are arranged in rows and columns on the periodic table helps tell us more about them. It is important that engineers use their knowledge about the properties of both elements and materials when creating new technologies. Let's pick one item in this classroom and list its properties. Imagine what that object would be like if it were constructed using entirely different materials. That is what engineers might do when creating a design that improves on an existing technology. Discussion Question: Ask a discussion question to get students to think about the upcoming lesson. After soliciting answers, explain that these questions will be answered during the lesson. What is an atom? (Answer: The basic building blocks of matter. Every atom consists of negatively-charged electrons and a nucleus made of positively-charged protons and neutrally-charged [neither positively- nor negatively-charged] neutrons.) Name one atom you might find in this classroom. Define It: In small groups, have the students engage in open discussion. Remind students that all ideas should be respectfully heard. Ask the students: How would you describe a "property" of an object? (Answers will vary. Possible answers include: smells, odorless, sticky, large, small, red, etc.) Vocabulary: Ask the students to write down the following vocabulary words on a sheet of paper or in their science journals and then develop their own definitions of these words based on what they have learned so far. Words to use: Element (Substance that cannot be broken down by chemical reactions.) Physical property (Characteristics of matter including boiling point, melting point, freezing point, density, color and smell.) Chemical Property (Characteristics of matters that affect the chemical structure of matter.) Engineering Redesign Similar to the lesson closure, have the students (as engineers) each pick an item in the classroom (whiteboard, chair, table, etc), and design an item that can replace it using different materials than that of which the item is currently constructed. Have the students list the benefits of their design and decide if their replacement is better than the original. Remind students that engineers often redesign items that already exist to make them work better. Research: Assign each student a different element from the periodic table (preferably from the first 18), and have them research where that element is present (i.e., what objects in the classroom are made up of the element, etc). Have students count how many rows down in the periodic table their element is to see how many shells the elements have for their electrons. Have students count the columns from the left in the periodic table their element is to see how many electrons are in the outer shell of the elements. The First 18 Elements: Students can quiz themselves about the first basic 18 elements using the interactive Periodic Table at FunBrain at: http://www3.funbrain.com/cgi-bin/pt.cgi?A1=s&A2=1&ACOMMON=1&submit=Play+Proton+Don Other Element Games: Students can play the element games at Jefferson Lab at: http://education.jlab.org/indexpages/elementgames.html. Pearson Education, Inc., Family Education Network, "Proton Don," accessed August 31, 2006. http://www3.funbrain.com/cgi-bin/pt.cgi?A1=s&A2=1&ACOMMON=1&submit=Play+Proton+Don Thomas Jefferson National Accelerator Facility - Office of Science Education, Science Education, Games & Puzzles, "Element Games," accessed August 31, 2006. http://education.jlab.org/indexpages/elementgames.html U.S. Department of the Interior, U.S. Geological Survey, Publications Warehouse, August 16, 2006, accessed September 12, 2006. http://pubs.usgs.gov/circ/c1143/html/fig9.jpg Winter, Mark, The University of Sheffield, "WebElementsTM Periodic Table Scholar Edition," accessed September 12, 2006.