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Student Resource Sheet AC - 12 IT’S ELEMENTARY! You have learned that there are over 109 naturally occurring elements and a growing list of manmade elements. With so many different elements combining to make a countless number of compounds, this task can seem overwhelming. As a result scientists have found a way to organize these elements based on similar characteristics. Elements are organized on the Periodic Table of the Elements. By knowing how the periodic table is organized, you can make predictions about the properties of these elements and their ability to form the compounds in our world. Objective: When you have completed this investigation, you should be able to 1. Interpret the layout of the periodic table in order to explain how it is organized. Materials: Periodic Table of the Elements Activity 1: Atoms and the Periodic Table USING THE PERIOIDIC TAB LE Scientists all over the world use the same symbols for the elements. Chemical symbols are a shorthand way of writing the chemical names of the elements. Symbols for the elements usually consist of one or two letters. Some man-made elements have three letters in their chemical symbols. If the chemical symbol is just one letter, that letter is a capital letter. If the symbol has two or more letters, then the first letter is a capital and the following letters are lower case. This standard for writing symbols for the elements makes it easy for scientists to identify the specific elements. In addition to having a chemical symbol, each element has an atomic number. The atomic number is the number of protons in an atom’s nucleus. This number is also usually equal to the number of electrons in the atom as well. The atomic number is a unique property that identifies an element. No two elements have the same atomic number. Elements are arranged on the Periodic Table according to their atomic number. Atomic numbers increase as you read the elements from left to right. Another important property of elements is atomic mass. Atomic mass is equal to the number of protons and number of neutrons in an atom. Since electrons are so small, their mass is not figured into the atomic mass. The atomic mass that appears on the periodic table is the average mass of an element’s atoms. Atomic mass increases with atomic number. 1. Read, “Using the Periodic Table.” 2. Reread the article and highlight important information about the elements and their placement on the periodic table. AC - 99 Student Resource Sheet AC - 12 3. What method do scientists use when coming up with chemical symbols? __________________________________________________________________________ __________________________________________________________________________ 4. Study the key in Figure 1, “Element Key.” Figure 1: Element Key Atomic Number 8 O Element Name 5. Atomic Mass 15.9994 Chemical Symbol Oxygen Use the key and the information from the text to complete Chart 1, “Elements of the Periodic Table.” Chart 1: Elements of the Periodic Table Element Name Chemical Symbol Atomic Number Atomic Mass Hydrogen Na 17 Copper 4.00 6. Describe a pattern that exists between the atomic number and the atomic mass. _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ If an atom has 15 protons, what conclusions can you make about the element’s atomic number? What would this element be? _____________________________________________________________________________ 7. _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ AC - 100 Student Resource Sheet AC - 12 Activity 2: Chemical Patterns 8. Study the element resource cards provided by your teacher. 9. Find the elements that are gases at room temperature. List the elements that are gases: ________________________________________________________________________ On which section of the periodic table are these elements located? ________________________________________________________________________ ________________________________________________________________________ 10. Find all of the elements that have the words “silver” and “metal” in their description. List the elements: ________________________________________________________________________ On which section of the periodic table are these elements located? ________________________________________________________________________ ________________________________________________________________________ 11. Find all of the elements with 7 outer electrons. List the elements: _______________________________________________________________________ In what way are these elements grouped? _______________________________________________________________________ _______________________________________________________________________ 12. Read, “It’s Elementary.” Analysis Describe how the properties of an element can be determined based upon the element’s location on the periodic table. Use specific examples and evidence from the investigation to support your response. _____________________________________________________________________________ 1. _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ AC - 101 Student Resource Sheet AC - 12 IT’S ELEMENTARY All of the elements are organized on the Periodic Table of the Elements. At first glance, the periodic table may not make much sense to you. However, knowing how to read the Periodic Table of the Elements can provide you with important information about each element. On the right side of the periodic table, you will notice a zigzag line (See Figure 1). This line is very important in distinguishing among elements. All of the elements that are located to the left of this zigzag line are considered to be metals. Elements that are to the right of the zigzag line are considered to be nonmetals. Metals and nonmetals have very different properties. As a result, metals and nonmetals will combine to form Group Figure 1 new substances. In addition to the zigzag line, the periodic table contains vertical columns of elements as well as horizontal rows of elements. The vertical columns are called Period groups. There are eighteen groups of elements (See Figure 1). Within each group, the elements have similar but not identical properties. These properties are determined by the valence electrons for an element’s atoms. Valence electrons are the outermost electrons of an atom. The electrons are important because they are involved in the chemical bonding of elements to make compounds. As a result, these electrons help to determine the properties of the elements in a group. All of the elements in a given group have the same number of valence electrons. For example all of the elements in Group 1 or IA have one valence electron. This characteristic gives the elements in the family similar properties. In general, all metals have 1, 2, or 3 valence electrons. Nonmetals will have 4, 5, 6, 7, or 8 valence electrons. Lastly, there are seven horizontal rows or periods (See Figure 1) on the periodic table. Unlike the elements in each family, the elements in each period do not share common properties. The properties of the elements change dramatically across any given period. However, there is still a pattern to the periods of elements. The first element in a period is always an extremely active metal. The last element in a period is always an inactive gas. For example, in period 3, sodium (Na) is an active metal while argon (Ar) is a stable, non-reactive gas. AC - 102