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Periodic Table Performance Indicator 7.P.2A.2 Essential Questions: 2. How are elements classified on the periodic table? Periodic Table Atom • The basic unit of a chemical element. (ex: gold, oxygen, mercury) • Consists of 3 basic parts. (protons, neutrons, electrons) • The atomic mass is the sum of the protons and neutrons. © KeslerScience.com Periodic Table Electrons • Negatively charged subatomic particle. • Located outside the nucleus. © KeslerScience.com Periodic Table Valance Electron • An electron in one of the outer shells of an atom that can participate in forming chemical bonds with other atoms. • The number of valance electrons determines the element’s reactivity. © KeslerScience.com Periodic Table Periodic Table • The periodic table is used to organize all of the elements. • Every periodic table will have a square for each element with the element name, chemical/element symbol, atomic number, and atomic mass. © KeslerScience.com Quick Action – INB Template 1. Cut out the INB Template. 2. Complete the blanks with words from the following slide. 3. Paste tab in your notebook. © KeslerScience.com 14 Si 28.086 Silicon ______________________ ______________________ ______________________ ______________________ ______________________ ______________________ Periodic Table What can we tell about this element (atom) from the periodic table? 1. The atomic number(14), which is also the number of protons. 2. The symbol for nitrogen. (Si) 3. The atomic mass. (28.0086) 4. The element’s (atom’s) name. (Silicon) © KeslerScience.com 14 Si 28.0086 Silicon Periodic Table Chemical/element symbols oEach element has a different symbol oSymbols are written with one, two, or three letters. oThe first letter is always capitalized oStudents should be familiar with following element names and symbols: © KeslerScience.com © KeslerScience.com Element Symbol Element Symbol Hydrogen Carbon Nitrogen Oxygen Chlorine Magnesiu m Zinc Calcium Phosphorus H C N O Cl Mg Silicon Copper Aluminum Silver Gold Iron Si Cu Al Ag Au Fe Zn Ca P Helium He Potassium K Sodium Na Periodic Table Atomic Number • The atomic number of an element is equal to the number of protons. • The atomic number is a whole number • The atomic number is always the same for a given element. • The elements on the periodic table are arranged numerically by increasing atomic number. © KeslerScience.com Periodic Table Atomic Mass • The atomic mass is an average sum of the number of the protons and the number of neutrons in the nucleus of the atom. • Since the atomic mass of an element is an average, it is usually not a whole number. © KeslerScience.com Periodic Table Periods • A horizontal row on the periodic table is called a period. © KeslerScience.com Periodic Table Families • Families, also called groups, are vertical columns of elements on the periodic table • They are numbered 1-18 • Elements in the same family have similar properties © KeslerScience.com Metals, Nonmetals and Metalloids Periodic Table Classification: Metalloids (green) • There is a zigzag line on the right side of the periodic table that separates the metals from the nonmetals. Metalloids are found along this zigzag line. • Elements identified as metalloids have properties (characteristics of both metals and nonmetals © KeslerScience.com Metals, Nonmetals & Metalloids Periodic Table Periodic Table Classification: Metals (blue) properties: • Metals are generally located on the left side of the zigzag line. • Examples of metals are: Sodium (Na), Calcium (Ca), Iron (Fe), and Aluminum (Al). • The majority of elements are metals. © KeslerScience.com Metals, Nonmetals & Metalloids Periodic Table and Reactivity Periodic Table Classification: Nonmetals (red) properties: • Nonmetals with the exception of Hydrogen (H), are located on the right side of the zigzag line on the periodic table. • Examples of nonmetals are: Chlorine (Cl), Oxygen (O), Sulfur (S), and Iodine (I). © KeslerScience.com Metals, Nonmetals & Metalloids Quick Action – Match the words with the definition With a partner match the classification with the object. 1. Metal 2. Nonmetal 3. Metalloid © KeslerScience.com A. B. C. D. E. Shiny new Yeti cup Carbon in your pencil lead Yellow glob of sulfur Nitrogen in the air Silicon used in microprocessors in cell phones F. Helium in a balloon G. An aluminum can STOP © KeslerScience.com Quick Action – INB Template Periodic Table INB - Let’s add some more information to your periodic table on the upcoming slides. © KeslerScience.com Quick Action – INB Template Trends on the Periodic Table 2 • Elements in Period 3 have 3 orbitals • Elements in Period 7 have 7 orbitals • Moving down the Period increases the reactivity • Cs is more reactive than K • Li is less reactive than Na • Draw a down arrow next Period 1-7 and put the words “increasing energy and reactivity.” © KeslerScience.com Increasing energy and reactivity • Moving down the Period (Rows 1-7) the number of energy levels or shells increases by 1. 1 Quick Action – INB Template • IA Group has one valance electron. • 5A Group has five valance electrons. • Copy the notes and orange arrow. © KeslerScience.com 2 Increasing energy and reactivity Trends on the Periodic Table • Groups (Columns 1-18) – elements have the same number of valance electrons in each group. • Valance electrons are the electrons in the outer energy level (shell). Same# of valance electrons going down the column 1 Quick Action – INB Template Trends on the Periodic Table • Reactivity increases as you move from right to left across the periodic table. Same# of valance electrons going down the column 1 Increasing energy and reactivity • Draw an arrow indicating “increasing reactivity.” 2 Increasing reactivity © KeslerScience.com Periodic Table and Reactivity Reactivity of atoms • The ability of atoms to combine or separate with other atoms to create new substances (chemical reaction) • Valance electrons are the key to this process. • Reactivity changes across the periodic table. © KeslerScience.com Quick Action – Group PT Model 1. Assign four students to each be a different atom from Period 2. 2. Have the four students come up in front of the class and “act out” their level of reactivity based on their position on the periodic table. 3. Notice the differences in their reactivity and how it relates to the periodic table. © KeslerScience.com Periodic Table and Reactivity What makes an atom “happy” (stable) • Having its outer energy level (shell) filled with electrons. • Example: (8A) highlighted in red. • These atoms do not want to bond with other atoms. (inert) • Helium is the exception because it is “happy” (stable) with only two valence electrons. © KeslerScience.com 8A Periodic Table and Reactivity What happens if an atom doesn’t have 8 valence electrons? • Hydrogen has only one valance electron. (Group 1A). • Does not follow the rule of 8, but its “happy” number is 2. Who might hydrogen bond with to make itself “happy (stable)?” © KeslerScience.com Hydrogen Periodic Table and Reactivity Hydrogen easily bonds with itself! This way both hydrogen atoms can share an electron and be “happy (stable).” © KeslerScience.com Hydrogen Hydrogen Periodic Table and Reactivity Let’s look at oxygen? Oxygen has six valence electrons (It’s in Groups 6A.) It needs to bond with one atom that either has two valance electrons, or two atoms that have one valance electron. © KeslerScience.com Oxygen Periodic Table and Reactivity • Now oxygen is “happy” (stable). Hydrogen Hydrogen • It bonded with 2 hydrogen atoms making a molecule of H20 (water). • Sometimes called the Mickey Mouse Molecule. Oxygen © KeslerScience.com Check for Understanding Can you… 1. Identify that valence electrons determine an atom’s chemical properties, including reactivity. 2. Interpret the arrangement of the periodic table to explain how properties are used to classify elements, including periods and groups. © KeslerScience.com