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Please grab a handout from the front table!! Physical Science Atoms—Day 9 Materials Needed: Writing Utensil Folder Notebook Day 9 • Bell Work: What happens if an atom of Oxygen gains a electron? What happens if it loses an electron? What about if it gains a neutron? • Agenda: • Notes on Isotopes • Isotope Demo • Calculating Average Atomic Mass • Finish Isotope Lab/Exit Slip Q1: What is air pressure? A. It is the measure of the movement of the air molecules. B. It is the measure of the air molecules push on a surface. C. It is the measure of the amount of oxygen in the atmosphere. D. It is the measure of the amount of nitrogen in the atmosphere. S.C.8.4.3b DOK1 Q2: How are elements and compounds related? A. Elements and compounds are not related. B. An element can be broken down into compounds. C. A compound is two or more elements chemically combined. D. An element is two or more compounds chemically combined. SC8.2.1.a DOK 2 Mathematics Booster What is the percent by mass of each type of nut in can A? We calculated percentages for peanuts Can A = 44.19% Greek/Latin Greek/Latin Meaning pro in front of, first a- not, without tom cut, incision -ide a thing connected with or belong to iso same Picture Today’s Objectives • I will know how isotopes form. • I will be able to calculate the atomic mass of an element based on percentages of isotopes. Bell Work Answer • What happens if an atom of Oxygen gains a electron? What happens if it loses an electron? What about if it gains a neutron? A1: What is air pressure? A. It is the measure of the movement of the air molecules. Air molecules do not need to be moving in order to create pressure just like a stack of books on your head does not need to be moving in order to create pressure on your head. B. It is the measure of the air molecules pushing on a surface. Air is made up of many different components, mostly Nitrogen and Oxygen, that are pressing down on you like a stack of books. C. It is the measure of the amount of oxygen in the atmosphere. Oxygen is only a part of what makes up all of the air molecules pushing down on a surface. D. It is the measure of the amount of nitrogen in the atmosphere. Nitrogen is only a part of what makes up all of the air molecules pushing down on a surface. S.C.8.4.3b DOK1 A2: How are elements and compounds related? A. Elements and compounds are not related. Elements and compounds ARE related. It takes two or more elements chemically combined to make a compound. B. An element can be broken down into compounds. Elements cannot be broken down into compounds, but compounds can be broken down into elements through a chemical reaction. C. A compound is made out of two or more elements. Two or more elements chemically combine to make a compound. For example, CO2 (carbon dioxide). D. An element is made out of two or more compounds. Elements are not made out of compounds. SC8.2.1.a DOK 2 Can A Almonds 47.02 = 13.64% 344.79 Brazil Nut 57.88 = 16.79% 344.79 Cashew 46.20 = 13.40% 344.79 Hazel Nut 19.90 = 5.77% 344.79 Pecan 21.40 = 6.20% 344.79 • Math Talk: using the mass of the specific nut is divided by the total mass of all the nuts. That product is them multiplied by 100 to determine the percentage. Introduction to Isotopes • http://education-portal.com/academy/lesson/isotopesand-calculation-of-a-weighted-average.html#lesson Isotopes • Isotopes are atoms of the same element type that have different numbers of neutrons Neutrons have NO CHARGE, so they only change the mass of the atom . These are all atoms of hydrogen One way to show Isotopes: Carbon-12 Atomic Mass Protons Electrons Neutrons Carbon-14 Let’s Practice Oxygen has 3 isotopes: •oxygen-16 •oxygen-17 •oxygen-18 Oxygen-16 Oxygen-17 Oxygen-18 Atomic Mass Protons Electrons Neutrons • How many of each subatomic particle are in each of the isotopes of oxygen? A second way to show Isotopes 12 6 C 14 6 C Let’s Practice • Write the symbols for the following isotopes using isotope notation. 24 A.) Magnesium – 24 12 B.) Carbon – 13 13 C.) Silver – 108 6 Mg C 108 47 Ag Let’s Practice Calculate the number of protons, neutrons, and electrons in an atom of zirconium-90 that has no overall charge and an atomic number of 40. Answer Number of protons = atomic number 40 Number of neutrons = mass number – atomic number = 50 Number of electrons = number of protons = 40 What do you think? • Why is the atomic mass on the periodic table not a whole number? • http://phet.colorado.edu/en/simulation/isotopes-andatomic-mass Calculating the Mass of an Element • The atomic mass of an element is the weighted average of the masses of all the naturally occurring isotopes of that element. Calculating Atomic Mass Chlorine-35 makes up 76% of all the chlorine in nature, and chlorine-37 makes up the other 24%. What is the atomic mass of chlorine? Step 1: Multiply the mass number of each isotope by its percentage abundance in decimal form. (35 x 0.76) = 26.60 (37 x 0.24) = 8.88 Step 2: Add these amounts together to find the atomic mass. 26.60 + 8.88 = 35.48 amu Let’s Practice The metal thallium occurs naturally as 30% thallium-203 and 70% thallium-205. Calculate the atomic mass of thallium. (0.30 x 203 amu) + (0.70 x 205 amu) = 204.4 amu Let’s Practice Calculate the atomic mass of gallium, which consists of 60% gallium-69 and 40% gallium-71. (0.60 x 69 amu) + (0.40 x 71 amu) = 69.8 amu Solve the Following Problems 1. Calculate the atomic mass of boron, which occurs naturally as 20% boron-10 and 80% boron-11. 2. Calculate the atomic mass of rubidium, which occurs naturally as 72% rubidium-85 and 28% rubidium-87. 3. Calculate the atomic mass of silicon, which occurs naturally as 92% silicon-28, 5% silicon-29, and 3% silicon-30. Solutions 1. (0.20 x 10 amu) + (0.80 x 11 amu) = 10.8 amu 2. (0.72 x 85 amu) + (0.28 x 87 amu) = 85.56 amu 1. (0.92 x 28 amu) + (0.05 x 29 amu) + (0.03 x 30 amu) = 28.11 amu Isotope Activity • Work with your group to gather your data. Record your data in the first two columns. • DO NOT open the bags. • Complete the vocabulary and questions portion for next class. Homework • Atomic Changes Worksheet (1/2 sheet of paper) Exit Slip • Explain an isotope.