Ohio Resource Center
Isotopes of Pennies
9, 10, 11, 12
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Professional Commentary

The purpose of this lesson is to demonstrate that isotopes of an element have different masses; that isotopes are atoms of the same element that have different numbers of neutrons; and that atomic mass is the weighted average of the naturally occurring isotopes of an element. This lesson helps students build their understanding of the properties of matter; specifically, it will help them understand that average atomic mass is not a simple average, but is weighted according to percent abundance. Before working on this lesson, students should be familiar with the periodic table and should have had some basic instruction in the following concepts: isotopes, mass number, and atomic number. Students should be able to describe an atom and its basic structure. (author/ts)

Ohio Science Academic Content Standards (2002)
Physical Sciences
Benchmarks (9–10)
Describe that matter is made of minute particles called atoms and atoms are comprised of even smaller components. Explain the structure and properties of atoms.
Benchmarks (11–12)
Explain how variations in the arrangement and motion of atoms and molecules form the basis of a variety of biological, chemical and physical phenomena.
Grade Level Indicators (Grade 9)
Recognize that all atoms of the same element contain the same number of protons, and elements with the same number of protons may or may not have the same mass. Those with different masses (different numbers of neutrons) are called isotopes.
Grade Level Indicators (Grade 11)
Explain that elements with the same number of protons may or may not have the same mass and those with different masses (different numbers of neutrons) are called isotopes. Some of these are radioactive.
Scientific Inquiry
Benchmarks (9–10)
Participate in and apply the processes of scientific investigation to create models and to design, conduct, evaluate and communicate the results of these investigations.
Benchmarks (11–12)
Make appropriate choices when designing and participating in scientific investigations by using cognitive and manipulative skills when collecting data and formulating conclusions from the data.
Grade Level Indicators (Grade 9)
Develop oral and written presentations using clear language, accurate data, appropriate graphs, tables, maps and available technology.
Draw logical conclusions based on scientific knowledge and evidence from investigations.
Grade Level Indicators (Grade 10)
Use mathematical models to predict and analyze natural phenomena.
National Science Education Standards
Science as Inquiry
Abilities necessary to do scientific inquiry (Grades 9 - 12)
Understandings about scientific inquiry (Grades 9 - 12)
Physical Science
Structure of atoms (Grades 9 - 12)