Though John Dalton postulated that all atoms of an element are identical, scientists now know that isotopes, or different versions of each element, exist in nature. A Frayer Model is a perfect tool to deepen the understanding of isotopes. In this activity, students will define what isotopes are, illustrate important characteristics, and provide both examples and non-examples.
Isotopes are atoms of an element that differ in their number of neutrons. Because the identity of an atom is defined by its atomic number, as long as the atoms have the same number of protons, the atoms are the same element. Just as apples can be different sizes, atoms can also be heavy or light, even when they are the same element. Boron, for example, is found in nature as atoms with a relative mass of 10 amu (5 protons and 5 neutrons) or 11 amu (5 protons and 6 neutrons). In a sample of boron, around 20% of the atoms would have a mass of 10 amu and 80% would have a mass of 11 amu.
Extended Activity
Have students create a narrative storyboard or a timeline that illustrates the discovery of certain isotopes for a chosen element. Students should include the scientists involved and the process by which each isotope was discovered. This extension is a perfect way for students to further understand how continued research in science is constantly evolving things we already know.
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Student Instructions
Create a frayer model that defines and illustrates what isotopes are (and aren't!).
Design a simple lab activity where students use common objects (like colored candies or beads) to model isotopes. Assign each color to represent a proton, neutron, or electron, and have students build different isotopes of an element. This tactile approach makes the idea of varying neutrons in isotopes memorable and fun.
Connect isotopes to everyday items students know, such as apples of different sizes or coins with different years. Highlight that while the item stays the same, certain details (like weight or date) can vary—just as isotopes have the same protons but different neutrons. This helps students internalize the definition of isotopes quickly.
Encourage students to sketch atom diagrams showing protons and neutrons in the nucleus. Label each part clearly and vary the number of neutrons for each isotope. Visualizing these differences supports deeper understanding and reinforces science vocabulary in context.
Lead a conversation about how isotopes are used in medicine, archaeology, and environmental science. Ask students to brainstorm examples like carbon dating or medical imaging. This real-world tie-in boosts engagement and shows the relevance of isotopes in daily life.
End the lesson by having each student write down one thing they learned about isotopes and one question they still have. Collect these tickets to gauge understanding and plan future lessons that address gaps or spark curiosity.
An isotope is an atom of the same element that has a different number of neutrons, meaning it has the same number of protons but a different atomic mass.
Use relatable examples, like comparing atoms to apples of different sizes—both are apples but can weigh more or less. Explain that isotopes have the same number of protons but different numbers of neutrons, changing their mass but not their element.
A Frayer Model is a graphic organizer with sections for definition, characteristics, examples, and non-examples. It helps students clearly understand isotopes by organizing information visually and encouraging deeper thinking.
Examples of isotopes include Boron-10 and Boron-11 (both boron, but with different neutron counts). Non-examples would be atoms of different elements entirely, like boron and carbon.
Have students complete a Frayer Model for isotopes, filling in the definition, characteristics, examples, and non-examples, and drawing illustrations for each. This makes the concept interactive and memorable.