Students will learn that different carbon atoms always contain 6 protons but can contain different numbers of neutrons. These different atoms are called isotopes. This lesson will reinforce understanding of element symbol notation.
This lesson is a part of MEL Chemistry VR. Learn more →
atoms, electrons, nucleus, protons, neutrons, isotopes, mass number
- Isotopes are different elements because their nuclei are different.
- Confusion between mass number, atomic number, and atomic mass.
- Recall that an atom’s nucleus consists of positively-charged protons and uncharged neutrons
- Learn that protons and neutrons are much heavier than electrons
- Learn to interpret element notations, e.g. 126C, 146C
- See that atoms of the same element can contain different numbers of neutrons in their nuclei
- Learn how to calculate an atom’s mass number
Discussion of half-life concept.
Explore how radioactive isotopes decrease in quantity over time.
Students are given a cup of small grains (like rice) and are instructed to remove half of the remaining amount every 30 seconds.
History and sources of knowledge
- Soddy’s discovery of radioactive isotopes.
- Thomson’s discovery of stable isotopes.
- Modern methods of mass-spectrometry showing isotopic composition.
- Modern separation methods.
Topics to discuss
- Half-life concept.
- Why the number of neutrons in an atom does not affect its chemical properties.
- Atomic mass as average mass of different isotopes.
Fun facts and quotes
- You can accumulate heavy water (water that contains deuterium, a hydrogen isotope with one proton and one neutron) in your kitchen, if you don't replace the water in your kettle for a very long time and add more water as the water in the kettle evaporates.
- An isotopic analysis can not only tell you when organisms lived, but also what they ate and their migration paths.
- All synthetic elements only have unstable (radioactive) isotopes.
- Radiocarbon dating is used to determine the ages of once-living organisms (from millions of years old to thousands of years old).
- The origin of wine can be easily determined by the ratio of stable isotopes of the different elements in the wine.
- What distinguishes the atoms of one element from the atoms of another?
- Two atoms have the same number of neutrons but a different number of protons. Are they isotopes?
- Two atoms have the same number of protons but a different number of neutrons. Are they isotopes?
- What does the number 7 represent in the isotope 7Li?
- List the number of protons, neutrons, and electrons in this pair of isotopes: 4020Ca/4420Ca.
- Calculate the number of neutrons in the different isotopes of oxygen.
- Calculate the atomic mass from the percentage and mass of two isotopes (for example, for 35Cl/37Cl).
- Calculate the isotopic ratio (in percentage) from the mass-spectrum (for example, 63Cu/65Cu).
Please see below for the link to a Google form containing a quiz on the material above.
This can be assigned during class time or as homework. The quizzes are marked and the system shows which questions students get correct and incorrect. Please note that students should record their scores, as they will not be viewable later.