Students will zoom inside a sodium chloride crystal and explore its "atoms." They will see that the sodium atoms are missing one electron, while the chlorine atoms have one additional electron. In this way, students will explore the concept of ions.
This lesson is a part of MEL Chemistry VR. Learn more →
atoms, ions, charged particles, electrons, anions, cations
- Learn that there are substances that consist not of atoms, but of ions
- Find out how ions are formed
- See that the size of an atom and its ion are different
- Learn that ions can be positive or negative
The aim is to show students that dissolving table salt in water produces charged particles able to complete an electrical circuit.
Demonstrate that pure water doesn't conduct electricity. Add a pinch of table salt and note that the solution starts to conduct electricity. (Make a 10:1 consequential dilution to see when the solution stops conducting electricity). N.B. Tap water contains ions and will conduct electricity; distilled water is best for this experiment.
History and sources of knowledge
- Faraday’s discovery of unknown “species” that travelled from one electrode to the other in aqueous media. He thought that these species were generated by electrical current.
- Dissociation theory by Svante Arrhenius (Nobel Prize 1903). Ions form when crystalline substances are dissolved in water.
Topics to discuss
- Why is a sodium atom much bigger than a sodium ion?
- Why is a chloride atom smaller than a chloride ion?
- Substances are electrically neutral. There are no charged substances, but there are charged particles forming electrically neutral substances.
Fun facts and quotes
- Calcium, sodium, and potassium ions are vital for your body to function properly. In addition to other important functions, they greatly affect how your heart works and your thinking process.
- Neon lights glow because of the formation of neon ions inside the lamp. Different noble gases can be used to create different colors (helium: orange, neon: orange-red, argon: violet, krypton: off-white, xenon: blue).
- Ion engines can be used to move a spaceship in space (xenon ions).
- The smallest ion is the hydrogen ion, which is actually just a proton. It's about 2,000 times smaller than a hydrogen atom.
- How can you form an anion (a negatively-charged ion) from an atom?
- How can you form a cation (a positively-charged ion) from an atom?
- Which is greater for a negatively-charged ion, the number of electrons or the number of protons?
- Which is greater for a positively-charged ion, the number of electrons or the number of protons?
- How many protons, electrons, and neutrons does Li+ have?
- How many protons, electrons, and neutrons does F- have?
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.