Group 17 halogens – color, state and oxidizing power
ChemistryInorganic ChemistryAges 15–16
Use it with your class: students open it from a link or a QR code, with no account needed.
Next in Inorganic Chemistry
Pick F₂, Cl₂, Br₂ or I₂ and drag the temperature slider: the vessel shows the element's real color and physical state at that melting/boiling point. Press Run reaction to let the halogen react with red-hot Fe, with H₂, or with NaCl, NaBr, NaI solution: the simulation shows whether the reaction happens, what conditions it needs, the chemical equation, and the resulting solution color. Students see oxidizing power decreasing F₂ > Cl₂ > Br₂ > I₂, and a stronger halogen displacing a weaker one from its salt.
Lesson: Group 17 elements: physical properties, oxidizing power, and reactions with metals, hydrogen, and halide salt solutions
What it shows
Down Group 17 the halogens show clear trends. Melting and boiling points rise from F₂ to I₂ because larger molecules have stronger London dispersion forces, so at room temperature fluorine and chlorine are gases, bromine is a liquid and iodine is a solid. Oxidizing power falls in the same direction as the atoms get larger and attract electrons less strongly: F₂ explodes with hydrogen even in the dark, while H₂ + I₂ is slow and reversible. A more reactive halogen displaces a less reactive one from its halide salt, confirming the order F₂ > Cl₂ > Br₂ > I₂.
How to use
Select a Halogen and drag the Temperature slider to watch it melt, boil or sublime at its real melting and boiling points. Then choose a Reactant, such as red-hot iron, hydrogen or a sodium halide solution, and press Run reaction. Record whether a reaction occurs, the conditions it needs and the color of the solution, then build the order of oxidizing power from the results.
Parameters you can change
- Halogen Fluorine F₂, Chlorine Cl₂, Bromine Br₂, Iodine I₂
- Reactant Fe (red-hot iron wire), H₂ gas, NaCl solution, NaBr solution, NaI solution
- Temperature -200–600 °C
- Animation speed 0.5–3 ×
Questions to explore
- Why do the boiling points of the halogens increase from F₂ to I₂?
- Does Br₂ react with NaCl solution or with NaI solution, and how does oxidizing power explain the result?
- Which halogen reacts most violently with hydrogen, and what conditions does iodine need to react?
