Question 1
In Cl₂ + 2Br⁻ → 2Cl⁻ + Br₂, which species is oxidised?
Need a hint for Question 1?
Compare the free halogen with the halogen in the halide.
Check Question 1
Bromide ions, Br⁻, lose electrons to form Br₂.
STUDENT SPACE · TOPIC 3
Halogens and displacement
Predict halogen displacement and explain the electron transfer.
The essentials
- The halogens are diatomic non-metals. Density increases down the group.
- A chlorine atom has configuration 2,8,7. It gains one electron to form Cl⁻, with configuration 2,8,8.
- Reactivity decreases down Group VII: chlorine is more reactive than bromine, then iodine.
Key vocabulary
| English | Chinese |
|---|---|
| halogen | 卤素 |
| halide ion | 卤离子 |
| displacement | 置换 |
Quick practice
Try each question before opening its hint or answer. Use paper for calculations and diagrams.
Question 2
Predict whether iodine reacts with potassium bromide solution. Explain.
Need a hint for Question 2?
Compare iodine with bromine in the reactivity order.
Check Question 2
No displacement. Iodine is less reactive than bromine.
Question 3
Write the ionic equation for chlorine reacting with iodide ions.
Need a hint for Question 3?
Chlorine gains electrons while iodide loses them.
Check Question 3
Cl₂ + 2I⁻ → 2Cl⁻ + I₂. Atoms and total charge balance.
Use Lesson 3 in your worksheet for written practice. Your teacher will discuss those answers in class.