Cambridge IGCSE Chemistry · Syllabus 0620 · The Periodic Table
Halide Ion
What is Halide Ion?
The negative ion formed when a halogen atom gains one electron, giving it a full outer shell and a charge of one minus. Chloride, bromide and iodide ions are single ions written as Cl minus, Br minus and I minus, and in aqueous solution they are colourless, unlike the halogens themselves.
This definition is part of the The Periodic Table chapter in Cambridge IGCSE Chemistry.
Common mistakes with Halide Ion
- Error 14 · “Potassium bromide solution is red-brown.” Defect The colour of the element attributed to its ion. Chemistry Halide ions in solution are colourless. Red-brown is the free element bromine. This matters because the colourless starting solution is what makes a displacement visible. Repair Halide solution \(=\) colourless. Halogen in solution \(=\) coloured. Transfer What colour is aqueous potassium iodide? Colourless.