This how it works covers Why Each Metal Produces a Different Colour within Flame Tests for GCSE Chemistry. Revise Flame Tests in Chemical Analysis for GCSE Chemistry with 22 exam-style questions and 15 flashcards. This is a high-frequency topic, so it is worth revising until the explanation feels precise and repeatable. It is section 5 of 13 in this topic. Use this how it works to connect the idea to the wider topic before moving on to questions and flashcards.
⚙️ Why Each Metal Produces a Different Colour
The colours arise from electron transitions in the metal atoms. Here is the sequence:
- Absorption (excitation): Heat from the Bunsen flame gives energy to electrons in the metal atoms. The electrons absorb this energy and jump to a higher energy level.
- Emission: The excited electrons are unstable. They quickly fall back down to their original (ground state) energy level.
- Light released: When electrons fall back down, they release the absorbed energy as light. The wavelength (colour) of the light emitted corresponds exactly to the energy difference between the two levels.
- Element-specific: Each element has uniquely spaced electron energy levels. Therefore each element emits light of specific, characteristic wavelengths — a unique colour "fingerprint".
Lithium's electron energy gaps produce red light (longer wavelength, lower energy). Copper's energy gaps produce green/blue light (shorter wavelength, higher energy). Sodium's gaps produce intense yellow-orange — so intense that even tiny traces of sodium contamination can mask other colours, which is why the wire must be scrupulously cleaned.
Practice questions for Flame Tests
Which type of wire is used to carry out a flame test?
Explain why different metal ions produce different colours in flame tests.