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The flame test colours are lithium crimson, sodium yellow, potassium lilac, calcium orange-red and copper green. Free notes and 11 questions answered.
Flame Tests for Metal Ion Identification is part of Identification of ions by chemical and spectroscopic means (chemistry only) in GCSE AQA Higher Chemistry.
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GCSE AQA Higher
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The flame test colours are lithium crimson, sodium yellow, potassium lilac, calcium orange-red and copper green. Free notes and 11 questions answered.
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Use this lesson to stay inside Identification of ions by chemical and spectroscopic means (chemistry only) while connecting the detail back to the wider Topic 8: Chemical analysis topic.
Read the core explanations from Flame Tests for Metal Ion Identification before testing yourself from memory.
Drop a pinch of table salt into a gas flame and watch it turn bright yellow. Add some copper wire and the flame glows green. This is a key scientific idea - it is chemistry revealing the identity of metal ions through light.
When metal compounds are heated strongly, their electrons absorb energy and jump to higher energy levels. As these excited electrons fall back down, they release energy as light of specific colours. Each metal produces its own unique colour signature — like a fingerprint made of light.
This technique works because electrons in different metals have different energy gaps between their levels. When they fall back down, they emit light of different wavelengths — and wavelength determines colour.
Five metal ions produce distinctive colours that you must memorise for your exam. These aren't random — they're the most common metals that give clear, unmistakable colours.
Lithium compounds: Crimson (deep red)Sodium compounds: Yellow (bright golden)Potassium compounds: Lilac (pale purple)Calcium compounds: Orange-red (brick red)Copper compounds: Green (blue-green)
Notice the pattern: Group 1 metals (lithium, sodium, potassium) give warm colours, while Group 2 calcium gives orange-red. Copper, a transition metal, produces the distinctive green that's completely different from the others.
Getting accurate results requires clean equipment and proper technique. Contamination from previous tests will give false colours — especially sodium, which is everywhere and produces such a bright yellow it masks other colours.
Worked example: Flame Test Method
Identify an unknown metal compound using flame test
Answer: Compare observed colour to known standards to identify the metal ion
The nichrome wire is crucial because it contains metals that don't produce visible flame colours. Steel wire would interfere with results. Some labs use wooden splints soaked in the compound, but wire gives more consistent results.
Flame tests have a major limitation: they can't identify metals in mixtures. If your sample contains both sodium and potassium, you'll see the bright yellow sodium colour but miss the pale lilac potassium completely.
This happens because some colours are much brighter than others. Sodium yellow is so intense it overwhelms almost everything else. Even tiny amounts of sodium contamination will mask other metals present.
Other limitations include: some metals produce similar colours that are hard to distinguish, the test is qualitative only (tells you what's there, not how much), and it only works for metals that produce visible light when heated.
Exam questions often show you flame colours and ask you to identify the metal, or give you a scenario where flame tests are used in analysis. The key is matching colours precisely to the five you must know.
Watch out for these common exam traps: confusing lithium crimson with calcium orange-red (lithium is deeper red), thinking flame tests work for mixtures (they don't — bright colours mask pale ones), and forgetting that the test identifies the metal ion, not the compound itself.
For 6-mark questions about analytical methods, structure your answer: state what flame tests can do (identify specific metal ions), explain the method briefly, give the colour results, then evaluate limitations (mixtures, contamination, qualitative only).
Exam precision note: In Flame Tests for Metal Ion Identification - Flame tests - Identification of ions by chemical and spectroscopic means (chemistry only), always identify the key chemical idea first, then link it to evidence, data, or an equation. A high-scoring GCSE answer names the particles involved, states what changes, and justifies the conclusion using correct scientific language. Where calculations are used, show each step with units and keep significant figures sensible. Finally, check that terminology matches AQA wording so your answer is unambiguous and mark-scheme friendly.
For AQA GCSE, the five flame-test colours to know are lithium crimson, sodium yellow, potassium lilac, calcium orange-red, and copper green. Students should not be expected to learn colours for additional ions such as barium in this specification point. A good answer links the observed colour to the presence of a particular metal ion rather than to the metal atom in general.
Published by Revise Right. Use the official specification reference to check the requirements for your course. Content updated: 2026-03-25.
Move to the related lessons or back to the topic page when you need the wider sequence before exam-style practice.
The flame test colours are lithium crimson, sodium yellow, potassium lilac, calcium orange-red and copper green. These five colours identify the metal ions present in a compound.
To carry out a flame test, clean a nichrome wire in concentrated HCl and heat it in a blue flame until no colour appears. Dip the clean wire into the sample, hold it in the hottest part of a blue Bunsen flame, and note the colour immediately.
Metals give different flame colours because, when heated, their electrons absorb energy and jump to higher energy levels, then release energy as light when they fall back down. Different metals have different energy gaps, so they emit light of different wavelengths, and wavelength determines colour.
Flame tests do not work well for mixtures because some colours are much brighter than others and mask them. For example, a sample containing sodium and potassium shows bright yellow from sodium, so the pale lilac of potassium is missed.
Lithium gives a crimson (deep red) flame, while calcium gives an orange-red (brick red) flame, so lithium is the deeper red. Confusing these two colours is a common exam trap.
Nichrome wire is used in flame tests because it contains metals that don't produce visible flame colours, so it won't interfere with the result. Steel wire would interfere, and wire gives more consistent results than wooden splints.
The wire is dipped in concentrated HCl and heated in a blue flame until no colour appears, to remove metal ions from previous tests. Contamination from previous tests would give false colours.
Sodium produces such a bright, intense yellow flame that it overwhelms almost every other colour. If a sample has both sodium and potassium, the yellow hides the pale lilac of potassium, and even tiny amounts of sodium contamination can mask other metals.
A flame test uses the hottest part of the blue Bunsen flame, at around 1500°C, because that heat is needed to excite the electrons. The colour is noted immediately, as it may only last a few seconds.
Flame tests can't identify metals in mixtures, because bright colours like sodium yellow mask paler ones. Some metals also produce similar colours that are hard to tell apart, the test is qualitative only, and it only works for metals that give visible light when heated.
A flame test identifies the metal ion, not the whole compound. For example, a yellow flame shows sodium ions are present, but it does not show which compound the sodium ions are in.