Instrumental analysis and flame tests: red for lithium
Lesson details
Learning outcome
I can identify metal ions based on the colour of their flame tests and understand how instrumental analysis methods are used for detecting and identifying elements.
Key learning points
- Positive ions burn with distinct colours that are visible when heated above a blue Bunsen flame.
- Instrumental methods are accurate, sensitive, and rapid for detecting and identifying elements and compounds.
- Unique flame emission spectra are produced for each positive metal ion.
- A spectrometer can split light from coloured flames into flame emission spectra.
- A spectrometer can measure more than one metal ion in a single solution and the concentration of each.
Keywords
Flame test - A test where a chemical put into a flame produces a characteristic colour (tests for metal ions).
Spectroscope - An instrument that separates light into its component wavelengths.
Ion - An ion is an atom or group of atoms with a positive or negative charge due to the loss or gain of electrons.
Concentration - The amount of a solute dissolved in a certain volume of solvent.
Calibration curve - A graph used to determine the concentration of a substance in a sample.
Common misconception
Flame colours are unique, even in mixtures.
Explain that strong colours, like sodium's yellow, can mask others. Use spectrometry to identify masked elements.
Teacher tip
Ensure safety precautions are followed; use clean equipment to avoid contamination during flame tests.
Equipment
Bunsen burner setup, 'unknown' metal salt samples to do flame tests, nichrome wire loops, dilute hydrochloric acid, beakers, matches.
Content guidance
Risk assessment required - chemicals
Risk assessment required - equipment
Supervision
Adult supervision required
Licence
except where otherwise stated. See Oak's terms & conditions (Collection 2).Lesson video
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Prior knowledge starter quiz
6 Questions
Q1.Which of the following particles are not found in the nucleus of an atom?
Q2.What charge does an ion have if it has gained electrons?
Q3.Which part of the atom is involved in chemical bonding?
Q4.Which of the following is a general property of metals?
Q5.Where are metals generally located on the periodic table?
Q6.What is an ion?
Assessment exit quiz
6 Questions
Q1.What is the purpose of a flame test?
Q2.Why is it important to clean the wire loop before conducting a flame test?
Q3.What flame colour does potassium produce?
Q4.What happens to electrons in metal ions when they absorb energy from the flame?
Q5.Why do different metal ions produce different flame colours?
Q6.What is emitted when electrons in metal ions return to their ground state after excitation?
To help you plan your 11 chemistry lesson on: Instrumental analysis and flame tests: red for lithium, download all teaching resources for free and adapt to suit your pupils' needs...
To help you plan your 11 chemistry lesson on: Instrumental analysis and flame tests: red for lithium, download all teaching resources for free and adapt to suit your pupils' needs.
The starter quiz will activate and check your pupils' prior knowledge, with versions available both with and without answers in PDF format.
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The assessment exit quiz will test your pupils' understanding of the key learning points.
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