What are the flame colors of alkali metals?

The flame colours of alkali metals are lilac for potassium, crimson for lithium, and yellow for sodium.

Alkali metals are a group of chemical elements from the s-block of the periodic table. They include lithium (Li), sodium (Na), potassium (K), rubidium (Rb), caesium (Cs), and francium (Fr). When these metals are heated, they produce characteristic flame colours. This is due to the excitation of electrons in the metal ions, which then emit energy as light when they return to their ground state.

Lithium ions produce a crimson or red flame when heated. This is because the energy emitted by the excited electrons falls within the red part of the visible light spectrum. Sodium ions, on the other hand, produce a bright yellow flame. This is because the energy emitted by sodium ions falls within the yellow part of the spectrum. Potassium ions produce a lilac or purple flame, as the energy they emit falls within the violet part of the spectrum.

These flame tests are often used in labs to identify unknown substances. By observing the colour of the flame, chemists can determine which alkali metal is present in a sample. However, it's important to note that other factors can also affect the colour of the flame, such as the presence of other substances. Therefore, flame tests should be used in conjunction with other tests to confirm the identity of a substance.

Remember, alkali metals are highly reactive, especially with water and air. Therefore, always handle them with care and under the supervision of a trained professional.