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Exciting Electrons

Exciting Electrons using LIGHT

When metals or metal salts are heated in a flame, the flame becomes highly coloured. These colours are due to the electrons getting excited!

Fireworks are made up of metal salts - they take advantage of the different colours that are produced when metal ions or atoms are heated.

Lithium (left), sodium (middle) and copper (right) salts give pink, yellow and green flame colours

Lithium (left), sodium (middle) and copper (right) salts give pink, yellow and green flame colours

What’s the Chemistry?

The heat of the flame causes electrons in the metal atom to rise up to higher energy levels. This "excited state" is not stable so the electron falls back to its original energy level ("ground state"). As it falls, it releases the energy as LIGHT.

Why do different metals cause different flame colours?

Different metal atoms have different separations between their ground and excited states ("energy gap"). This means that they emit different amounts of energy when electrons fall from the excited state to the ground state.

Exciting and de-exciting electrons gives colour

If you look at the spectrum of visible light below, you can see that different colours correspond to different energies (i.e. red light is at the 700 nm end of the spectrum and blue is at the 400 nm end).The Electromagnetic Spectrum

nm= nanometre (one thousandth of a millionth of a metre (10-9))

If a metal atom has a small energy gap, low energy visible light (e.g. red light) will be emitted as excited electrons fall back to their ground state.

If a metal atom has a large energy gap, high energy visible light (e.g. blue light) will be emitted as excited electrons fall back to their ground state.

The colour depends on how much energy is absorbed


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Back to the Topics List

What are electrons? - Where are Electrons? - Electrons in Molecules - How big are electrons? - Exciting Electrons using LIGHT - Exciting Electrons using ELECTRICITY - Exciting Electrons using CHEMICALS - Oxidation & Reduction - Oxidation Experiment - Sodium & Water - Reduction Experiment - Potassium Permanganate Volcano - Oxidation experiment - Ammonia - What is Electricity?

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