Colourful Campfires

Everyone knows that you get yellow fire from burning wood, depending on what you add to a fire you can change the colour of its flame. The reason particular colours are given out is due to the energy level the ‘burning’ happens at. Remember the old period table? (or if you had modern enough science teacher; a periodic galaxy?) well its all down its arrangement.

The Sciencey Bit

(Skip this if you really don’t want to know why) The reason different compounds or elements produce different colours when burnt is the oxygen combines with them changing the arrangement of the atoms electrons.

Electrons form orbits or ’shells’ with higher levels of potential energy for each one in each each orbit, filling up the bottom orbits first. When an electron is exchanged from one shell to another light (photons) must be emitted with an energy matching the change in ‘height’ (potential energy) to maintain balance. The energy of a photon is determined by the Planck constant multiplied by its frequency (E = h×ν) which means that different energies result in different frequencies some of which can be seen as a colour.

The Example Bit

The most readily known examples of coloured fire are interstellar stars, although in all honesty they’re not really balls of fire but energy releasing spheres of luminous plasma. Anyway, they come in a variety of different colours depending on there temperature which is based on there dominant fuel, in the The Sun’s case it is 75% Hydrogen and 24% Helium giving it a yellow colour from our atmosphere. As the Sun ages the Hydrogen will become Helium through fusion and it will appear red, just like the the Sun Krypton orbits in Superman and it is called what is known as a Red Dwarf. As the Helium ‘burns’ together into even denser materials it will eventually change to White Dwarf.

Another example that is slightly more down to Earth is the use of different compounds for stunning sky bound effects called fireworks. To produce the most brilliant colours other elements are used to enhance the colour produced from burning, usually Chlorine, which is toxic in large amounts.

The Safety Bit

WARNING: I wouldn’t suggest acquiring any of these elements and trying it out for yourself, especially since some of these substances alone are radioactive, toxic or both! This is intended as a reverse lookup; you see the colour then work out what made it. I’ve not listed every substance just the ones I could find any information on.

The Referencey Bit

Name	Metal	Image	Flame	Notes
Lithium Li   3	Alkaili			White Fume
Strontium Sr   38	Alkaline Earth			Violent Reaction in Moisture, White Fume
Calcium Ca   20	Alkaline Earth
Iron Fe   26	Transition		Gold	Easily Magnetic, Symbol from the Word ‘Ferrum’
Sodium Na   11	Alkali	Silvery White		Easily Cut with Knife, Reactive with Water, White Fume
Manganese Mn   25	Transition	Silvery Metallic	Yellowish green	Poisonous, esp. if inhaled
Molybdenum Mo   42	Transition	Grey Metallic	Yellowish green	May have facilitated multicellular lifeforms
Barium Ba   56	Alkali Earth			Mades rare Gem Benitoite
Boron B   5	Metalloids	(Deep) Brown	Bright green	Used in Scientific Glassware
Thallium Tl   81	Poor	Silvery White	Pure green	Highly Toxic
Antimony Sb   51	Metalloids
Tellurium Te   52	Metalloids	Lustrous Silver	Pale Green
Phosphorus P   15	Non	Dull Red with White Sheen	Pale bluish green	Reactive when Cut, therefore used in Matches
Zinc Zn   30	Transition			White Fume
Arsenic As   33	Metalloids		Blue	Extremely poisonous
Bismuth Bi   83	Poor		Blue	Slightly Radioactive, Very Low Toxicity, Yellow Fume
Caesium Cs   55	Alkaili		Blue	Slightly Radioactive
Copper Cu   29	Transition			Black Fume
Indium In   49	Poor	Light Grey	Blue	Used in Liquid Crystal Displays, Toxic
Lead Pb   82	Post-transition		Blue	High Density, Toxic, Stops Xrays Easily
Selenium Se   34	Non	Dark Grey with metallic sheen	Azure blue	Key Ingredient in Head’n'Shoulders, MacGuffin in Evolution
Potassium K   19	Alkali Metal	Silvery White		Highly Reactive with Water
Rubidium Rb   37	Alkali	Grey White		Highly Reactive with Water OR air
Aluminium Al   13	Poor		White	Common Use, Very High Strength:Weight Ratio
Magnesium Mg   12	Alkaline Earth			White Fume
Titanium Ti   22	Transition		White	Food Colourant E171 (Titanium Dioxide)

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