Element 56 in our International Year of the Periodic Table series is barium. Barium is found in green fireworks, used in X-ray imaging, and also in drilling fluids.

When you’re watching a fireworks display, barium compounds (commonly barium nitrate) are responsible for the green colours you see. Small particles of barium compounds can be dispersed after fireworks displays, which is a concern due to barium’s toxicity. For this reason, there is research focused on producing ‘greener’ green fireworks which could do away with the use of barium compounds.

Despite the toxicity of its compounds, barium sulfate is a compound given to patients as a ‘barium meal’ to allow X-ray imaging of the digestive system. This is possible because of the low solubility of barium sulfate – this stops the patient absorbing harmful amounts of barium as it passes through their body.

Barium sulfate is also used in a range of other applications. These include drilling fluids, white pigments in paints, and as a paper whitener.

Remember, you can keep track of all of the previous entries in this series on the site here, or on the Royal Society of Chemistry’s dedicated page.