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Barium has the electron configuration [Xe] 6s² and commonly forms Ba²⁺ ions. The soft, silvery-white metal oxidizes readily in air and reacts with water to produce hydrogen and strongly basic barium hydroxide. Its yellow-green flame emission provides a characteristic test. Barium’s large ionic radius influences the coordination and solubility of its salts: many are soluble, while compounds such as BaSO₄ are notably insoluble. These differences underpin uses ranging from sulfate analysis and radiopaque contrast media to industrial processes and fireworks. Safety depends on chemical form: soluble barium salts are highly toxic, whereas insoluble BaSO₄ is essentially non-toxic. The topic also considers barium’s environmental relevance and its role in gravimetric analysis.