Sodium is a chemical element with the symbol Na and atomic number 11, classified as an alkali metal in the periodic table. It is a soft, silvery-white metal that is highly reactive, particularly with water and oxygen, leading to rapid oxidation in air and violent reactions that produce hydrogen gas and heat. In its elemental form, sodium is not found freely in nature due to its reactivity and is typically extracted from compounds like sodium chloride. In food and biological contexts, sodium ions (Na+) are essential electrolytes that play critical roles in maintaining fluid balance, nerve impulse transmission, and muscle function. Common dietary sources include table salt (sodium chloride), and while sodium is vital for human health, excessive intake is linked to health issues such as hypertension and cardiovascular diseases, as per studies in the Journal of the American College of Cardiology. Industrially, sodium is used in the production of compounds like sodium hydroxide and in nuclear reactors. Physically, it has a low melting point and is malleable, making it useful in alloys. Chemically, it readily forms ionic compounds due to its single valence electron. Despite its importance, handling elemental sodium requires caution due to its reactivity. Research from sources like the Royal Society of Chemistry highlights its role in both everyday applications and advanced materials science, emphasizing the need for controlled exposure in laboratory and industrial settings.