In its solid form, sodium is a white, silvery metal that can be cut with the edge of a coin. If cut, the surface of the metal exposed to the air turns an opaque gray color due to the rapid formation of an oxide coating. A similar process happens with denser metals and the formation of rust. When in salt form, sodium appears white or gray. Sodium in its metal form may cause irritation if it touches your skin. Severe exposure to sodium can cause sneezing, coughing, difficult breathing and chemical bronchitis. If it comes into contact with your eyes, it may cause permanent damage or vision loss.
Sodium is highly reactive around water, producing sodium hydroxide and hydrogen gas. The heat generated when sodium meets water can ignite the hydrogen gas, causing explosions. Sodium does not react with nitrogen and hardly reacts with carbon. Sodium does not react with halogens. When sodium comes into contact with alcohols, it produces similar results as the sodium-water combination, only slower. Most sodium reactions initiated in commercial industry are to produce organic compounds, such as fragrances. When sodium reacts with oxygen, a yellow light is given off.
Sodium is one of the most important alkaline, or earth salt, metals found in nature. Its presence in the diet helps the body maintain a healthy water balance between the body's cells and fluids. Too much dietary sodium can lead to high blood pressure as well as kidney damage. Sodium ions also help the transmission of electrical signals in your nervous system. Other salts found in nature are sodium carbonate, sodium borate, sodium nitrate and sodium sulfate. These salts are all found in seawater, salty lakes and mineral spring water.
Sodium is used in a variety of settings, from street lighting to soap production. Sodium vapor lamps are often used in street light installations. Sodium is also added to alloy metals to help improve their structure. Adding fatty acids to soap adds sodium, as sodium salts are a part of a fatty acid structure. Sodium carbonate is also used to make glass. Liquid sodium is used in the nuclear energy industry to transfer heat away from the reactors, cooling them.