Sea water is a compound mixture of water, salts and minerals, and it contains trace amounts of atmospheric gases. Sea water is abundant and covers about 70 percent of the Earth's surface.
Sea water is a useful source of elements that are in high demand for commercial purposes. Most of the world's magnesium and bromide is extracted from seawater. In some parts of the world, people still evaporate seawater to obtain sodium chloride. Potassium, magnesium, sulfate, chloride, calcium and sodium are common in sea water. By density, these ions make up about 99 percent of the sea salts. Atmospheric gases such as nitrogen, argon, oxygen and carbon dioxide can also be found in sea water.