Sodium
Eleven is the theme for the day, so it’s no surprise that Sodium —atomic number 11 — is everywhere, too. Sodium compounds are among the most frequently used materials for industrial and domestic use, and salt is needed for human life.
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Sodium is the seventh most abundant element in rocks and the fifth most abundant metal. It reacts with water and oxygen in the air, and in liquid ammonia it forms a blue solution described as solvated electrons. However, the sodium ion itself is quite inert, with high solubility for its salts and weak complexation abilities.
Sodium compounds are among the most frequently used materials for industrial and domestic use, and salt is needed for human life. For that reason, it has been of strategic importance in hot, humid tropical regions.
Because of the inertness of the sodium ion, regular chemical reactions with sodium ions are limited, but sodium ions are essential to life for many reasons. The extracellular concentration of sodium ions in the human body and in animals is about 10 times higher than what is found inside the cells. This is not expected when passive diffusion through the cell membranes is considered. To keep that high gradient across a membrane requires energy, that is, an active transport using ATP. This is a means of energy storage for sudden use and for forming electrical potential gradients in nerve cells. A similar mechanism does not occur in plants, and this is one of the most important differentiating characteristics between animals and plants.
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Excerpted with permission, Chemical & Engineering News
Copyright © 2003 American Chemical Society