Calcium is a chemical element with the symbol Ca and atomic number 20. It belongs to the alkaline earth metals group in the periodic table. As you can see in this atomic model, calcium has 20 protons in its nucleus and 20 electrons arranged in four electron shells. This soft, gray metal is one of the most abundant elements in the Earth's crust and plays a crucial role in biological processes.
Calcium has several distinctive physical properties. It is a soft, gray metallic element that can be cut with a knife. The metal has a relatively low melting point of 842 degrees Celsius and a boiling point of 1484 degrees Celsius. With a density of only 1.55 grams per cubic centimeter, calcium is lighter than most metals. One of its most notable characteristics is its high reactivity - calcium reacts vigorously with water, producing hydrogen gas and heat, and it also reacts readily with oxygen in the air.
Calcium plays a crucial role in many biological processes. It is most famous for being essential in the formation and maintenance of bones and teeth, where 99% of the body's calcium is stored. Beyond structural support, calcium is vital for muscle contraction, allowing our muscles to move properly. It also enables nerve function by helping transmit electrical signals throughout the nervous system. Calcium is necessary for blood clotting, helping wounds heal by forming clots. Additionally, it participates in cell signaling and enzyme activation. Adults typically need 1000 to 1200 milligrams of calcium daily to maintain these essential functions.
Getting enough calcium is essential for maintaining good health. The best sources of calcium include dairy products like milk, cheese, and yogurt, which are rich in easily absorbed calcium. Leafy green vegetables such as kale and broccoli also provide significant amounts of calcium. Fish with edible bones, like sardines and canned salmon, are excellent sources as well. Many foods are also fortified with calcium, and supplements are available for those who cannot meet their needs through diet alone. Calcium deficiency can lead to serious health problems, including osteoporosis, which causes bones to become weak and brittle, muscle cramps and spasms, and various dental problems.
Calcium has numerous important industrial applications beyond its biological roles. In steel production, calcium is used to remove impurities and improve the quality of the final product. The construction industry relies heavily on calcium in cement and concrete manufacturing, where calcium compounds provide the binding properties that make concrete strong and durable. In the paper and pulp industry, calcium compounds are used in the bleaching and processing of paper products. The pharmaceutical industry uses calcium in various medications and as a supplement. Calcium also serves as a food additive and preservative in the food industry. Water treatment facilities use calcium compounds to adjust pH levels and remove impurities. Finally, calcium plays a role in metallurgy and alloy production, helping to create stronger and more durable metal products.