Níkel

Níkel, with the chemical symbol Ni and atomic number 28, is a silvery-white lustrous metal that belongs to the transition metals group. It is known for its resistance to corrosion and its ability to be polished to a high degree of reflectivity. Níkel is found in Earth's crust only in chemically combined form, usually in ultramafic rocks, and in the interiors of larger nickel-iron meteorites. It is one of four elements (the others being iron, cobalt, and gadolinium) that are ferromagnetic at room temperature.

Níkel has a wide range of applications due to its unique properties. It is used in the production of stainless steel and other alloys, which are resistant to corrosion and oxidation. It is also used in rechargeable batteries, such as nickel-cadmium and nickel-metal hydride batteries, and in coinage. Níkel is also used in the production of catalysts, including those used in the hydrogenation of oils and fats.

Níkel is an essential element for living organisms, although it is toxic in large amounts. It is a component of many enzymes and is involved in the metabolism of carbohydrates and fats. In humans, níkel is absorbed through the digestive system and is excreted in the urine and feces. It is also found in the environment, primarily in the form of nickel compounds, which can be released into the air and water from industrial processes.

Níkel is not considered to be a rare element, but its extraction and processing can be environmentally damaging. The mining and processing of níkel ores can lead to soil and water contamination, and the disposal of níkel-containing waste can also have negative environmental impacts. As a result, there is ongoing research into more sustainable and environmentally friendly methods of níkel extraction and processing.