Li
Overview
Li is the chemical symbol for lithium, a chemical element with the atomic number 3. It is a soft, silvery-white alkali metal. Under standard conditions, it is the lightest metal and the lightest solid element. Like all alkali metals, lithium is highly reactive and flammable, and must be stored in mineral oil. When cut, it exhibits a metallic luster, but moist air corrodes it quickly to a dull silvery gray, then black tarnish. Due to its high reactivity, lithium never occurs freely in nature and instead, only appears in compounds, which are usually ionic.
Physical and Chemical Properties
Lithium is notable for its low density (0.534 g/cm³), which is about half that of water. It has a melting point of 180.5 °C (356.9 °F) and a boiling point of 1,342 °C (2,448 °F). Lithium has a high specific heat capacity, which makes it useful in heat transfer applications. It is also the least dense metal and the least dense solid element.
Chemically, lithium is highly reactive and flammable. It reacts vigorously with water to form lithium hydroxide and hydrogen gas. In air, it reacts with nitrogen to form lithium nitride. Lithium's reactivity is due to its low ionization energy and the small size of its atom, which allows it to easily lose its single valence electron to form a cation.
Occurrence and Production
Lithium is found in trace amounts in numerous minerals, but the primary sources are spodumene and petalite. The largest producers of lithium are Australia, Chile, and China. Lithium is extracted from mineral ores by roasting and leaching processes, or from brine pools by evaporation and precipitation.
Applications
Lithium has a wide range of applications due to its unique properties. It is used in the manufacture of lithium-ion batteries, which are widely used in portable electronic devices, electric vehicles, and grid energy storage. Lithium is also used in the production of high-temperature lubricants, glass and ceramics, and as a flux in welding and soldering.
In the field of medicine, lithium salts such as lithium carbonate are used as mood stabilizers in the treatment of bipolar disorder. Lithium compounds are also used in the production of synthetic rubber and in the air purification industry to absorb carbon dioxide.
Biological Role and Toxicity
Lithium is not considered an essential nutrient for humans, but it has been found to have some biological activity. Trace amounts of lithium are present in many foods and in drinking water. In medicine, lithium salts are used to treat psychiatric disorders, but they must be used under strict medical supervision due to their narrow therapeutic index and potential for toxicity.
Lithium toxicity, also known as lithium poisoning, can occur if lithium levels in the body become too high. Symptoms of lithium toxicity include nausea, vomiting, diarrhea, tremors, confusion, and in severe cases, seizures and coma. Long-term use of lithium can also lead to kidney damage and thyroid dysfunction.
Environmental Impact
The extraction and processing of lithium can have significant environmental impacts. Mining operations can lead to habitat destruction, water pollution, and the generation of large amounts of waste. The evaporation of brine pools for lithium extraction can also deplete local water resources, affecting ecosystems and communities.
Recycling of lithium-ion batteries is an important aspect of reducing the environmental impact of lithium use. Recycling processes can recover valuable materials and reduce the need for new mining operations. However, the recycling of lithium batteries is still a developing field, and improvements in technology and infrastructure are needed to make it more efficient and cost-effective.