The lightest known metal can also lighten your mood. Lithium, atomic number 3, is an element of many uses. It's used in aircraft manufacture and in certain batteries. It's also used in mental health: Lithium carbonate is a common treatment of bipolar disorder, helping to stabilize the wild mood swings caused by the illness.
Lithium has a flashy discovery story — literally. A Brazilian naturalist and statesman, Jozé Bonifácio de Andralda e Silva, discovered the mineral petalite (LiAISi4O10) on the Swedish isle Utö in the 1790s, according to the Royal Society of Chemistry (RSC). The mineral is white to gray, but when thrown into fire, it flares bright crimson.
In 1817, Swedish chemist Johan August Arfvedson discovered that petalite contained a previously unknown element. He wasn't able to isolate the metal entirely, but did isolate one of its salts. The name, lithium, is from "lithos," the Greek for "stone."
It took until 1855 for someone to isolate lithium: British chemist Augustus Matthiessen and German chemist Robert Bunsen ran a current through lithium chloride in order to separate the element.
Just the facts
According to the Jefferson National Linear Accelerator Laboratory, the properties of lithium are:
- Atomic number (number of protons in the nucleus): 3
- Atomic symbol (on the Periodic Table of Elements): Li
- Atomic weight (average mass of the atom): 6.941
- Density: 0.534 grams per cubic centimeter
- Phase at room temperature: Solid
- Melting point: 356.9 degrees Fahrenheit (180.5 degrees Celsius)
- Boiling point: 2448 degrees Fahrenheit (1342 degrees Celsius)
- Number of isotopes (atoms of the same element with a different number of neutrons): 10; 2 stable
- Most common isotopes: Li-7 (92.41 percent natural abundance), Li-6 (7.59 percent natural abundance)
The brain on lithium
Lithium is a special metal in many ways. It's light and soft — so soft that it can be cut with a kitchen knife and so low in density that it floats on water. It's also solid at a wide range of temperatures, with one of the lowest melting points of all metals and a high boiling point.
Like its fellow alkali metal, sodium, lithium reacts with water in showy form. The combo of Li and H2O forms lithium hydroxide and hydrogen, which typically bursts into red flame.
Lithium makes up a mere 0.0007 percent of the Earth's crust, according to the Jefferson Lab, and it's only found locked up in minerals and salts. Those salts have the power to change the brain: lithium salts were the first drugs approved by the Food and Drug Administration to treat mania and depression, according to the National Institute of Mental Health.
Today, lithium carbonate is the compound most often sold as a pharmaceutical. Oddly, no one knows exactly how lithium works to stabilize mood. Studies show multiple effects on the nervous system. In 2008, for example, researchers reported in the journal Cell that lithium interrupts the activity of a receptor for the neurotransmitter dopamine. It also appears to plump up brain volume, according to a 2011 study in the journal Biological Psychiatry (though this research is hotly contested).
- Lithium-ion batteries are the key to lightweight, rechargeable power for laptops, phones and other digital devices. According to the U.S. Geological Survey, Argentina and Chile increased their lithium production 15 percent each in 2014 alone to meet the growing demand. Worldwide, production jumped 6 percent that year.
- The United States has one lithium mine, in Nevada, according to the USGS. Chile and Australia produce the most lithium in the world.
- Naturally occurring lithium in drinking water correlates with lower levels of suicide, according to a 2009 study that highlights lithium's role in the brain. But psychiatrists are careful about prescribing lithium in high doses, particularly because it can pass through the placenta and have unknown effects on the developing fetus.
- Lithium was one of the three elements produced in large quantities in the Big Bang, according to physicists. The others were hydrogen and helium.
Lithium has a problem — or astrophysicists do. The amount of lithium that should have been produced in the Big Bang is about three times as high as actually seen in the oldest stars.
This discovery was first made in the 1980s, said Pasquale Serpico, a cosmologist at the National Center for Scientific Research (CNRS) and the University of Savoy Mont Blanc in France. It created a "tension," Serpico said, between what the Big Bang data and the star observations were telling researchers about lithium's abundance.
"The community started to look for possible loopholes or overlooked effects that might reconcile this tension," Serpico told Live Science.
It's a search that's still going on. There are two basic possibilities, Serpico said: One is that scientists are missing something about the primordial conditions of the universe that would explain the absent lithium. This is a tough explanation to find. Researchers at the Laboratory for Underground Nuclear Astrophysics (LUNA), an underground accelerator in Italy, recently experimented with recreating the conditions of the Big Bang and found that the amounts of helium and hydrogen created matched with observations seen in the universe, while lithium stubbornly stayed too high. Lithium remains an outlier in an otherwise functional explanation for how the universe formed.
Another possibility is that there is a "new physics" explanation for the missing lithium in the universe today, Serpico said. In other words, the lithium was created in the expected amounts at the Big Bang, but something mysterious and unknown has been destroying it more rapidly than expected ever since.
"We just found out that a loophole in standard physics in the way people approximated the description of a standard physical phenomenon might make a new physics explanation less challenging," Serpico said.
The researchers focused on a phenomenon common in the early days of the universe, when space was humming with energetic photons (light particles). Against these "hot" conditions, elementary particles, the building blocks of atoms, were born. Now, in a study published in March 2015 in the journal Physical Review Letters, Serpico and his colleagues have identified an overlooked sweet spot in this phenomenon. At a certain energy level, injecting new energetic photons into the mix efficiently destroys beryllium-7, the precursor to lithium-7, without affecting other nuclei. Those other nuclei remain at the same levels seen in the star observations. Suddenly, the potential for a Big Bang reaction with less lithium than previously expected starts to make sense.
"Now our problem is, is this just a curiosity, or can it be a viable mechanism?" Serpico said.
The question could be answered with probes such as NASA's PIXIE mission, which aims to map the energy spectrum of the cosmic microwave background of the universe, which is the heat left over from the Big Bang, with unprecedented precision. Depending on the specific model, there is also hope that particle colliders like the Large Hadron Collider or the proposed Search for Hidden Particles (SHiP) project at the European Laboratory for Particle Physics (CERN) could provide indirect hints, he said.