Unusually stable, undiscovered elements may exist near atomic number 126

Build atomic nuclei to explore their instability and resulting radioactive decay

In this simulation, users can add protons and neutrons to create an atomic nucleus, view its half-life and decay options, and identify patterns in how specific combinations of particles create extremely stable nuclei, from which the nuclear shell model of stability emerged.

View the periodic table of radioactive elements, and a list of each's most stable isotopes

Technetium is the lightest artificial radioactive element, which is produced primarily as a byproduct of nuclear fission. Several unstable isotopes are commercially available to medical professionals and scientists, despite their radioactivity risks.

How the nuclear shell model explains the stability or radioactivity of atomic nuclei

When the number of protons and neutrons completely fills shells within the nucleus, the binding energy that prevents these particles from being pulled apart increases. These are called "magic numbers," and they produce atoms with exceptionally stable nuclear configurations.

Astatine-211 is a radioisotope that can be used for therapeutic cancer treatment

With less than 30 grams in the Earth's crust at any given time, astatine is the rarest naturally occurring element. Its decay produces alpha particles that can damage diseased cells with the same impact as 10,000 electrons.

An overview of radioactivity, which can spontaneously change one element into another

Unstable atomic nuclei can transmute into a new element—an atom with a different number of protons—by emitting an alpha particle (two protons and two neutrons) or a beta particle (an electron). The electron can emerge from the nucleus when a neutron, which has no charge, suddenly transforms into a proton and an electron, thereby maintaining zero charge before and after the transformation, but altering the original element.

While atoms are normally made of protons, neutrons, and electrons, exotic ones have been built with antimatter—alternate versions of normal matter that live for fractions of a second and are about a billion times as rare.

While atoms are normally made of protons, neutrons, and electrons, exotic ones have been built with antimatter—alternate versions of normal matter that live for fractions of a second and are about a billion times as rare.

The discovery of the neutron paved the way for nuclear weapons

In 1932, James Chadwick discovered the subatomic particle when trying to explain the radiation emitted by beryllium after it was bombarded with alpha particles. The radiation’s ability to eject protons from a target suggested a chargeless particle with slightly more mass than a proton.

View the most expensive materials on Earth, led by those forged in particle accelerators

Californium-252—valued at $27.8M per gram, as of 2025—is far rarer and more valuable than gold, silver, or diamonds due to production and transportation costs. The most expensive substance ever found or created is antimatter, costing approximately $62.5T per gram.

An explanation of isotopes, which can help scientists trace food, water, and farming choices

Atoms of the same element have the same number of protons, but experiments showed that atoms of the same element can move through electromagnetic fields as if they had different masses. These differences in mass come from variations in the number of neutrons, which contribute to the stability of atoms by providing a buffer to the repulsion between protons.

Learn about the history of quarks, found deep in the heart of every atom

Independently theorized by American physicists Murray Gell-Mann and George Zweig in 1964, experiments later showed that these particles come in six varieties, named up, down, top, bottom, charm, and strange. Combinations of these quarks, which are held together by mediators of the strong nuclear force—gluons—make up dozens of composite particles, including protons and neutrons in atoms.

View the evolution of atomic models, with four successively overturned between 1900 and 1926

Originally thought to be indivisible spheres unique to each element, the discovery of the electron by J.J. Thomson revealed them to be made of smaller particles. Ernest Rutherford's gold foil experiment uncovered the existence of nuclei, which Niels Bohr suggested were surrounded by electrons in fixed orbits. By applying quantum mechanics, Erwin Schrödinger replaced orbits with probability clouds.

How gold, platinum, and many rare earth elements form during neutron star mergers

While massive stars naturally fuse elements as heavy as iron, an analysis of gravitational waves from the collision of two neutron stars revealed that more massive elements are created in this environment via rapid neutron capture—the r-process. This phenomenon sees existing iron nuclei absorb plentiful free neutrons, many of which decay into protons, creating new elements.

By organizing elements by atomic weight, Dmitri Mendeleev created the periodic table

The organization included groupings based on similar chemical properties and patterns in atomic weights. This left gaps that were used to predict the properties of elements yet to be discovered—including germanium and gallium—with high accuracy.

Radioactive elements can generate electricity, sterilize products, and date artifacts

Since their discovery in the 1890s, these substances have been incorporated throughout our daily lives, from treating food packaging and improving microbial safety to their presence in smoke detectors and gauges for ice cream aeration.

An overview of helium, the nonrenewable resource that's lighter than air

The second element in the periodic table naturally forms deep underground over the course of billions of years through the decay of radioactive elements, but it is used and lost to space at rates faster than it is generated. Because of this and its extensive applications in scientific technologies, scientists continue to seek avenues for its exploration, storage, and recycling.

Uranium's ability to split easily makes it the most common catalyst for nuclear power

Uranium is commonly found in rocks, water, and soil worldwide, but significant industrial processes are needed to process and enrich it for efficient reactor usage. After being irradiated in reactors, it must be cooled down before disposal.

Gravity, electromagnetism, and two nuclear forces make up nature’s fundamental forces

While gravity is the most familiar force, it is also the weakest and the only one without a particle to mediate the force. The weak nuclear force is responsible for radioactive decay and transmutation of elements, while the strong nuclear force holds quarks together.

Radioactive elements can introduce software errors because the ionizing radiation they produce can detach electrons from atoms, and computer code relies on the distribution of electrons.

An overview of atomic composition, scale, and structure, which is almost all 'empty' space

It takes about 500,000 carbon atoms lined up next to one another to span the thickness of human hair, and over 99.9994% of the mass of each is contained in the nucleus. About 99.999999999999% of an atom's volume lies outside this nucleus, where electrons exist in clouds of probability. Removing these clouds, the Empire State Building would be the size of a rice grain.

The story of the Manhattan Project's unused demon core

A 3-inch, 14-pound sphere of nuclear reactive plutonium-gallium was set to be delivered to the Pacific Theater in 1945 to become the third atomic bomb dropped over Japan. When Japan surrendered, it was returned to Los Alamos in New Mexico for experiment, where two scientists would die testing whether the core could reach criticality—where it would release intense energy—via the use of a dense reflector. Watch the story here.

Neutron stars, the remains of some massive stars after they explode in a supernova, are the densest directly observable objects in the universe.

86% of the world's 12,321 nuclear warheads are held by just two countries

As of early 2026, the US and Russia together control about 86% of the world's more than 12,000 nuclear warheads—over 9,600 in military stockpiles. None of the seven other nuclear nations holds more than 600.

As of 2026, the majority of US states have unsafe radon exposure levels

Alaska, South Dakota, Pennsylvania, Ohio, and Washington top the list of states with exposure levels above 4 picocuries per liter for this naturally occurring radioactive gas. While these state-level averages vary from one county, municipality, and home to another, the EPA encourages those in the highest-risk states to test their homes.

What are rare earth elements?

Rare earth metals are 17 elements in the periodic table critical for modern technologies like electronics and defense systems. Although the US once led in their production, it now faces significant challenges in competing with China’s lower costs and control of over 70% of the global output.

Create anything from the elements in Little Alchemy 2

Various ancient cultures believed the most abundant substances in the world were its basic elements: earth, water, air, and fire. We may know better now, but you can make almost anything from those four things. Little Alchemy 2 is a fun, cartoonish game that allows users to create more complex items from simple substances.

As of 2025, LUX-ZEPLIN is the world's most sensitive dark matter experiment

The experiment is designed to indirectly detect WIMPs—weakly interacting massive particles and a candidate for what dark matter is made of—by looking for light produced when they collide with xenon atoms. Such collisions would also release electrons, which are then manipulated to produce a secondary light signal that helps rule out background effects.

Lithium can store and deliver substantial energy for its cost and weight

When exploring which compounds would be best suited for batteries, scientists sought elements that were relatively inexpensive to mine, readily available, and that provided high energy density—how much chemical energy an element could store for its size. Lithium-ion batteries provide these benefits and discharge at very low rates when unused.

How fusion—which releases energy when two lighter atoms combine to form a heavier atom—differs from fission

In 1984, Operation Smash Hit intentionally crashed a 239-ton train into a nuclear waste canister at 100 miles per hour to prove the canister's safety, which remained completely intact and lost just 0.29 of its 100 pounds of pressure.

Sunflowers have long been a symbol of nuclear disarmament because they can extract large amounts of radioactive cesium from soil.

At the beginning of the 20th century, a group of young men ate standard American food—replete with food additives like borax and formaldehyde—as part of government research to better understand food safety.

As of 2025, the most cited papers in science include a review of graphene, methods to improve image recognition, streamlining electron density calculations, and optimizing protein studies.

The United States is one of only around two dozen countries with a fully federal system of government, in which power is divided between national and state governments.

Dirty lightning is a thunderstorm created from friction between rising and falling flows of ash and smoke during volcanic eruptions.

Explore fun facts from the USPS, including unique post office buildings, a stamp that traveled past Pluto, and more.

Pure water does not conduct electricity because this flow of energy requires the movement of charged particles, and water is a neutral molecule.

In 2026, Finland was named the world's happiest country for the ninth consecutive year based on its wealth, social safety network, and high life expectancy, among other factors.

11 people died from firework injuries in the US in 2024.

Bone marrow (soft tissue found inside certain bones) generates roughly 500 billion new blood cells each day

Indefinite cloning of some endangered species may not sustain their longevity because cloning success rates decrease as genetic mutations accumulate.

Explore chaos in this simulation of two double pendulums, where small differences in the release angles produce wildly different outcomes.

Louisiana's 'Cancer Alley' is infamous for having some of the highest industrial pollution, toxic air emissions, and cancer risks in the US.

The Great Salt Lake's distinct dual coloration results from high-salinity organisms that only live in the northern portion and produce a purple protein.

In 1963, a basement renovation in Turkey revealed a passageway to a hidden, multilevel underground city that once housed as many as 20,000 people

Abraham Lincoln was almost assassinated weeks before his inauguration as he traveled from Illinois to DC through Baltimore in 1861; it took two independent claims for Lincoln to be convinced the threat was real

Lesser-known phobias include turophobia, or the fear of cheese, and nomophobia, the fear of being without your cell phone.

Sony set the standard for cylinder-shaped batteries when it repurposed manufacturing equipment used to make rolls of magnetic recording tape.

Use this tool to calculate the dollar value of your parental mental load, from meal planning to coordinating after-school care, then see resources that help generate solutions.

Clever Hans was a 1900s horse that was believed to be able to solve math equations, tell time, and read and comprehend German, until a psychology student discovered how he got his answers.