Why water is the universal solvent, despite not being good at dissolving many substances

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

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

A chemical overview of water, whose uncommon properties help sustain life on Earth

The uneven distribution of charge in water molecules allows them to bond to each other and to surfaces, enabling them to move against gravity, including up plants through roots and stems. These bonds also keep water in a liquid state over a wider temperature range and make it less dense as it freezes. This causes ice to float and form an insulating layer for underwater ecosystems, from which all life originated.

Distinguishing polar and nonpolar molecules and why charges get distributed unevenly in molecules

Because each element has a unique number of protons and configuration where electrons exist, they attract electrons that are shared with other elements in chemical bonds to varying degrees. When this attraction—electronegativity—varies between two bonded elements, electrons are more likely to be near the more electronegative element and away from the less electronegative element. This can create regions of opposite charge, or poles, and thus polar molecules.

Learn why magnets, like statically charged balloons, can deflect water

While the oxygen atom in water molecules strongly attracts hydrogen's electrons—producing an uneven charge distribution that pulls water toward balloons that have been rubbed against surfaces—the presence of a magnetic field alters the path of these electrons, which produce their own tiny magnetic fields. The interaction of these fields repels water away from magnets, making it diamagnetic.

Debating whether water is or is not wet depends on one's definition of wetness

If defined as a liquid sticking to a surface, then water itself is not wet. The sensation of "wetness" arises from water molecules latching onto an object. This occurs because water is a polar molecule possessing local regions of positive and negative charge that are attracted to charge imbalances on the surface of materials.

Metals can be welded together in space without needing heat

On Earth, oxygen naturally reacts with metals to form an oxide layer on their surface, which prevents two different pieces from fusing when they come into contact. If the layer is worn away without oxygen to replenish it, metals can instead stick together upon impact—a phenomenon known as cold welding.

Plasma is the most abundant form of visible matter in the universe

When electrons are stripped from neutral atoms as a result of high-energy interactions, such as lightning strikes, the atoms become positively charged ions. The mix of these ions and negatively charged electrons, which are too energetic to recombine, is extremely electrically conductive and affected by magnetic fields.

Why trying to freeze helium creates a fluid that can travel through solids and climb walls

Once cooled to temperatures just above 2 Kelvin, helium-4 atoms begin to exhibit superfluidity, a quantum property in which all atoms collectively inhabit the same low-energy state and behave in perfect unison. This coordination removes the internal friction that causes liquids to cling to surfaces, allowing them to slide through microscopic pores and scale container walls.

A look at anoxygenic photosynthetic bacteria, which do not produce oxygen

Rather than using water to produce organic compounds and release oxygen, purple and green sulfur bacteria take up hydrogen sulfide, carbon dioxide, and light to produce water, elemental sulfur, and a carbohydrate. Other organisms can take up various molecules and elements, such as iron, which can replenish the electrons in pigments involved in light-dependent reactions.

How to create salad dressings with oil and water solutions that don't separate into layers

Such dressings, even when whisked together, often break within a few minutes, resulting in bites that are either harsh or oily. Small amounts of emulsifiers, such as mustard or mayonnaise, can stabilize and suspend oil droplets in water for longer periods because they possess both hydrophilic (water-loving) and hydrophobic (water-repelling) ends.

Odor blockers use nonpolar oils to trap smelly polar molecules

In the case of feces, gut bacteria produce compounds such as skatole and hydrogen sulfide, which the brain registers as unpleasant. Because oils do not dissolve in water, they can be used to create a layer on the surface that prevents smelly compounds underwater from escaping into the air.

Oxygen and ozone molecules absorb up to 99.9% of UV radiation reaching Earth

Although they make up no more than 10 out of every million molecules in the ozone layer, ozone provides outsized protection by absorbing the most energetic wavelengths of ultraviolet radiation. This absorption increases thermal energy in the stratosphere, causing temperatures there to rise with altitude.

Hydrogen vehicle adoption has struggled due to high costs and stiff EV competition

Despite features like fast refueling and zero emissions, hydrogen vehicles face significant hurdles in affordability and infrastructure. As of 2025, there are about 200,000 electric vehicle charging stations compared to fewer than 100 hydrogen fuel ones.

Humans need higher levels of water-soluble vitamins that easily pass through the body

There are two types of vitamins: lipid soluble and water-soluble. Water-soluble vitamins like B vitamins and vitamin C are in the watery parts of fruits and easily pass through the human body before being taken up by the bloodstream or exiting your body. But lipid (fat) soluble vitamins must be absorbed through the intestinal wall, carried by proteins, and then may be stored in the liver and other body parts—meaning there is greater risk of overdosing.

Glow sticks feed energy released in chemical reactions to fluorescent dyes

When bent, the glass tube inside the stick breaks, releasing hydrogen peroxide into the surrounding solution. The ensuing reaction creates unstable molecules that decompose and release energy, which is then absorbed by molecular dyes that emit light when their excited electrons return to lower energy states.

Tiny water droplets can blur a rainbow's colors into a foggy white

When sunlight enters water droplets, it can reflect from the inside and spread out into different colors, producing a series of colorful arcs—supernumerary bows—which we refer to as rainbows. For droplets a few hundredths of a millimeter in size, these arcs overlap onto each other, producing fogbows of white light.

Understanding why suction cups rely on Earth's atmosphere to work

When pressed against a surface, air is squeezed out of a sealed volume, causing the internal pressure to drop below the surrounding atmospheric pressure, and this imbalance creates the "sticking." For this reason, astronauts do not use suction cups or related technologies to stay on spacecraft during spacewalks.

Gold's electrical conductivity, reflectivity, and catalytic capabilities make it scientifically valuable

Although gold has been prized since its use in 40,000 BCE for decorative purposes, it has more recently served as a replacement for mercury in the production of PVC plastic. Because gold does not react with air or corrode, it has remained in circulation and reused in electronics and biomaterials.

Why helium mixtures are used in respiratory medicine

Unlike the air near Earth's surface, which is primarily composed of oxygen and nitrogen, heliox is composed entirely of oxygen and helium. Because helium is lighter than nitrogen, the lungs do not have to work as hard to push air, easing the uptake of oxygen via a ventilator, mask, or nasal tube.

'Dilution' is any use of a trademark that weakens its distinctiveness

Unlike trademark infringement that hinges on the likelihood of confusing customers, trademark dilution is an illegal practice that threatens the distinctiveness of a trademark. In the US, famous brands like Nike and Google have a right to protection from dilution.

The composition of comets earned them the nickname 'dirty snowballs'

The icy relics of the solar system are composed of rock, gravel, dust, and frozen molecules, such as carbon dioxide, carbon monoxide, methane, ammonia, and water. Once close to the sun, these compounds sublimate into gases, creating a fuzzy cloud that earned the comets another nickname in history: hairy stars.

Water vapor is used to manage heat in high-end smartphones

While smartphones have traditionally been cooled using a highly conductive plate that dissipates heat from the chip, vapor chambers offer a higher heat-removal capacity. This technology has been utilized in laptops for decades to absorb heat by cycling a fluid between liquid and gaseous phases.

Cats evolved from arid land animals, contributing to their aversion to water

Although positive water experiences can make some cats water-loving, they usually self-clean, making baths unnecessary.

'1440 Explores,' Episode 2: Why We Drink and What It Does to US

Alcohol is the world's most popular drug—a molecule that can calm or excite and bond communities or tear them apart. We trace alcohol's journey from ancient rituals to modern hangovers, uncover how it shaped civilizations, and dive into the neuroscience of how it affects your brain and body. With insights from leading experts, we ask: Given all that we know, why do humans continue to drink?

The boiling temperature of water decreases with increasing elevation because the molecules need less energy to overcome the lower atmospheric pressure associated with thinner air.

Conditioners can help unshrink garments by lubricating fibers

Textile fibers relax and shrink due to heat and moisture, disrupting hydrogen bonds. While loosely knitted fabrics are more prone to shrinkage than tightly woven ones, synthetic fibres like polyester resist shrinkage due to their crystalline structure.

All rainbows are 'raincircles' caused by water droplets separating white sunlight into a spectrum of colors, but Earth's surface blocks the bottom half of the circle from our line of sight.

The US dollar is the most widely circulated currency in the world, and is involved in nearly 90% of global transactions

While the sun's gravity keeps the planets in orbit, their gravity also pulls on the sun, causing it and everything else in the solar system to orbit around a mutual balance point called the barycenter—the true center of the solar system.

Most of the observable universe's volume consists of voids and supervoids—enormous regions of space with little to no galaxies, stars, or light.

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.

An investigation suggests a Scottish island became awash in forever chemicals via seafoam and seaspray—raising questions about what that means for the safety of other coastal areas.

Fireworks make a loud booming sound after exploding due to air expanding faster than the speed of sound.

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.

To reduce wrinkles in clothing, research recommends gentle wash cycles with more water and tumble drying with smaller loads and longer times.

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 price of gas is a composite made up of several different factors, with the federal gas tax making up less than 20% of what drivers pay at the pump.

Tattoos remain visible on your skin thanks to immune cells called macrophages

The original copy of the Declaration of Independence is not a pristine document, and even features a smudged anonymous handprint in the bottom left corner.

SpongeBob exemplifies Aristotle's philosophy for living well because he understands that happiness doesn't come from external factors like money, recognition, or power.

Memecoins are a type of cryptocurrency—a form of digital currency with a wide variety of uses—created around popular 'memes,' or viral internet jokes.

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

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.

Browse a detailed visual analysis of over 200,000 similes—comparisons that often use 'like' or 'as'—from popular fiction to see how frequently writers the same idiomatic expressions.

Gerrymandering works through two techniques: cracking opposing voters across districts to dilute their power, and packing them into a few to waste their votes in lopsided majorities.

Frank Lloyd Wright's houses are historically hard to sell because they're old, subject to local landmark commissions, and often unfashionable

Ebola is a filovirus, meaning it resembles a thread under a microscope, though it sometimes twists and can resemble a bowl of spaghetti.

The Beatles' US label rejected the band's first two singles, 'Please Please Me' and 'From Me to You,' with one executive calling the band 'dead in the water.'

A small portion of The Winstons' 'Amen, Brother,' an obscure '60s gospel record, is the basis for thousands of hip-hop tracks, making it one of the most sampled records ever that's informally known as 'the Amen break.'