Reference Terms
from Wikipedia, the free encyclopedia
Chemical compound
A chemical compound is a chemical substance consisting of two or more different chemically bonded chemical elements, with a fixed ratio determining the composition. The ratio of each element is usually expressed by chemical formula. For example, water (H2O) is a compound consisting of two hydrogen atoms bonded to an oxygen atom.
The atoms within a compound can be held together by a variety of interactions, ranging from covalent bonds to electrostatic forces in ionic bonds. A continuum of bond polarities exist between the purely covalent bond (as in H2) and ionic bonds. For example H2O is held together by polar covalent bonds. Sodium chloride is an example of an ionic compound.
Related Stories
1
2
Matter & Energy News
July 3, 2026
July 3, 2026 Researchers have created quantum control techniques that can make a system appear to run backward in time. By precisely managing quantum measurements, they can reshape the system's arrow of time and even harvest energy from the measurement process ...
July 2, 2026 A major breakthrough in quantum technology has turned magnons, tiny magnetic waves once considered too short-lived for practical use, into promising carriers of quantum information. Researchers extended their lifetime by nearly 100 times, reaching ...
July 1, 2026 A new quantum device can generate precisely controlled bursts of sound-like particles, or phonons, by forcing electrons through an ultra-thin crystal at extremely low temperatures. The surprising behavior pushes beyond the limits predicted by ...
July 1, 2026 A surprisingly simple fuel modification could help tackle one of diesel engines’ biggest problems: pollution. Researchers reviewing studies from around the world found that mixing small amounts of water into diesel fuel can dramatically reduce ...
June 26, 2026 A new sunlight-powered material can convert visible light into higher-energy UV light, overcoming a challenge that has frustrated scientists for years. The breakthrough could enable cleaner air purification, solar-driven chemistry, and advanced ...
June 24, 2026 A groundbreaking superconducting X-ray spectrometer has begun operation at BESSY II, giving Europe its first TES-based system and boosting photon detection efficiency by up to 1,000 times. The advance enables scientists to explore atomically thin ...
June 23, 2026 A newly proposed quantum sensing technique could make it much easier to identify one of physics’ newest and most intriguing classes of magnets: altermagnets. These unusual materials, discovered only a few years ago, appear to combine the speed and ...
June 23, 2026 NASA’s upgraded Cold Atom Lab is turning the International Space Station into a frontier for quantum research, creating ultra-cold matter that behaves in astonishing ways. The experiments could ...
June 21, 2026 Researchers found that a Chinese sodium-ion battery performs far better than expected, with production quality and design features comparable to Tesla’s batteries. If engineers can improve ...
June 20, 2026 Researchers found that twisting layered sheets of hexagonal boron nitride can dramatically change the light produced by quantum emitters embedded within the material. The technique offers an unexpected new level of control over components that could ...
June 20, 2026 The global cobalt supply chain is more interconnected—and more vulnerable—than previously thought, with disruptions capable of triggering far-reaching cascades across multiple countries and industries. Researchers warn that protecting battery ...
June 17, 2026 A clever nanoscale redesign may have solved one of superconductivity’s biggest problems. Researchers in Sweden discovered that by subtly sculpting the surface beneath an ultrathin superconducting material, they could make it stay superconducting ...
Latest Headlines
updated 12:56 pm ET
July 2, 2026 An unusual gravitational wave signal has renewed hopes that primordial black holes, long considered purely theoretical, may finally be within reach of discovery. If confirmed, they could solve one of ...
July 1, 2026 A decades-old puzzle about water has finally been unraveled. Researchers found that water trapped in tiny nanoscale spaces is not inherently more reactive. Instead, the intense pressures created ...
June 29, 2026 Researchers have shown that ultracold atoms can be driven into a strange new quantum state called a fractional Fermi sea, where particles organize themselves in unexpected ways. The discovery points ...
June 27, 2026 Scientists have uncovered a new explanation for what powers Yellowstone and other supervolcanoes. Instead of a deep plume rising from near Earth’s core, a broad “mantle wind” may push hot rock ...
June 27, 2026 Astronomers studying the rare supernova SN 2021yfj discovered material from one of the deepest layers of a dying star, providing a rare look at its hidden interior. The finding confirms key theories ...
June 19, 2026 Scientists have uncovered a surprising connection between quantum gravity and an exotic quantum state of matter that could explain why the universe isn’t expanding wildly fast. The study suggests ...
June 18, 2026 A new theory suggests the universe is constantly recording its own history in the fabric of spacetime. If correct, this cosmic memory could help solve some of the biggest puzzles in physics, from ...
June 16, 2026 Physicists have solved a long-standing problem involving systems that appear to violate Newton’s third law, such as bird flocks and bacterial ...
June 16, 2026 Researchers discovered that hydrogen radicals generated by intense UV light can break down stubborn PFAS “forever chemicals” without added chemicals. The breakthrough reveals a key mechanism that ...
June 15, 2026 Scientists have found that staple-shaped particles can tangle together to create a material that is both strong and flexible. Unlike conventional materials, these particles can be locked into a ...