Matter & Energy

Matter is composed of atoms or groups of atoms called molecules. The arrangement of particles in a material depends on the physical state of the substance. In a solid, particles form a compact structure that resists flow. Particles in a liquid have more energy than those in a solid. They can flow past one another, but they remain close. Particles in a gas have the most energy. They move rapidly and are separated from one another by relatively large distances.


Rutherfordium, unstable chemical element with atomic number 104. In 1969 it was synthesized at the Lawrence Berkeley National Laboratory, Berkeley, California, by United States scientists who proposed the name rutherfordium, in honor of British physicist Ernest Rutherford. Russian scientists at the Joint Institute for Nuclear Research, Dubna, Russia, who claim to have synthesized the element in 1964, proposed the name kurchatovium, in honor of Russian atomic physicist I. V. Kurchatov. According to a convention adopted in 1980 for naming elements 104 and beyond, however, the element was named unnilquadium. In 1997 the International Union of Pure and Applied Chemistry (IUPAC) adopted the recommendation of the American Chemical Society to name the element rutherfordium. Modern atomic theory predicts that element 104 would be chemically similar to hafnium. At least 14 isotopes of rutherfordium have been synthesized.

See Atom; Chemical Elements; Periodic Law.