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.


Ytterbium, symbol Yb, soft, malleable, ductile metallic element that has a bright, silvery luster. Ytterbium is one of the rare earth elements in the lanthanide series of the periodic table. The atomic number of ytterbium is 70.

In 1878, the Swiss chemist Jean Charles de Marignac separated a new substance from the rare earth elements and named it ytterbium. In 1907 and 1908, however, the French chemist Georges Urbain and the Austrian chemist Carl Auer von Welsbach independently separated Marignac's ytterbium into two elements, which are now called ytterbium and lutetium.

Ytterbium is reasonably stable but reacts slowly with water to liberate hydrogen. Ytterbium occurs in combination with such minerals as xenotime, euxenite, monazite, and gadolinite. It ranks about 44th in natural abundance among the elements in the earth's crust. Ytterbium has potential applications in alloys, electronics, and magnetic materials.

Ytterbium melts at 819° C (about 1506° F), boils at about 1196° C (about 2185° F), and has a specific gravity of 7. The atomic weight of ytterbium is 173.04.