An atom of radium gives off one alpha particle in decaying to radon . Alpha particles are used to bombard other nuclei in creating artificial radioactivity and are the least damaging to human tissue of all radioacitve emanations. Alum Alum is a type of double salt obtained by crystallizing mixtures in correct proportions. A liquid or solid alloy or mixture of mercury with another component, which is usually a metal. The component metal must be soluble in mercury .
Examples are lithium , sodium , potassium , and cesium .
Industrial applications of amalgams containing other componetns are in silvering mirrors, in special techniques in metallurgical analysis, and as catalysts . Silver and gold are recovered from ores by the amalgam process. The metal is recovered by distilling off the mercury . Angstrom An angstrom is a unit of length. A salt that has no water of hydration.