St. Peter's Square, Vatican City, Vatican, seen through the Balustrade atop the Basilica. Photo by Elisabetta Villa/Getty Images News/Getty Images. Definition: A balustrade is a row of repeating balusters-small posts that support the upper rail of a railing.Staircases and porches often have balustrades. balustrade is a row of repeating balusters-small posts that support the upper rail of a railing.
dissociation, in chemistry, separation of a substance into atoms or ions. Thermal dissociation occurs at high temperatures. For example, hydrogen molecules (H. The Columbia Electronic Encyclopedia, 6th ed. Copyright Â© 2012, Columbia University Press. All rights reserved.
A chemical change is a dissociation, recombination, or rearrangement of atoms. compound Compare with element and mixture. A compound is a material formed from elements chemically combined in definite proportions by mass. For example, water is formed from chemically bound hydrogen and oxygen.ompare with molecule and ion. An atom is the smallest particle of an element that retains the chemical properties of the element. Atoms are electrically neutral, with a positively charged nucleus that binds one or more electrons in motion around it.