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.
1 A physical change, such as a state change or dissolving, does not create a new substance, but a chemical change does. 2  In a chemical reaction, the atoms and molecules that interact with each other are called reactants. 3  In a chemical reaction, the atoms and molecules produced by the reaction are called products.n a physical change, like a state change or dissolving, no new substance is formed. Explain that another way to say that no atoms are created or destroyed in a chemical reaction is to say, âMass is conserved.â. Project the image Balanced Equation.