A catalyst up a reaction. The catalyst [?] permanently changed by the reaction. A catalyst serves as a binding site for a reaction. Reactants are adsorbed onto a catalyst surface. They stick onto the catalyst surface. They then break into their component as their intramolecular break. The loosened atoms can then bond with other atoms to form a . In other words, they can react. The catalyst allows this reaction to occur more easily than if it wasn’t there. Reactants can only bond with one another if they can hit against one another with enough force and the right positioning to stay together. We say they need energy in order to start them reacting. But if a holds the reactants in place to make reacting easier, the reactants need not hit against one another with as much force as if they hadn’t been held in place correctly. In other words, a catalyst [?] the activation needed to cause a reaction. Because of this, the reaction will occur more quickly with a catalyst than without one. We can think of a catalyst as providing a [?] energy pathway for the reaction: as if the reaction was like climbing a high mountain, but the catalyst provides an easier path across the mountain: a path that does not go all the way up and down the mountain top.