- Suppose that a newly discovered element called centium has three isotopes that occur in
hese are centium-200, centium-203. and centium-209. Assume that these isotopes
occur in equal amounts in nature. What will be the average atomic mass of this element?

Which best describes the activation energy of a chemical reaction? a. the combined energy of all the reactants b. the amount of energy required for a reaction to occur c. the difference in energy between products and reactants d. the potential energy stored in the bonds of reactants and products