Jorge is studying the history of the periodic table. Since 1869, the periodic table has been revised as new elements have been identified. In the modern periodic table, which of the following describes atoms with similar chemical behavior and properties? They have similar atomic masses They are located within the same group They are located within the same period They have the same number of isotopes

chemical changes occur when a substance combines with another to form a new substance, called chemical synthesis or, alternatively, chemical decomposition into two or more different substances. these processes are called chemical reactions and, in general, are not reversible except by further chemical reactions. some reactions produce heat and are called exothermic reactions and others may require heat to enable the reaction to occur, which are called endothermic reactions. understanding chemical changes is a major part of the science of chemistry.