Lattice energy is Question 4 options: the energy given off when gaseous ions combine to form one mole of an ionic solid the energy required to convert a mole of ionic solid into its constituent ions in the gas phase the energy required to produce one mole of an ionic compound from its constituent elements in their standard states the sum of ionization energies of the components in an ionic solid the sum of electron affinities of the components in an ionic solid

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.