Please help...
CaS cation and anion
ZnCl2 cation and anion
Cu2CrO4 cation and anion

Ionic compounds form when positive and negative ions share electrons and form an ionic bond. ... The positive ion, called a cation, is listed first in an ionic compound formula, followed by the negative ion, called an anion. A balanced formula has a neutral electrical charge or net charge of zero.

Explanation:Simple ions:  

PerchlorateClO4-IO3-

ChlorateClO3-BrO3-

ChloriteClO2-  

HypochloriteOCl-OBr-

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.