Why the reaction between alkali metals and water exothermic?? I know that it produces heat to surroundings But, what actually happens?? Why it gives heat to surroundings?? http://antoine.frostburg.edu/chem/senese/101/thermo/faq/exothermic-endothermic-examples.shtml says that when forming ion pairs (like ionization reaction), it is endothermic (since it needs some heat to get the electron out) But, the reaction between alkali metals and water is 2M(s) + 2H2O(l) => 2M+(aq) + 2OH−(aq) + H2(g) Which forms ions pair.. But, it's not endothermic, but exothermic.. Why???