Im pretty sure the answer is the atmosphere provides warmth.
Atoms 'like' to have 8 valence electrones. sodium has one electron 'in excess' and chlorine 'lacks' in one. so they just exchange :) both are happy. then the ionic bond is formed because chlorine is now charged negative (additional electron) and sodium is charged positive (gave up one electrone) - the opposite charges cause electrostatic pull. many atoms, many bonds and thats how salt is built.
The mixing of Ni(NO3)2(aq) and Na2CO3(aq) will result in a precipitation reaction.
Ni(NO3)2(aq) + Na2CO3(aq) =====> NiCO3(s) + 2NaNO3(aq)
:-) ;-)
