If the ion is negatively charged, anion, it means that it gains two
electrons from its surroundings. The number of electrons of an argon (neutral
atom) is 18. Two of the electrons in our anion is from the surrounding, so
originally it only has 16 electrons.
In the periodic table, the 16th element is sulphur. The
chemical symbol of sulphur is S. Thus, the anion is the negatively charged
sulphur with chemical symbol of S2-.
Since the forward reaction is endothermic (heat is consumed in the reaction) that means that the enthalpy change for the forward reaction is a positive value.
Therefore, i would say that the reverse or backward reaction is exothermic (heat is released in the reaction to the sorroundings) and that the enthalpy change is a negative value.
I think this should be true...
As a comet gets closer to the sun, the ice on the surface of the nucleus begins turning into gas, forming a cloud known as the coma. ... Since comet tails are shaped by sunlight and the solar wind, they always point away from the sun.
