In the dissoication of H2 in gas, why is 2 H atoms almost always achieved instead of proton and hydride?
The dissociation of H2 gas into two H atoms, rather than a proton (H+) and hydride ion (H-), is due to the stability and energetics of the process. When H2 dissociates, it involves breaking the covalent bond between the hydrogen atoms. The most favorable pathway for this dissociation involves the simultaneous cleavage of the bond and the redistribution of electrons to form two separate H atoms.
To understand why this pathway is preferred, we need to consider the energetics involved. The bond between the two hydrogen atoms in H2 is a covalent bond, meaning that the electrons are shared between the two atoms. Breaking this bond requires energy. However, once the bond is broken, the two H atoms can form new covalent bonds, resulting in a lower overall energy state. This lower energy state is more stable than the formation of a proton and a hydride ion.
Furthermore, the formation of a proton and a hydride ion would require the uptake or release of an additional electron, resulting in the formation of charged species. This would create an electrostatic repulsion between the positively charged proton and the negatively charged hydride ion, making it energetically unfavorable.
In summary, the formation of two H atoms in the dissociation of H2 gas is favored because it involves breaking and forming covalent bonds, leading to a more stable and energetically favorable outcome compared to the formation of a proton and a hydride ion.