Video: Selecting the Transition for the Ionization of Hydrogen

Which of the following transitions is the transition that represents the ionization of hydrogen?

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Video Transcript

Which of the following transitions is the transition that represents the ionization of hydrogen?

In the diagram, the horizontal lines labeled with a number are individual energy levels, while the vertical lines indicate a possible transition for an electron from one energy level to another. Each energy level is labeled with a principal quantum number, given the symbol ๐‘›. Each number corresponds to a number of electron shell. The lowest energy level corresponds to the first electron shell. The question tells us that this diagram relates to hydrogen. You may have noticed that this diagram adopts the Bohr model, where thereโ€™s no differentiation between types of orbital in each electron shell. So we have no s, p, d, or f orbitals.

The most obvious meaning for ionization is the conversion into an ion. But generally, in chemistry, we think about ionization as the removal of electrons to form positive ions. This is in contrast to electron affinities where weโ€™re looking at adding electrons to produce negative ions. An atom of hydrogen consists of a single electron bound to a nucleus containing only one proton. When discussing ionization of elements, we assume that their electrons are in their lowest possible energy state, which means that the atom is in the ground state. This means on the diagram, our starting point is with the electron in the ๐‘› equals one shell, where the hydrogen atom is in its ground state.

The ionization of a hydrogen atom involves the removal of that single electron, forming an Hโบ ion and a free electron. But in the Bohr model, energy levels go on forever to the extremes of the universe. So technically, we only class it as complete ionization when the nucleus of the hydrogen atom and the electron from the hydrogen atom are infinitely separated. This hypothetical state is given the principal quantum number โˆž. So this is the energy level where our transition must end, where ๐‘› equals โˆž.

The transition of the five that starts at the ground state and finishes at ๐‘› equals โˆž is this one, c.

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