Question

Why does electromagnetic radiation in the ultraviolet region represent a larger energy transition than does radiation in the infrared region?

Answer 1

I would say for the frequency dependence of the emitted photon during the transition.

Explanation:

During a transition between allowed orbits an electron emits the extra energy in form of a photon of energy:
`E=hf`
where:
`h` is a constant (Planck's Constant;
`f` is the frequency.
You can imagine this photon as a packet of energy bigger or smaller depending on the frequency:
The higher the frequency the larger the energy.
UV radiation has higher frequency than infrared so its energy (carried by the correspondent photon) is higher.
A transition that involves a large amount of emitted energy will result in a high frequency photon.

Hope it is not too confusing!