```
E = hf
```
Where:
* E is the energy in Joules (J)
* h is Planck's constant (6.626 × 10^-34 Js)
* f is the frequency in Hertz (Hz)
Given the frequency of the radio station as 1120 kilohertz (kHz), we can convert it to Hertz by multiplying it by 1000:
```
f = 1120 kHz × 1000 = 1,120,000 Hz
```
Now, we can calculate the energy of the radio station:
```
E = (6.626 × 10^-34 Js) × (1,120,000 Hz) = 7.44 × 10^-27 J
```
Therefore, the energy of the radio station that broadcasts at 1120 kilohertz on AM is 7.44 × 10^-27 Joules.