Final answer:
The other particle emitted when radium-223 decays to radon-119 is an alpha particle (He).
Step-by-step explanation:
When radium-223 (Z = 88) decays to radon-119 (Z = 86), the other particle emitted is an alpha particle (He). Alpha decay involves the release of helium ions from the nucleus of an atom. In this decay process, the atomic number decreases by 2, and the mass number decreases by 4. Therefore, the alpha particle is emitted in the decay of radium-223 to radon-119.