Alpha
alpha particles.
The decay is: Th-230-------------Ra-226 + He-4
Thorium 230 has 90 electrons and 140 neutrons.
Thorium 230 has 90 protons and 140 neutrons - the difference is 50.
By alpha decay Th-230 is transformed in Ra-226.
Thorium has 90 protons. So for a neutral atom, there has to be 90 electrons. 230 is the total number of nucleons. ie 90 protons and 140 neutrons.
Thorium-230 decays into radium-226 when it emits an alpha particle.
Thorium 230 is an alpha emitter with half life 75,380 years. Therefore it is dangerous if ingested. Alpha particles don't penetrate the skin, so it would not be dangerous to handle carefully, but if ingested alpha particles can damage internal organs. Thorium 234 is a beta emitter with half life 24.1 days. So 230 is the more dangerous.
The balanced nuclear equation for the alpha decay of thorium-230 is: ^230Th → ^226Ra + ^4He
The atomic number of thorium is 90. So there are 90 protons and 90 electrons. In Th-230 isotope there are 140 neutrons (230 - 90 = 140) So there are 50 more neutrons than the number of protons.
The atomic number of thorium is 90. so it will always have 90 protons in all its isotope.
Thorium has 90 protons. It does not matter which isotope is involved.