What is the first decay product of radium?

Answer 1

Radium decays in any of (at least) four different ways, depending on isotope and, in some cases, on luck, as some isotopes can decay in different ways.

The most important way radium can decay is by alpha emission. Nearly all naturally occurring radium decays this way, and so do the majority of synthetic isotopes. In this case, radium emits an alpha particle, which can be regarded as a helium nucleus, and the daughter atom is radon. The isotope of radon is depends on the isotope of radium involved; the mass number of the radon is always equal to the mass number of the radium minus four.

Some heavier radium isotopes undergo negative beta decay, in which case the decay products are an actinium atom and a negative beta particle, which can be viewed as an electron.

Some lighter radium isotopes undergo positive beta decay, in which case the decay products are a francium atom, a positive beta particle, which can be viewed as a positron, and an electron type antineutrino.

A few radium isotopes also rarely undergo what is called cluster decay, and the most important naturally occurring isotope, radium-226 is among these. Cluster decay involves emission of a nucleus larger than an alpha particle, and in the case of radium all known cluster decays emit carbon-14 nuclei. In this case, the daughter atom is lead, with a mass number that is 14 lower than the mass number of the parent. So radium-226 can emit a carbon-14 nucleus, leaving a lead-212 atom.