What are the two types of radioactive decay?

Answer 1

It can be argued that they all can:

Alpha is emission of helium nucleus - a loss of four nucleons. Clearly a new nuclide.

Beta decay converts a proton into a neutron or vice-versa, with subsequent emission of a positron or electron, respectively (plus a neutrino). This decay maintains total mass number as one nucleon turns into another, but the proton (or atomic) number changes by +/- 1. This therefore produces a different nuclide.

Gamma is a bit different as it's usually emitted along with alpha or beta decay. However, there are many cases of "isomers." These are unstable nuclei that emit gamma radiation, known (in this case) as isomeric transition (IT). IT is distinguished from "normal" gamma emission by the relative stability of the unstable nuclide - usually referred to as a metastable nuclide. An isomer is stable enough to have its own half-life calculated. Metastable nuclides are labelled as such with an "m" following the mass number - e.g. Kr-81m, Tc-99m and In-113m.

Also see this decay scheme as an example:

Mo-99 (T_1/2 ~3 days)

-> Tc-99m (T_1/2 ~ 6 hr)

-> Tc-99 (T_1/2 2e5 yr)

-> Rb-99 (stable)

So I reckon the short answer is alpha, beta AND gamma.

Answer 2

Alpha decay occurs because the nucleus has too many protons which cause excessive repulsion. In an attempt to reduce the repulsion, a Helium nucleus is emitted. The way it works is that the Helium nuclei are in constant collision with the walls of the nucleus and because of its energy and mass, there exists a nonzero probability of transmission.

Answer 3

The three natural types of Radioactive decay are Alpha, Beta, and Gamma. Alpha is the most ionising of the three, but the least penetrative, Gamma is the most penetrative but the least ionising.

Answer 4

-Beta decay, which emits an electron

-Alpha decay, which emits an alpha particle (4,2 He 2+)

-Gamma decay, which emits gamma radiation (no change in atomic particles)

Answer 5

I assume you're referring to alpha and beta radiation.

Answer 6

Alpha, Beta, Positron emission, elecron capture.