1. Alpha Decay

* Alpha particle emitted: A helium nucleus (²⁴He) containing 2 protons and 2 neutrons.

* Change in atomic number: Decreases by 2.

* Example: Uranium-238 (atomic number 92) decays into Thorium-234 (atomic number 90) by emitting an alpha particle.

2. Beta Decay (Two Types)

* Beta-minus decay: A neutron decays into a proton, an electron (beta particle), and an antineutrino.

* Change in atomic number: Increases by 1.

* Example: Carbon-14 (atomic number 6) decays into Nitrogen-14 (atomic number 7) by emitting a beta-minus particle.

* Beta-plus decay (positron emission): A proton decays into a neutron, a positron (antimatter counterpart of an electron), and a neutrino.

* Change in atomic number: Decreases by 1.

* Example: Potassium-40 (atomic number 19) decays into Argon-40 (atomic number 18) by emitting a positron.

3. Gamma Decay

* Gamma ray emitted: High-energy photon (electromagnetic radiation).

* Change in atomic number: No change in atomic number. Gamma decay only changes the energy state of the nucleus, not its composition.

* Example: Cobalt-60 (atomic number 27) in an excited state can emit a gamma ray to reach a lower energy state, but its atomic number remains the same.

Summary:

* Alpha decay: Atomic number decreases by 2.

* Beta-minus decay: Atomic number increases by 1.

* Beta-plus decay: Atomic number decreases by 1.

* Gamma decay: Atomic number remains unchanged.