Understanding Alpha Decay
* Alpha particles consist of 2 protons and 2 neutrons (essentially a helium nucleus, ⁴₂He).
* Alpha decay occurs when an unstable nucleus emits an alpha particle. This results in:
* A decrease in atomic mass by 4: The alpha particle carries away 4 atomic mass units.
* A decrease in atomic number by 2: The alpha particle carries away 2 protons.
Calculations
* Bismuth-213: Bismuth has an atomic number of 83. So, bismuth-213 has 83 protons and 213 - 83 = 130 neutrons.
* After Alpha Decay:
* Atomic Mass: 213 - 4 = 209
* Atomic Number: 83 - 2 = 81
The Resulting Element
* An element with an atomic number of 81 is thallium (Tl).
Therefore, when bismuth-213 emits an alpha particle, it becomes thallium-209 (²⁰⁹₈₁Tl).
