Types of Nuclear Decay ✏ Chemistry In a Nutshell

Rucete ✏ Chemistry In a Nutshell

1. Alpha (α) Decay

• Occurs when an unstable nucleus emits an α particle (Helium nucleus, ⁴₂He).
• Changes in the nucleus:
  • Mass number decreases by 4.
  • Atomic number decreases by 2.
• Key Characteristics:
• Symbol: ⁴₂He or α.
• Contains 2 protons and 2 neutrons (positively charged).
• Relatively slow-moving (~10% of the speed of light).
• Low penetrating power (stopped by paper).
• Can be harmful if inhaled.

2. Beta (β⁻) Decay

• A neutron transforms into a proton and emits an electron (β⁻ particle).
• Changes in the nucleus:
  • Mass number remains the same.
  • Atomic number increases by 1.
• Key Characteristics:
• Symbol: β⁻.
• Faster than alpha decay (~98% of the speed of light).
• Medium penetrating power (stopped by aluminum foil).
• Can ionize gases and be harmful if absorbed by the body.

3. Positron (β⁺) Emission

• A proton converts into a neutron and emits a positron (β⁺ particle, which is the antimatter counterpart of an electron).
• Changes in the nucleus:
  • Mass number remains the same.
  • Atomic number decreases by 1.
• Key Characteristics:
• Symbol: β⁺ or ⁰₁e.
• Positron quickly annihilates with an electron, releasing gamma rays (γ).
• Very short-lived.
• Weak penetrating power.

4. Electron Capture

• An inner orbital electron is captured by the nucleus, causing a proton to convert into a neutron.
• Changes in the nucleus:
  • Mass number remains the same.
  • Atomic number decreases by 1.
• Key Characteristics:
• Symbol: e⁻ capture.
• Leads to the emission of X-ray photons (hv).
• Common in heavy elements.
• Does not emit a particle, only energy.

5. Gamma (γ) Decay

• Occurs when a nucleus loses excess energy by emitting a high-energy photon (γ ray).
• No change in atomic or mass number.
• Key Characteristics:
• Symbol: γ.
• Extremely high penetrating power (stopped only by thick lead or concrete).
• Can pass through human tissue and damage DNA.
• Travels at the speed of light.
• Less ionizing than beta decay but very dangerous due to deep penetration.

In a nutshell

Decay Type	Particle Emitted	Change in Mass Number	Change in Atomic Number	Penetration Power
Alpha (α)	Helium nucleus (⁴₂He)	-4	-2	Low (stopped by paper)
Beta (β⁻)	Electron (e⁻)	0	+1	Medium (stopped by aluminum)
Positron (β⁺)	Positron (⁰₁e)	0	-1	Weak
Electron Capture	No particle (absorbs an electron)	0	-1	Emits X-rays
Gamma (γ)	High-energy photon	0	0	Very high (stopped by lead/concrete)

"Alpha is Air Blocked, Beta Breaks Through, Gamma Goes Everywhere!"

• Alpha is weakest (stopped by paper).
• Beta is stronger (stopped by metal).
• Gamma is the strongest (needs thick shielding).