Chapter 22: Nuclear Chemistry

Alpha Radiation (α)

Consists of helium nuclei (2 protons and 2 neutrons). It has a positive charge and is the least penetrating form of radiation.

Beta Radiation (β)

Consists of high-speed electrons or positrons emitted from a nucleus. It has moderate penetrating power and can be stopped by aluminum.

Gamma Radiation (γ)

High-energy electromagnetic waves with no mass or charge. It has the highest penetrating power and can be reduced by lead or thick concrete.

Positron Emission

The emission of a positron (a particle with the mass of an electron but a positive charge) from a proton in the nucleus, converting it to a neutron.

Electron Capture

A process in which an inner orbital electron is captured by the nucleus and combines with a proton to form a neutron.

Properties of Radiation

• Alpha particles are heavy, slow, and positively charged. They are stopped by paper or skin.
• Beta particles are lighter and faster, with negative or positive charge. They are stopped by thin metal sheets.
• Gamma rays are uncharged and highly penetrating, requiring dense materials like lead for shielding.

Nuclear Equations

Alpha Decay

A process where a nucleus emits an alpha particle, reducing its atomic number by 2 and mass number by 4. ${\mathrm{^A\_ZX}}^{}\to {\mathrm{^(A-4)\_(Z-2)Y}}^{}+{\mathrm{^4\_2He}}^{}$

Beta Decay

A neutron in the nucleus transforms into a proton and emits a beta particle and an antineutrino. ${\mathrm{^A\_ZX}}^{}\to {\mathrm{^A\_(Z+1)Y}}^{}+\beta +\mathrm{\nu ̄}$

Gamma Emission

A nucleus in an excited state releases energy by emitting gamma rays without changing its atomic number or mass number.

Applications of Radiation

• Medical Imaging: Gamma rays are used in PET scans to detect abnormalities.
• Radiotherapy: Targeted radiation is used to kill cancer cells.
• Industrial Uses: Radiation is used for sterilizing equipment and inspecting welds.

Questions for Students

1. Define and compare alpha, beta, and gamma radiation in terms of composition and penetrating power.
2. Write the nuclear equation for the alpha decay of Uranium-238.
3. What happens during beta decay? Include the particles involved.
4. Explain the medical and industrial applications of nuclear radiation.
5. Why is gamma radiation more penetrating than alpha or beta radiation?