Radioactive Decay: Alpha, Beta, Gamma

• Radioactive decay occurs when unstable atomic nuclei emit alpha, beta, or gamma radiation to become stable.
• This process allows the nucleus to lose energy and stabilize.
• Radioactive elements typically have atomic numbers greater than 82.

Alpha Particles

• Positively charged and attracted to negative plates.
• Low penetration power, traveling only a few centimeters.
• Easily stopped by paper.

Beta Particles

• Electrons emitted from the nucleus.
• Negatively charged, drawn to positive plates.
• Moderate penetration power, traveling about 1 meter.
• Stopped by thin aluminum sheets.

Gamma Rays

• Electromagnetic waves with no mass or charge.
• Unaffected by charged plates due to the absence of charge.
• High penetration power, traveling long distances.
• Stopped by thick lead or concrete barriers.

Types of Particles

• Alpha particles are denoted as α
• Beta particles are denoted as β
• Gamma particles are denoted as γ
• Gamma radiation, as electromagnetic waves, has no atomic or mass number.

Nuclear Equations

• In nuclear equations, the total mass number and total atomic number must be conserved on both sides.

Half-Life

• Half-life is the time required for half of the radioactive nuclei in a sample to decay.
• It is constant and unaffected by chemical or physical conditions.

Calculating Remaining Mass

• To calculate the remaining mass after a given time, determine how many half lives have elapsed, and divide initial mass of the material by 2 for each half life that has elapsed.

Calculating Time for Decay

• To calculate time, determine how many half lives it takes for a materials starting mass to decay to the desired mass, and then multiply the number of half lives by the half life time to determine the time.

Finding Half-Life

• To determine the half life, determine how many half lives have elapsed between the starting mass and ending mass, and then divide the total time of decay by the number of half lives.

Medical Uses of Radiological Isotopes

• Sterilizing medical equipment
• Cancer treatment
• Diagnostic tracers

Industrial Uses of Radiological Isotopes

• Smoke alarms
• Measuring material thickness, such as paper
• Detecting leaks in pipes

Exam Tips for Radiological Isotopes

• Long half-lives are preferable in smoke detectors because the material doesn't get depleted quickly.
• Alpha radiation is chosen for smoke detectors because it has low travel distance.
• Medical tracers should have half-lives that allow for detection without causing prolonged radiation exposure.