Radioactivity Flashcards

Marie Curie

  • Marie Curie, a pioneering scientist, received two Nobel Prizes in different fields.
  • Despite initial resistance, two elements were named after her.
  • She coined the term "radioactive".

Radioactive Decay

  • Radioactive decay is the process by which unstable atomic nuclei lose energy by emitting radiation.
  • Alchemists sought the Philosopher's Stone to turn lead into gold.

Elements and Radiation

  • Elements with an atomic number above 83 emit radiation.
  • Elements like hydrogen and carbon typically do not emit radiation.

Types of Radiation

  • Three basic forms of radiation are alpha, beta, and gamma, named after the first three letters of the Greek alphabet.
    • Alpha particle.
    • Beta particle.
    • Gamma ray.
  • Gamma rays differ from X-rays.

Alpha Particles

  • An alpha particle is essentially a helium nucleus (He^{2+}).
  • It has a positive two charge (+2).

Beta Particles

  • A beta particle is an electron emitted from the nucleus.
  • It has a negative one charge (-1).
  • All these particles are emitted from the nucleus, not the electrons themselves.

Gamma Rays

  • Gamma rays are high-energy radiation with no mass.

Other Particles Involved in Radioactivity

  • Positrons and neutrons are also involved in radioactivity.
  • James Chadwick discovered the neutron in 1932, leading to the development of atomic bombs.

Positrons

  • A positron has a positive charge (+1) and is the antiparticle of the electron.

Neutrons

  • A neutron is neutral with no charge.

Alpha Decay

  • Alpha decay can be represented as:
    • {^{A}{Z}X \rightarrow {^{A-4}{Z-2}Y} + {^{4}_{2}He}}
  • Example:
    • {^{235}{92}U \rightarrow {^{231}{90}Th} + {^{4}_{2}He}}
  • In alpha decay:
    • The mass number decreases by 4.
    • The atomic number decreases by 2.
  • Both sides of the equation must balance.

Beta Decay

  • Neutrons in the nucleus can break down into a proton and an electron (beta particle).
  • Example:
    • {^{231}{90}Th \rightarrow {^{231}{91}Pa} + e^- + \bar{\nu}_e}
  • Where Pa is Protactinium.
  • The new element has an atomic number one greater than the original element.
  • Both sides of the equation must be equal, meaning, the sum of atomic numbers and mass numbers must be conserved.
  • Electrons are emitted during beta decay.

Gamma Rays and Energy Emission

  • Gamma rays are emitted when a reaction occurs, releasing extra energy.
  • Gamma rays have higher energy than X-rays, causing more damage.

Positron Emission

  • Positrons are the opposite of electrons and have a +1 charge.
  • They originate from protons.
  • Electron emission leads to the emission of gamma rays.
  • PET (Positron Emission Tomography) scans use positron emission for diagnostic purposes.
  • PET scans can reveal differences in brain patterns between smokers, alcoholics, and cocaine users.

Neutrons in Radioactive Decay

  • Neutrons (10n) are used to force elements to undergo radioactive decay.

Biological Effects of Radiation

  • Alpha and beta particles, being relatively large, cause ionization by knocking off electrons when they interact with the body.
  • Ionizing radiation can cause cancers and affect genetic material.

Ionizing Radiation

  • Ionizing radiation ejects electrons, creating positively and negatively charged ions.