Radioactivity Why is Radioactivity Important Our lives are

Radioactivity

Why is Radioactivity Important? • Our lives are affected by radioactivity in many ways. • Helps to detect diseases (MRI and CT scans) • Kills cancer cells. • Generate electricity. *Radioactive materials are also very dangerous!

What is radioactivity? • All elements with atomic numbers greater than 83 are radioactive. • Radioactive elements are isotopes with unstable nuclei (they have too many neutrons). • Radioactive atoms give off energy called nuclear radiation, and matter.

Radioactive atoms give off radiation in different forms: • Alpha Particles (α) • Positively charged. • Release a helium nucleus w/ 2 protons and 2 neutrons. (Mass of atom is reduced by 4 and the atomic number is reduced by 2). • Alpha particles are massive in size but cannot even penetrate a piece of paper (low energy).

• Beta Particle (β) • Negatively charged. • Electrons that are released from an unstable atom. Formed from the decay of a neutron to form a proton and a electron. They are very fast moving b/c electrons have little mass. • Smaller than alpha particles. Can penetrate wood and aluminum, but are stopped by lead.

• Gamma Rays (g or γ) • Discovered by Marie Curie in 1898. • Not made of matter like alpha and beta particles, and do not have a charge. Made up of photons (a type of electromagnetic energy). • Have much more energy than alpha and beta particles. Very dangerous. • Can only be stopped by thick lead or concrete.

Nuclear or Radioactive Decay • Causes an atom of one element to become a different element by reducing its atomic number. Half Life • The amount of time it takes for half the atoms of a radioactive sample to decay. Example: Radium-226 has a half life of 1, 602 years. If you have a 10 gram sample of Radium-226 in a dish after 1, 602 years you would have 5 grams. After another 1, 602 years you would have 2. 5 grams.

Examples of Alpha and Beta Decay: Alpha Particle Decay: • An alpha particle is released in the form of Helium. 226 Ra → 222 Rn + 4α Or 226 Ra → 222 Rn + 4 He Beta Particle Decay: • A neutron is broken into 1 electron (gets released) and 1 proton. 14 C → 14 N + -1 e The Carbon changes into Nitrogen b/c a proton is added. Protons are equal to atomic number. Therefore, the element changes (C→N). The mass stays the same!

Fission • Fission is the splitting of a large nucleus into smaller nuclei. This produces a lot of energy. • Once fission occurs it causes a chain reaction. So, one atom splits into two. Those two atoms split into four. Dangerous: Uncontrolled fission is what causes bombs to explode. Example: nuclear bombs Benefit: Controlled fission is what we use to generate power (electricity). Control rods are used to slow the splitting of the atoms.

Fusion • Fusion is when two smaller nuclei are combined to form a larger nuclei. • Fusion is not yet possible for long periods of time. It is much more powerful than fission, and could quite possibly solve our energy problems.

Nuclear Waste • As useful as fission is, it is also very expensive and produces radioactive waste (very dangerous to living material). • Radioactive waste must be contained and kept away from people, water sources, and usually not kept in areas where earthquakes are a possibility. • Rods used in power plants must be contained.