13074231
Description
Flashcards by Kyanna Jackson, updated more than 1 year ago
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Created by Kyanna Jackson
over 6 years ago
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| Question | Answer |
| Radioactivity | results from radioactive decay, which is the process whereby unstable atomic nuclei transform and emit radiation |
| Unstable atomic nuclei | -have an imbalance of neutrons to protons -are radioactive |
| Most radiation we encounter is: | -natural background radiation that originates in Earth and space (cosmic rays from the Sun and stars) -more intense at higher altitudes |
| Three Components of Radiation from Radionuclides | Alpha (α) Beta (β) Gamma (γ) |
| Types of radiation: | -alpha (α) +2 carries positive electrical charge -beta (β) -1 carries negative electrical charge -gamma (γ) carries no charge |
| Alpha particle: | -consist of 2 protons and 2 neutrons (a helium nucleus) -loses energy quickly during interaction -can be stopped easily by a few pieces of paper due to its large mass and double positive charge -is deflected in the presence of magnetic or electric fields |
| Alpha particle: | -does not normally penetrate lightweight material (paper, clothing) -causes significant damage to the surface of a material (living tissue) due to great kinetic energy -picks up electrons and becomes harmless helium when traveling through air |
| Beta particle: | -is an ejected electron -has both a smaller mass and electric charge than an alpha particle, and moves faster -loses energy at a slower rate in air and travels farther before stopping -can be stopped by several sheets of aluminum foil |
| Beta particle: | -penetrates fairly deeply into skin (potential for harming or killing cells) -once stopped, becomes an ordinary electron -is deflected in the opposite direction to an alpha particle in the presence of magnetic and electric fields |
| Gamma rays: | -are high-frequency electromagnetic radiation -are emitted when a nucleus in an excited state moves to a lower energy state -are more harmful than alpha or beta particles -are most penetrating because they have no mass or charge |
| Gamma rays: | -are pure energy, greater per photon than in visible or ultraviolet light and x-rays *are unaffected by magnetic and electric fields, and therefore interact via direct hit with an atom |
| Common Particles Encountered in Nuclear Reactions | |
| alpha particle= | nucleus of the helium atom |
| In a nuclear decay equation, the sums of the mass numbers (A) and the sums of the atomic numbers (Z) will be equivalent on each side | * |
| when an atom undergoes radioactive decay, it | turns into a completely different element |
| The atomic nucleus and the strong number force | the strong force is a force in the nucleus that holds nucleons together |
| the strong force is only between close together nucleons. For far apart protons, the electric force is greater | * |
| Alpha charge: 2+ mass: 4 Beta charge: 1- mass: 0 Gamma charge: 0 mass: 0 Positron charge: 1+ mass: 0 Neutron charge: 0 mass: 1 | |
| Half-Life: | -is the rate of decay for a radioactive isotope -is the time required for half of an original quantity of an element to decay -is constant and independent of any physical or chemical change the atom may undergo |
| Half-Life: | can be calculated at any given moment by measuring the rate of deca of a known quantity using a radiation detector. |
| Decay of Thorium234 over two half-lives Thorium234 has a half-life of 24 days. | 1000g of 234/90Th Day 0 100% Th (First half life) > 50g of other atoms - 50g of 234/90Th Day 24 50% Th (Second half life) > 75g of other atoms- 25g of 234/90Th Day 48 25% Th |
| Finding the Elapsed Time | How long would it take a sample of 14C to decay to one-fourth its original activity? (half life of 14C is 5730 years) 11,460 |
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