4160076
Description
Flashcards by alison_whiteman, updated more than 1 year ago
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Created by alison_whiteman
almost 9 years ago
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| Question | Answer |
| Transmutation | atoms being converted to atoms of another element |
| Nuclide | particular nucleus (specific composition) *each isotope of an element has a different nuclide* |
| Notation for neutron | 1 N 0 |
| Notation for proton | 1 P 1 |
| Notation for an electron | 0 e -1 |
| Radioactive Decay | when a nuclide is unstable and spontaneously emits radiation |
| What does NOT affect the intensity of radiation? | temperature, pressure, or other physical and chemical conditions |
| Alpha Particles | α |
| Beta Particles | high-speed electrons; β |
| Gamma rays | very high-energy photons; γ |
| What happens when a nuclide decays? | forms a daughter nuclide of lower energy |
| Alpha decay | loss of an α particle from the nucleus; A decreases by 4 and Z decreases by 2 in the daughter nuclide |
| Beta decay | ejection of a β- particle from the nucleus; a neutron is converted to a proton and a β- particle is expelled; Z increases by 1 unit |
| Positron emission | β+ particle is emitted from the nucleus; proton is converted to a neutron and a positron is emitted; Z decreases by 1 unit |
| Positron | the antiparticle of the electron |
| Electron capture | occurs when the nucleus interacts with an electron in a low atomic energy level; proton is transformed into a neutron |
| Gamma emission | the radiation of high-energy Y photons; usually occurs together with other forms of radioactive decay; different Y photons of different energies can be emitted as the nucleus returns to group state |
| What two factors determine the stability of a nuclide? | 1. the number of neutrons (N), the number of protons (Z), and their ratio (N/Z) 2. the total mass of the nuclide |
| Band of stability | produced by a plot of numbers of neutrons vs. number of protons for all stable nuclides |
| As Z increases, the N/Z for a stable nuclei gradually _________. | increases |
| All nuclides with Z > ___ are unstable | 83 |
| If the N/Z ratio is too HIGH... | neutrons are converted to protons via beta decay |
| If the N/Z ratio is too LOW... | protons are converted to neutrons via positron emission or electron capture |
| Electrostatic Repulsive Forces | protons experience these forces within the nucleus which destabilize the nucleus |
| Strong Force | exists between all nucleons, contracts the weaker repulsive forces |
| What leads to greater stability? | the pairing of spins between nucleons |
| Elements with an _____ number of protons (Z) have a larger number of stable nuclides | even |
| Nuclide type: neutron-rich Description: high N/Z Mode of Decay: β- decay (lowers N/Z) | .. |
| Nuclide type: proton-rich Description: low N/Z Mode of Decay: β+ emission or e- capture (increases N/Z) | . |
| Nuclide Type: heavy nuclides Description: Z > 83 Mode of Decay: α decay (reduces both Z & N | . |
| Decay Series | when all of the radioactive nuclides that are produced one after the other until a stable nuclide is made |
| What are three ways to detect radioactivity? | 1. can expose light-protected films 2. can ionize the air 3. give off flash of light when interacting with specific chemicals |
| 1 Ci (curie) = 3.70e10 d/s | measures radioactivity |
| The rate of radioactive decay (activity-A) is proportional to the ________. | number of nuclei present (N) A=kN |
| Radioactive decay follows ________ | first-order kinetics |
| rate constant = ___________ | decay constant (k) |
| The larger the k value, the _________ the activity of the substance | higher |
| Half-Life | the time taken for half the nuclei in a sample to decay ln(Nt/N0)=-kt Nt=N0e-kt ln(N0/Nt)=kt |
| Half-Life of 14C | t1/2=ln2/k |
| Radioisotopes | can be used to determine the ages of certain objects |
| Radiocarbon Dating | measures the relative amounts of 14C and 12C in materials of biological origin |
| The mass of the nucleus is less than.... | the combined masses of the nucleons |
| Mass always __________ when nucleons form a nucleus | lost (the lost mass is released as energy) |
| Nuclear Binding Energy | energy required to break 1 mol of nuclei into individual nucleons |
| Electron Volt (eV) | way to express binding energy |
| nucleus + nuclear binding energy --> nucleons | , |
| 1 amu = 931.5e6 eV = 931.5 MeV | . |
| The binding energy/nucleon peaks at elements with a mass number ________. | A = 60 (nuclides become more stable with increasing number up to around 60 nucleons, after which stability decreases) |
| Nuclear Fission | - heavier nucleus splits into lighter ones using neutron bombardment to start the process -releases energy and generates more high-energy neutrons, which causes further fission to occur -the fission process becomes self-sustaining by a chain reaction |
| Nuclear Fusion | -lighter nuclei can combine to form a heavier nucleus -requires high energy input to initiate the process - |
| Critical Mass | mass required to achieve a self-sustaining chain reaction |
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