7.1 Discrete energy and radioactivity

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Atomic Physics

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73 Terms

1

Atomic Physics

The branch of physics that deals with the structure and properties of atoms, focusing on the nucleus, electrons, and energy levels.

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2

Nuclear Physics

The field of physics that studies atomic nuclei and their interactions, including nuclear reactions and radioactivity.

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3

Nucleus

The central part of an atom that contains protons and neutrons, with a positive charge.

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4

Electrons

Negatively charged particles that orbit the nucleus of an atom in fixed orbits.

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5

Protons

Positively charged particles found in the nucleus of an atom.

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6

Neutrons

Uncharged particles located in the nucleus of an atom.

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7

Energy Levels

Specific orbits around the nucleus where electrons are restricted to occupy in an atom, each corresponding to a different amount of energy.

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8

Hydrogen Atom

The simplest element, consisting of a proton bound to a single electron by the electromagnetic force.

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9

Isotopes

Atoms of the same element with different numbers of neutrons in the nucleus.

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10

Planetary Model

A visualization of the atom where the electron orbits the nucleus similar to planets orbiting the sun.

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11

Quantum Mechanics

The branch of physics that deals with the behavior of particles at the atomic and subatomic levels, explaining phenomena like energy levels and electron behavior.

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12

Charge

A property of matter that can be positive or negative, leading to interactions through electromagnetic fields.

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13

Electromagnetic Field

A field that describes the interactions between charged particles, such as protons and electrons, at a distance.

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14

Energy Levels

Different states of energy that an electron can occupy within an atom, typically represented diagrammatically.

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15

Ground State

The lowest energy level an electron can occupy in an atom, considered the most stable state.

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16

Excited State

When an electron occupies an energy level higher than the ground state, it is said to be in an excited state.

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17

Quantized

Energy levels in atoms are quantized, meaning they can only have discrete finite values.

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18

Photon

A packet or quantum of light energy that can be absorbed by an atom to excite electrons to higher energy levels.

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19

Planck Constant

Denoted by 'h', a fundamental constant in quantum mechanics used to relate the energy of a photon to its frequency.

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20

Wavelength

The distance between successive crests of a wave, in the context of photons, it is related to the energy and frequency of the radiation.

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21

Electron Volt (eV)

A unit of energy commonly used in atomic physics, where 1 eV is equivalent to 1.6 × 10^-19 joules.

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22

Principal Quantum Number (n)

Denoted by 'n', it represents the energy level of an electron in an atom, with higher values corresponding to higher energy levels.

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23

Ionization Energy

The energy required to remove an electron completely from an atom, resulting in the atom becoming ionized.

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24

Singly-ionized helium (He+)

An ionized form of helium that has lost one electron, making it "hydrogen-like" in behavior.

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25

Ground State

The lowest energy state of an atom or molecule.

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26

Photon

A quantum of light or other electromagnetic radiation.

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27

Electromagnetic Spectrum

The range of wavelengths or frequencies over which electromagnetic radiation extends.

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28

Emission Spectra

The spectrum of light emitted by excited atoms or molecules.

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29

Absorption Spectra

The spectrum of light absorbed by atoms or molecules.

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30

Diffraction Grating

A device used to disperse light into its constituent wavelengths.

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31

Fraunhofer Lines

Dark lines in the solar spectrum caused by absorption of specific wavelengths of light by elements in the Sun's atmosphere.

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32

Absorption Spectrum

A continuous spectrum with absorption lines corresponding to the frequencies of light in the emission spectrum of the elements within the substance that is absorbing the light.

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33

Diffraction Grating

A device used to disperse light into its component wavelengths for observation.

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34

Prism

Another device used to disperse light into its component wavelengths for observation.

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35

Photon

A quantum of light; the energy of a photon is directly proportional to its frequency.

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36

Energy Levels

Discrete levels of energy that electrons in an atom can possess.

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37

Radioactive Decay

The process in which an unstable atom changes into a different nuclear configuration by emitting alpha particles, beta particles, or gamma radiation.

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38

Nucleus

The central part of an atom containing protons and neutrons.

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39

Nucleon

A collective term for protons and neutrons in the nucleus of an atom.

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40

Strong Nuclear Force

The force that binds protons and neutrons together in the nucleus, overcoming the electrostatic repulsion between protons.

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41

Nuclide

A distinct atomic nucleus characterized by a specific number of protons and neutrons.

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42

Alpha Particle

A particle emitted during alpha decay, consisting of two protons and two neutrons (essentially a helium nucleus).

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43

Isotope

Nuclides of the same element with the same number of protons but different numbers of neutrons.

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44

Gamma Photon

A high-energy photon emitted during the de-excitation of an excited nucleus.

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45

Beta Emission

The process in which a nucleus decays by emitting a beta particle (electron or positron).

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46

Half-life

The time taken for half of the radioactive nuclei in a sample to decay or for the activity of the sample to decrease by half.

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47

Nuclear Equation

A symbolic representation of a nuclear reaction showing the atomic number and mass number of the particles involved.

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48

Radioactive Decay

The process by which an unstable atomic nucleus loses energy by emitting radiation.

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49

Nucleus

The central part of an atom containing protons and neutrons, with a diameter of about 10^-15 meters.

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50

Isotope

Atoms of the same element with the same number of protons but different numbers of neutrons.

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51

Radioactive Isotope

An isotope with an unstable nucleus that undergoes radioactive decay.

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52

Exponential Decay

The type of decay where the rate of decay is proportional to the number of radioactive nuclei present.

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53

Nuclear Interaction

Processes involving collisions or interactions between atomic nuclei.

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54

Geiger-Müller (G-M) tube

A metal cylinder filled with low-pressure gas used to measure beta and gamma radiation by ionizing the gas, producing a pulse of current that can be measured by a counting circuit.

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55

Spark counter

A device used to detect alpha particles, where a spark jumps between a gauze and a filament when alpha particles ionize the air.

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56

Background count

The reading obtained by a Geiger-Müller tube when connected to its counter and switched on, even in the absence of a radioactive source, measuring the natural radiation present in the environment.

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57

Sievert (Sv)

A unit of radiation that considers the ionizing effects of different radiations, with most people absorbing between 1.5 and 3.5 millisievert per year from background radiation.

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58

Absorption of radiation

The interaction of different radioactive emissions with materials based on their ionizing ability, where alpha, beta, and gamma particles require varying thicknesses of materials to be absorbed.

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59

Alpha particles

Positively charged particles that strongly ionize gases, have a short range in air, and are absorbed by thin paper due to their massiveness and charge of +2e.

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60

Beta particles

Negatively charged particles with a range of several centimeters in air, requiring a few millimeters of aluminum for absorption, lighter than alpha particles with a charge of -1e.

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61

Gamma rays

Electromagnetic waves that interact minimally with matter, necessitating many meters of air or several centimeters of lead for absorption.

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62

Ionizing ability

The capability of radioactive emissions to ionize gases or materials, influencing their range and the materials needed for absorption.

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63

Counting circuit

A circuit that measures the pulse of current produced by ionization in a Geiger-Müller tube, used to quantify the radiation detected.

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64

Nuclide

A nuclide is a nucleus with a specific number of protons and neutrons.

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65

Half-life

Half-life is the time required for the count rate to decrease by half in value or for half of the number of nuclei to decay into nuclei of another element.

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66

Alpha Decay

Alpha decay is a type of radioactive decay in which an atomic nucleus emits an alpha particle, consisting of two protons and two neutrons.

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67

Beta Decay

Beta decay is a type of radioactive decay in which a beta particle (an electron or positron) is emitted from an atomic nucleus.

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68

Gamma Decay

Gamma decay is a type of radioactive decay in which a gamma ray is emitted from an atomic nucleus.

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69

G-M Tube

A Geiger-Muller (G-M) tube is a device used for detecting ionizing radiation.

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70

Background Count Rate

The average count rate detected by a radiation detector when no radioactive source is present.

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71

Count Rate

The number of radiation counts detected per unit time by a radiation detector.

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72
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73
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