Radiography - Ch. 3, 4
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86 terms
Terms | Definitions |
|---|---|
 believed elements composed of identical atoms that reacted the same way chemically; visualized as being an 'eye-and-hook' affair | Dalton |
| greek scientists thought all matter was composed of these four substances | earth, water, air, fire |
| described atom as something looking like 'plum pudding'; plums represented negative electric charges and pudding was shapeless mass of uniform positive electrification | Thomson |
| total number of elements identified today | 112 (92 natural, 20 artifically produced) |
| first to describe the 'nuclear model' and call center of atom the 'nucleus' | Rutherford |
| three fundamental particles of the atom | electron, proton, neutron |
| atom's mass unit | amu (atomic mass units) |
| the atom is essentially empty _________ | space |
| term for number of protons in the atom | atomic number (Z) |
| in their normal state, atoms are electrically ________ ; the electric charge of the atom is zero | neutral |
| four essences modifying matter (Greek idea) | wet, dry, hot, cold |
| electron shells are given codes ________ | K, L, M, N, O, P, Q |
| if an atom has extra electrons or has had an electron removed, it is said to be ________ | ionized |
| neutral atom has same number of ... | protons in nucleus as electrons in orbit |
| number of protons determines the atoms ________ | chemical element |
| in all except the ________ atoms, the number of neutrons is always greater than the number of protons | lightest |
| showed that if elements arranged in order of increasing atomic mass, a periodic repetition of properties occurred | Mendeleev |
| physicists call the shell number 'n' the ________ ________ ________ | principal quantum number |
| the larger the atom, the ________ the abundance of neutrons over protrons | greater |
| described atom as miniature solar system in which electrons revolved about nucleus in 'energy levels' | Bohr |
| no outer shell can have more than ________ electrons | eight |
| outermost electron shell (its letter) is equal to its ________ in the periodic table | period |
| formula for maximum number of electrons per shell | (two n squared) 2n(2) |
| 'center-seeking' force; orbiting electrons attracted to protons in nucleus | centripetal force |
| number of electrons in outermost shell of electron is equal to its ________ in the periodic table | group |
| ________ is the removal of orbital electrons from an atom | ionization |
| 'flying-out-from-center' force; electrons maintain distance from nucleus | centrifugal force |
| the closer an electron is to the nucleus, the ________ it is bound | tighter |
| atoms that have same number of neutrons but different number of protons | isotones |
| (A) - (Z) = | number of neutrons |
| atoms of various elements may combine to form structures called | molecules |
| term for protons plus neutrons | atomic mass (A) |
| a chemical ________ is any quantity of one type of molecule | compound |
| atoms that have same atomic number (protons) and same atomic mass number (neutrons) but difference in nucleon arrangement | isomers |
| atomic mass number and precise mass of atom (are/are not) equal | are not |
| atomic nuclei that have same atomic mass number but different atomic numbers (different protons, different neutrons) | isobars |
| the smallest particle of an element is an ________; the smallest particle of a compound is a ________ | atom; molecule |
| atoms that have same atomic number (protons) but different atomic mass (neutrons) | isotopes |
| after electron is ejected (during beta emission), what undergoes a conversion | neutron undergoes conversion to a proton |
| result of beta emission is to increase ________ by one, while atomic mass ________ | atomic number (thus becoming a different element); stays the same |
| some atoms exist in abnormally excited states; to reach stability, the nucleus spontaneously emits particles and energy and transforms itself into another atom; this process is called ________ | radioactive disintegration or radioactive decay |
| ________ is the emission of particles and energy in order to become stable | radioactivity |
| uranium decays to ________, which in turn decays to ________ | radium; radon |
| what is created in and ejected from the nucleus during beta emission | an electron |
| which occurs more frequently - alpha or beta emission | beta |
| alpha particle travels with ________ velocity through matter; has ________ mass and charge; ________ looses its energy | high; great; quickly |
| term for radioactive isotopes | radioisotopes |
| time required for a quantity of radioactivity to be reduced to one-half its original value | half-life |
| two types of ionizing radiation | particulate and electromagnetic |
| types of radiation used in diagnostic ultrasound and in magnetic resonance imaging are _________ radiation | nonionizing |
| alpha emission, a violent process, consists of ________ bound together | two protons and two neutrons (thus an atomic mass of 4) |
| two main types of particulate radiation | alpha particles and beta particles |
| alpha particles are emitted only from ________ | nuclei of heavy elements |
| alpha particle is equivalent to a helium nucleus and contains ________ | two protons and two neutrons |
| alpha particle has a very ________ range in matter; is nearly ________ from an external source because its energy is deposited in superficial layers of skin | short; harmless |
| x-rays and gamma rays are often called ________ and have ________ mass or charge | photons; no |
| beta particles have a _______ range than alpha | longer |
| gamma rays are emitted from the ________ of a radioisotope; x-rays are produced outside the nucleus in the ________ shells | nucleus; electron |
| beta particles are ________ particles with an atomic mass of ________ and carry one unit of ________ or ________ charge | light; zero; negative or positive |
| positive beta particles are called ________ and are considrered to be ________ | positron; antimatter |
| only difference between electrons and beta particles is their ________ | origin |
| beta particles originate in the ________ of _________ atoms | nuclei; radioactive |
| is one-half the range from crest to valley over which the sine wave varies (height) | amplitude |
| photon radiation _______ intensity with distance but theoretically never reaches zero | looses |
| only difference between x-rays and gamma rays is their ________ | origin |
| alpha particles as an internal source of radiation can ________ irradiate the local tissue | intensely |
| an x-ray ________ is a quantum of electromagnetic energy | photon |
| velocity (speed) of all electromagnetic radiation is ________ | the speed of light |
| is the number of wavelengths that pass a point of observation per second (rate of rise and fall) | frequency (f) |
| electromagnetic wave equation | c = f(lambda) .... speed of light = frequency times wavelength |
| visible light is identified by ________, RF is identified by ________, and x-rays are identified by _______ | wavelength; frequency; energy |
| photons interact with matter most easily when the matter is approximately _______ the photon wavelength | the same size as |
| at a given velocity, wavelength and frequency are ________ proportional | inversely |
| the distance from one crest to another, from one valley to another, or from any point on the sine wave to the next corresponding point | wavelength (lambda [upside down y]) |
| the wave equation | v = f(lambda) .... velocity = frequency times wavelength |
| the ________ spectrum includes the entire range of electromagnetic energy | electromagnetic |
| visible-light photons tend to bahave more like _______ than ________ | waves; particles |
| electromagnetic energy _______ is the reduction in intensity that results from scattering and absorption | attenuation |
| x-ray photons tend to behave more like _______ than ________ | particles; waves |
| energy of a photon is ________ proportional to its frequency | directly |
| inverse square law can be applied to distances greater than ________ times the longest dimension of the source | seven |
| the x-ray photon is a discrete bundle of ________ | energy |
| inverse square law | I1/I2 = d2(squared)/d1(squared) ...... intensity 1 divided by intensity 2 = distance 2 (squared) divided by distance 1 (squared) |
| diagnostic ultrasound (is/is not) part of the electromagnetic spectrum | is not |
| electromagnetic energy (radiation) intensity is ________ related to the square of the distance from the source | inversely |
| energy of a photon is ________ proportional to its frequency | directly |
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