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62 Cards in this Set
- Front
- Back
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Who discovered x-rays?
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Wilhelm Roentgen,1896
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Who coined the term RADIOACTIVITY?
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the curies
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Which rays have the greatest penetrating power?
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gamma rays
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What is the origin of radiation?
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Earth & in space
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Is radioactivity on Earth relativity new?
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no, here long before humans
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what is a REM?
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a unit for measuring the ability of radiation to harm living tissue
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What is a radioactive tracer?
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radioactive isotopes incorporated into molecules whose location can then be traced by the radiation they emit
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How are radioactive isotopes used in medical imaging?
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NaI is administered to a patient & traced through the body with a radiation detector.
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How are the strong nuclear force & electric force different from each other?
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STRONG NUCLEAR FORCE - the force of interaction between all nucleons, effective only at extremely close distances
ELECTRIC FORCE- reulsive |
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What role do neurons play in the atomic nucleus?
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"nuclear cement" - holding the atomic nucleus together
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Why is there a limit to the number of neutrons a nucleus can contain?
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nucleons must practically be touching in order for the force to remain strong
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What change in atomic numbers occurs when a nucleus emits an alpha particle? a beta particle?
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alpha - nucleus -2 protons& -2 neutron
beta - -1neutron & +1 proton |
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what is the fate of uranium?
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it will ultimately become lead
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what is meant by the half-life of a radioactive sample?
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half the atoms in a plant/animal will decay in X yrs, then half of those atoms will decay in the number of X yrs
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Half-life of radium-226?
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1620
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How does the decay rate of an isotope relate to its half-life?
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half-life can be measured by rate of decay
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more radioactive - carbon-12 or carbon-14?
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carbon-14
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Why is there more carbon-14 in living bones than in once-living ancient bones in the same mass?
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when an animal dies, replenishment of carbon-14 stops
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Why is lead found in all deposits of uranium ores?
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uranium decays to become lead
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Is a chain reaction more likely to occur in 2 separate pieces of uranium-235 or in the same pieces stuck together?
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same pieces stuck together - reaction requires a large chunk
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why does a chain reaction not occur in uranium mines?
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any chain reaction is snuffed out by the neutron-absorbing uranium-238 & other neutron-absorbing elements
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is a chain reaction more likely to occur in two separate pieces of uranium-235 or in the same pieces stuck together?
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same pieces stuck together - reaction requires a large chunk
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How is a nuclear reactor similar to the furnace in a fossil fuel power plant? how is it different?
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a nuclear reactor = nuclear boiler at plant
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When two hydrogen isotopes are fused, is the mass of the product nucleus more or less than the total mass of the hydrogen nuclei?
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less
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from where does the sun get its energy?
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thermonuclear fusion
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how do the products of fusion reactions differ from the products of fission reaction?
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FUSION - joins together; releases energy
FISSION - splitting; releases energy |
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if a baseball were the size of the earth, about how large would its atoms be?
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the size of ping-pong balls
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when we use a scanning probe microscope, do we see atoms directly or do we see them only indirectly?
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indirectly
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why are atoms invisible to visible light?
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light travels in waves & atoms are smaller than the wave lengths of visible light
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what is the difference between a physical model & a conceptual model?
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PHYSICAL - object
CONCEPTUAL - system |
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Does the visible light constitute a large or small portion of the electromagnetic spectrum?
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very small portion
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why does ultraviolet light cause more damage to our skin than visible light?
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shorter wavelengths & higher frequencies
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as the frequency of light increases, what happens to its energy?
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increases
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what does a spectroscope do to the light coming from an atom?
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observe
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what causes an atom to emit light?
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forms of energy (heat/electricity)
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why do we say atomic spectra are like fingerprints of the elements?
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its how you identify the pattern of frequencies
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what did rydberg note about the atomic spectrum of hydrogen?
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the orderliness that existed
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what is a photon?
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single quantum of light
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which has more potential energy: an electron close to an atomic nucleus or one far from an atomic nucleus?
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far from nucleus
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what happens to an electron as it absorbs a photon of light?
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absorbs energy
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did Bohr think of his planetary model as an accurate representation of what an atom looks like?
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no,just a "crude beginning"
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about how fast does an electron travel around the atomic nucleus?
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2 million meters per second
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Who developed the equation that relates the intensity of an electron's wave to the electron's most probable locatin?
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BOHR
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How many electrons may reside in a single orbital?
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two
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1s^2
2s^2 2p^6 |
carbon
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Which electrons are most responsible for the physical & chemical properties of an atom?
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outermost electrons
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What do the orbitals in a shell have in common?
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comparable energies
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How many orbitals are there in the third shell?
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8
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How is the number of shells an atom of a given element contains related to the row of the periodic table in which that element is found?
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elements in the same period have electrons in the same shells
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How would you know from looking at the periodic table that Oxygen (a # 8) molecules are smaller than Nitrogen (a # 7) molecules?
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the atoms to the right are smaller
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what is an effective nuclear charge?
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nuclear charge experienced by outer-shell electrons, diminished by the shielding effect of inner-shell electrons
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Based on the trend of atomic diameter which should be larger: an atom of Tc (a# 43) or an atom of Ta (a# 73)?
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Ta - larger bc closer to the bottom
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How many shells are needed to account for the seven periods of the periodic table?
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seven
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how many electons can fit in the first shell? second shell?
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2; 8
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how many shells are completely filled in an argon atom, Ar (a# 18)?
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3
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which electrons are represented by an electron-dot structure?
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valence electrons
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how many nonbonding pairs are there in the valence shell of an oxygen atom?
how many unpaired valence electrons? |
2;2
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how does an ion differ from an atom?
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an ION is an ATOM having a net electrical charge
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to become a negative ion, does an atom lose or gain electrons?
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loss
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which elements tend to form ionic bonds?
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two oppositely charged ions
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what is the electric charge on the calcium ion in the compound calcium chloride, CaCl2?
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negative
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what force holds two atoms together in a covalent bond?
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mutual attraction
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