Q&A Hero

Q: Radium-226 is a common isotope on Earth, but has a half-life of about 1600 years. Given that Earth is some 5 billions years old, why is there any radium at all? A) Radium-226 is one of several self-transmutating isotopes of the elements of the periodic table and is able to replenish itself so that it is never depleted. B) Radium-226 and Radium-218 undergo a series of transmutation reactions of alpha and beta decay to repeatedly become one another approximately every 1600 years. C) Radium-226 is a "daughter" isotope and the result of the radioactive decay of uranium. D) Radium-226 and Astatine-218 are converted back and forth via transmutation to one another at each of their respective half-life cycles.

Q: Why wouldn't you use carbon-14 dating on a piece of shell that was estimated to be 1 million years old? A) Sea shells do not have radioisotopes. B) Carbon dating is only useful on plants. C) Uranium dating is better for items older than 1/2 million years. D) Carbon dating can only be used on items that were once alive. E) The amount of radioactive carbon in the sample would probably too small to measure.

Q: Which of the following statements about carbon-14 dating is true? A) Carbon-14 dating is very accurate because the amount of carbon-14 in the atmosphere is constant. B) Carbon-14 can be used to date anything younger than 50,000 years. C) Carbon-14 dating can be used to date stone tools as well as bone. D) all of the above E) none of the above

Q: The half-life of carbon-14 is 5730 years. A sample is found to have one-eighth the original amount of carbon-14 in it. How old is the sample? A) 5730 years B) 716 years C) 45,800 years D) 17,200 years E) none of the above

Q: How can a half-life be used to tell the age of a sample? A) The half-life of an isotope is constant. B) The amount of radioactive form depends on the amount of radiation in the surroundings. C) The ratio between the radioactive form and the stable form depends on the archaeological record. D) The ratio between the radioactive form and stable form varies regularly with time. E) both C and D

Q: How come an animal's carbon-14 levels do not start to decrease until it dies? A) because it constantly replenishes its carbon-14 supply by eating plants with carbon-14 in them B) because it constantly replenishes its carbon-14 supply by breathing air with carbon-14 in it C) because it is constantly being bombarded with cosmic rays D) carbon-14 only starts to decay after the animal dies E) the carbon-14 levels do not decrease because the carbon-13 in its skin protects it from cosmic rays

Q: If Uranium-234 decays via alpha emission, what is the likely product of radioactive decay? (U, atomic no. = 92) A) Th B) Np C) Th D) Np E) none of the above

Q: If a nucleus of Th absorbs a neutron and the resulting nucleus undergoes two successive beta decays (emitting electrons), what nucleus results? A) americium-232 B) plutonium-232 C) thorium-233 D) uranium-233

Q: How many alpha particles are emitted in the series of radioactive decay events from a U-238 nucleus to a Pb-206 nucleus? A) 32 B) 16 C) 8 D) 4

Q: Elements above uranium in the periodic table do not exist in any appreciable amounts in nature because they have short half-lives. Yet there are several elements below uranium in atomic number with equally short half-lives that do exist in appreciable amounts in nature. How can you account for this? A) These are isotopes formed by living bodies. B) These isotopes were placed in nature by the testing of nuclear bombs. C) These isotopes were formed from the fusion of even smaller isotopes. D) These isotopes result from the radioactive decay of uranium.

Q: How is it possible for an element to decay "forward in the periodic table"that is, to decay to an element of higher atomic number? A) When the decay is instigated by a collision with a proton. B) As a beta particle is released, a neutron transforms into a proton. C) This only occurs during nuclear fusion. D) It is not possible. Radioactive decay always results in an isotope with the same or lower atomic number.

Q: When Po emits a beta particle, it transforms into a new element. What are the atomic number and atomic mass of this new element? A) atomic number = 84; atomic mass = 219 B) atomic number = 86; atomic mass = 214 C) atomic number = 85; atomic mass = 218 D) atomic number = 82; atomic mass = 214

Q: When Ra decays by emitting an alpha particle, what is the atomic number of the resulting nucleus? What is the resulting atomic mass? A) atomic number = 86; atomic mass = 222 B) atomic number = 87; atomic mass = 226 C) atomic number = 86; atomic mass = 224 D) atomic number = 87; atomic mass = 224

Q: When the isotope bismuth-213 emits an alpha particle, what new element results? A) lead B) platinum C) polonium D) thallium

Q: Which type of radiationalpha, beta, or gammaresults in the least change in atomic number? A) alpha radiation B) beta radiation C) gamma radiation D) They all result in the same change in atomic mass number.

Q: Which type of radiationalpha, beta, or gammaresults in the greatest change in atomic mass number? A) alpha radiation B) beta radiation C) gamma radiation D) They all result in the same change in atomic mass number.

Q: If carbon-14 is a beta emitter, what is the likely product of radioactive decay? A) nitrogen-14 B) carbon-12 C) oxygen-18 D) berrylium-10 E) none of the above

Q: Which type of radiation is being emitted in the following incomplete nuclear equation?Po -> Pb + ??A) alphaB) betaC) gammaD) A and BE) none of the above

Q: Which type of radiation is being emitted in the following incomplete nuclear equation?Pb -> Bi + ??A) alphaB) betaC) gammaD) A and BE) none of the above

Q: Complete the following nuclear equation:?? -> At + eA) RaB) AtC) PoD) RnE) none of the above

Q: Complete the following nuclear equation:?? -> Rn + HeA) RaB) AtC) PoD) RnE) none of the above

Q: Complete the following nuclear equation:Po -> ?? + HeA) PoB) PbC) PbD) RnE) none of the above

Q: Complete the following nuclear equation:Bi -> ?? + eA) PoB) PbC) PbD) ThE) none of the above

Q: Complete the following nuclear equation:Bi -> Tl + ??A) eB) HeC) gamma rayD) both A and BE) none of the above

Q: Complete the following nuclear equation:Tl -> Pb + ??A) eB) HeC) gamma rayD) both A and BE) none of the above

Q: Which of the following nuclear equations correctly describes alpha emission?A) Th -> Pa + eB) Th -> Ac + eC) Th -> Pa + eD) Th -> eE) none of the above

Q: Which of the following nuclear equations correctly describes beta emission?A) Th -> Pa + eB) Th -> Ac + eC) Th -> Pa + eD) Th -> eE) none of the above

Q: Which of the following nuclear equations correctly describes beta emission?A) U -> Th + HeB) U -> U + HeC) U -> Pu + HeD) U -> HeE) none of the above

Q: Which of the following nuclear equations correctly describes alpha emission?A) U -> Th + HeB) U -> U + HeC) U -> Pu + HeD) U -> HeE) none of the above

Q: What is transmutation? A) changing one element into another by adding or removing protons from the nucleus B) changing one element into another by adding or removing electrons from the nucleus C) changing one element into another by adding or removing neutrons from the nucleus D) a process that emits radiation E) alteration in DNA due to radioactivity

Q: If three samples have the half-lives listed below, which sample would remain radioactive the longest? A) a sample with a half-life of 20 minutes B) a sample with a half-life of 20 hours C) a sample with a half-life of 20 years D) a sample with a half-life of 20 million years E) none of the above

Q: If three samples have the half-lives listed below, which is the most radioactive? A) a sample with a half-life of 20 minutes B) a sample with a half-life of 20 hours C) a sample with a half-life of 20 years D) a sample with a half-life of 20 million years E) none of the above

Q: If a material has a half-life of 24 hours, how long do you have to wait until the amount of radioisotope is 1/4 its original amount? A) 12 hours B) 24 hours C) 48 hours D) 72 hours E) practically forever, but it may be safe by then

Q: What property of half-lives makes radioactive material so problematic? A) There is no known way to shorten a half-life. B) Radioactivity is limited by the natural decay-time to stable isotopes. C) All half-lives are long. D) There is no known way to measure half-lives with any accuracy. E) both A and B

Q: What is a half-life? A) It is the time it takes for 1/2 of the material to undergo radiodecay. B) It is the time needed until 1/2 of the radiation is gone. C) It is the time it takes for 1/2 of the material to decompose. D) It is half of the lifetime of the radioactivity in a sample. E) all of the above

Q: Your friend says that the helium used to inflate balloons is a product of radioactive decay. Another friend says no way. With whom do you agree? A) If helium were a product of radioactive decay, we would all be radioactive. Agree with the friend that says "no way." B) Radioactive decay produces alpha particles, not helium. Agree with the friend that says "no way." C) Your first friend is correct. Radioactive isotopes emit alpha particles which, in turn, capture electrons and become helium atoms. D) Helium is an element of the periodic table, not some product of any reaction. Agree with the friend that says "no way."

Q: What evidence supports the contention that the strong nuclear force is stronger than the electrical interaction at short inter-nuclear distances? A) Protons are able to exist side-by-side within an atomic nucleus. B) Neutrons spontaneously decay into protons and electrons. C) Uranium deposits are always slightly warmer than their immediate surroundings. D) The radio interference that arises adjacent to any radioactive source.

Q: In bombarding atomic nuclei with proton "bullets," the protons must be accelerated to high energies to make contact with the target nuclei A) because the target nuclei are so small. B) because the target nuclei are negatively charged. C) in order to penetrate through the electrons that surround each target nucleus. D) because the target nuclei are positively charged.

Q: If an atom has 104 electrons, 157 neutrons, and 104 protons, what is its approximate atomic mass? A) The approximate atomic mass is 365. B) The approximate atomic mass is 261. C) The approximate atomic mass is 157. D) The approximate atomic mass is cannot be determined with the information given.

Q: A pair of protons in an atomic nucleus repel each other, but they are also attracted to each other. Why? A) The pair repel each other by nuclear force but attract one another by an electrical force. B) The pair repel each other since they are both positively charges but they are held together by much stronger forces known as quarks. C) The pair attract each other by nuclear force but also repel one another by a weaker electrical force. D) Although it is known that protons repel each other at short distances because of like charge, it is not known what actually holds protons together in the nucleus because we have never seen the nucleus of an atom.

Q: The shell model is an example of a A) physical model. B) conceptual model. C) both a physical and conceptual model. D) None of the above.

Q: According to the shell model, which electrons play the most significant role in determining the properties of an atom? A) those in the innermost shell B) those in the shells between the innermost and outermost shells C) those in the outermost shell D) Electrons in every shell are just about equally important.

Q: According to the shell model, how many shells are required to describe the periodic table? A) one B) seven C) eight D) eighteen

Q: What is the valence shell? A) It is the outermost shell of electrons in an atom. B) It is the shell of electrons in an atom that is the least reactive. C) It is the last partially filled orbital in an atom. D) It is the shell of electrons in element V (atomic no. = 23) E) It is the same as the orbital configuration.

Q: Does a shell have to contain electrons in order to exist? A) A shell is a form of energy that requires electrons in order to exist. B) A shell is just a region of space which may or may not contain electrons. C) A shell is just a conceptual model, hence, it doesn't really exist with or without the electron. D) Two of the above are reasonable answers.

Q: Oxygen, O, (number 8), sulfur, S, (number 16), and selenium, Se, (number 34) have such similar chemical properties because A) their outermost shells contain the same number of electrons. B) because they are all located close to one another in the periodic table. C) they all have the same number of occupied shells. D) These elements can't have similar chemical properties because they are in different periods of the periodic table.

Q: What do the electron configurations for all the group 18 noble gases have in common? A) They have the same number of electrons. B) They occupy the same number of shells. C) Their outermost occupied shells are filled to capacity. D) all of the above

Q: How many electrons are there in the third shell of sodium, Na (atomic number 11)? A) none B) one C) two D) three

Q: How is it possible to deduce the identity of an element from its electron configuration? A) The number of occupied shells corresponds to the atom's atomic number. B) If the atom is electrically neutral, the number of electrons corresponds to the atom's atomic number. C) Using the periodic table, the outermost occupied shell indicates the group while the number of occupied shells indicates the period. D) An electron configuration is unique to each element, much like its atomic spectrum.

Q: The shell model presented in this book is not very accurate. Why then is it presented? A) It reminds us that the study of matter relates to the solar system. B) Most instructors are not good enough artists to duplicate the complicated artwork of true model on the chalk board for explanation purposes. C) The shell model is derived from classical physics, which is still the most widely accepted approach to understanding atomic theory. D) The shell model is simpler and easy to understand.

Q: A practical application of the wave nature of electrons is the A) message chair. B) electron microscope. C) hologram. D) scanning tunneling microscope.

Q: What subatomic particle by itself is least affected by electromagnetic radiation? A) the electron B) the proton C) the neutron D) the nucleus

Q: Some older cars vibrate loudly when driving at particular speeds. For example, at 65 mph the car may be most quiet, but at 60 mph the car rattles uncomfortably. How is this analogous to the quantized energy levels of an electron in an atom? A) A car is designed for maximum performance at particular speeds under given road conditions. Likewise, electron energy level transitions are smooth if they occur while the atom is in a low energy state. Changing the speed of the car for the road conditions is similar to subjecting the atom to unusual energy conditions. B) New cars and small atoms don't share this behavior because modern technology produces better cars and small atoms don't have enough electrons to move among quantized energy levels to cause vibration. C) The vibrating car is analogous to one of the energy levels of the electron, which is the point at which the electron experiences resonance. D) There can be no analogy between a vibrating car and the quantized energy level of an electron in an atom since electrons don't vibrate. Doing so would cause the atom to break apart.

Q: An atom absorbs or emits only particular frequencies of light. White light bends into a glass prism and separates into a rainbow of colors. In which of these two scenarios does the electromagnetic radiation behave as a wave? As a particle? A) Absorption of light shows wave behavior while bending of light shows particle behavior. B) Absorption of light shows particle behavior while bending of light shows wave behavior. C) Both absorption and bending of light show particle behavior. D) Both absorption and bending of light show wave behavior.

Q: In some instances electromagnetic radiation behaves like a wave. In other instances electromagnetic radiation behaves more like a particle. Which behavior more accurately describes the true nature of electromagnetic radiation? A) Particle behavior more accurately describes the true nature of electromagnetic radiation. B) Electromagnetic radiation behaves both as a wave or as a particle depending on the circumstance. C) Wave behavior more accurately describes the true nature of electromagnetic radiation. D) There is no circumstance in which electromagnetic radiation can be described as either portraying particle or wave behavior.

Q: How does the wave model of electrons orbiting the nucleus account for the fact that the electrons can have only discrete energy values? A) Electrons are only able to vibrate at particular frequencies. B) When an electron wave is confined, it is reinforced only at particular frequencies. C) The energy values of an electron only occur where its wave properties and probability clouds are mutually reinforcing. D) The wave model accounts for the types of orbitals an electron may occupy, not it's energy levels.

Q: Which of the following might best explain the reason why electrons are restricted to certain energy levels in an atom? A) They behave like restricted waves and are self-reinforcing. B) They are travelling at very high speeds. C) They are interacting with the light around the atom. D) They are out of phase and self-destruct when outside of distinct energy regions. E) They behave like chaotic waves of alternating frequency.

Q: What property of an electron makes it possible to use electron microscopes? A) They can be focused using smaller lenses. B) They have shorter wavelengths than visible light. C) They are electrically charged. D) They can be generated with electricity. E) none of the above

Q: Which of the following statements about electrons is true? A) Electrons have a negative charge. B) Electrons are particles. C) Electrons behave like waves. D) Electrons in atoms can be excited by light energy. E) all of the above

Q: Which of the following is a property of light? A) It is a wave. B) It is a particle. C) Its energy comes in packets of uniform size. D) all of the above E) none of the above

Q: Light is emitted as an electron transitions from a higher energy state to a lower energy state. How long does it take for the actual transition to take place? A) several seconds B) several microseconds C) several nanoseconds D) no time at all

Q: How might the spectrum of an atom appear if its electrons were not restricted to particular energy levels? A) It would appear nearly the same as it does with the energy level restrictions. B) There would be no frequencies within the visible portion of the electromagnetic spectrum. C) A broad spectrum of all colors would be observed. D) The frequency of the spectral lines would change with temperature.

Q: Which color of light comes from the higher energy transition, red or blue? A) Blue is a higher frequency and therefore corresponds to a lower energy level transition. B) Blue is a higher frequency and therefore corresponds to a higher energy level transition. C) Red is a higher frequency and therefore corresponds to a lower energy level transition. D) Red is a higher frequency and therefore corresponds to a higher energy level transition.

Q: Consider the various frequencies of the three photons emitted from the following three individual electron transitions in the figure below: n=3 to n=2; n=2 to n=1; n=3 to n=1. These transitions would produce three spectral lines in a spectroscope. If the energy spacing between the levels were equal, would this affect the number of spectral lines? A) Yes, two otherwise separate lines would converge into a single more intense line. B) No, but the spacing between the spectral lines would change. C) Yes, two otherwise separate lines would converge into a single less intense line. D) No, but some would then require a prism in order to be seen.

Q: An electron de-excites from the fourth quantum level to the third and then directly to the first. Two frequencies of light are emitted. How do their combined energies compare to the energy of the single frequency that would be emitted by de-excitation from the fourth level directly to the first level?The combined energies of the two frequencies emitted by the one electrons isA) greater than the energy of the single frequency.B) less than the energy of the single frequency.C) equal to the energy of the single frequency.D) not predictable because other factors, such as the temperature of the surroundings must also be considered.

Q: Suppose that a certain atom possesses only four distinct energy levels. Assuming that all transitions between levels are possible, how many spectral lines will this atom exhibit? A) three B) four C) six D) unlimited

Q: How can a hydrogen atom, which has only one electron, have so many spectral lines? A) The electron is able to move at various speeds. B) The protons in the nucleus are also giving off various light frequencies. C) One electron can be boosted to many different energy levels. D) The atomic radius of the hydrogen atom is relatively large.

Q: Which of the following best explains what is happening when an atom emits light? A) An electron is dropping from a higher to a lower energy level with the difference in energy between the two being emitted as light. B) A proton is undergoing a nuclear change in the nucleus and is emitting a high energy light wave in the process. C) An electron is jumping from a low energy state to a high energy state with the difference in energy being converted to light. D) Heat energy is speeding up the orbit of the electrons and the resulting Doppler shift causes light to be emitted from the electrons. E) Heat energy is converting a neutron into a proton and an electron, which is ejected into the orbit of the nucleus, releasing light energy.

Q: Which of the following statements is true about Bohr's planetary model of the atom? A) The electrons actually orbit around the nucleus. B) It is a physical model. C) The energy difference between the orbits is continuous. D) The electrons smoothly move from one orbit to the next. E) none of the above

Q: What is the relationship between the light emitted by an atom and the energies of the electrons in the atom? A) The larger the atom, the greater the number of electrons and therefore the greater the frequency of a light. B) The energies of the electrons of an atom are directly proportional to the wavelength of light emitted and therefore inversely proportional to the frequency of the light emitted. C) The greater the frequency of a photon of light, the greater the energy packed into that photon. D) The light emitted by an atom is a function of its nuclear density and its ability to absorb and reflect various wavelengths of light from the electromagnetic spectrum.

Q: What was Niels Bohr's explanation for the observation of atomic spectra? A) Electrons could only move in discrete energy steps within an atom. B) Electrons could not move in an atom. C) Any photon could excite an electron. D) Only certain photons with the correct energy could excite the quanta in the nucleus. E) Nucleons could be excited by different electron energies.

Q: How is the term photon related to the term quantum? A) A quantum of light is actually one photon. B) A quantum of photons is equal to the wavelength. C) A quantum is a particle of light while a photon is a wave of light. D) A quantum is a particle of light exactly one photon long. E) A quantum is a wave of light while a packet of quanta equals one photon.

Q: What is the main tenet of Plank's quantum hypothesis? A) Energy comes in discrete packets of a certain minimum size. B) Energy is composed of subatomic particles called quanta. C) Energy is a continuum, but light is quantized. D) Energy can be converted into matter through nuclear quanta. E) Light is composed of waves that exist only at certain quantum fundamental frequencies.

Q: Which of the following is most easily understood to be quantized? A) the number of eggs in an egg carton B) the amount of water in a glass C) the volume of air in a balloon D) the amount of time in an hour E) none of the above

Q: When a rainbow of colors of light are combined into a single ray it forms A) white. B) black. C) an intense rainbow of colors. D) It's not possible to combine colors once separated.

Q: The color of a firework comes from the glowing of A) molecules. B) atoms. C) gun powder. D) laser light.

Q: How might you distinguish a sodium-vapor street lamp from a mercury-vapor street lamp? A) Use binoculars to look for printing adjacent to the bulb. B) Look at the street lamps through a spectroscope and match their spectral patterns to their respective atomic spectra. C) Ask your local utility company to identify these lamps for you. D) The shadows cast from a sodium-vapor street lamp tend to be more diffuse around the edges.

Q: How would you describe light generated by heating pure elements if it was observed through a prism or spectroscope? A) You would see a series of very sharp lines of emitted light. B) You would see a rainbow of colors. C) Light is absorbed by heated elements so you would not see anything. D) You would see one line of emitted light, but it would be different for each element. E) none of the above

Q: The ________ represents the complete range of frequencies of light energy from radio waves to cosmic rays. A) electromagnetic spectrum B) electron configuration C) probability cloud D) frequency dependence E) spectroscopic model

Q: If a baseball were scaled up to the size of planet Earth, each of its atoms would be about the size of A) a baseball stadium. B) a flea. C) an atom. D) a ping-pong ball.