Concept explainers
In each pair of isotopes shown, indicate which one you would expect to be radioactive: (a)
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Chemistry
- 2.10 Which isotope in each pair contains more neutrons? (A) 35Cl or 33S, (b) 19F or 19Ne, (c) 63Cu or 65Zn, (d) 126I or 127Tearrow_forwardDefine the term atomic weight. Why might the values of atomic weights on a planet elsewhere in the universe be different from those on earth?arrow_forwardThough the common isotope of aluminum has a mass number of 27, isotopes of aluminum have been isolated (or prepared in nuclear reactors) with mass numbers of 24, 25, 26, 28, 29, and 30. How many neutrons are present in each of these isotopes? Why are they all considered aluminum atoms, even though they differ greatly in mass? Write the atomic symbol for each isotope.arrow_forward
- Cerium is the most abundant rare earth metal. Pure cerium ignites when scratched by even a soft object. It has four known isotopes: 136Ce(atomicmass=135.907amu) ,138Ce(atomicmass=137.905amu) ,140Ce(atomicmass=139.905amu), and142Ce(atomicmass=141.909amu). Ce-140 and Ce-142 are fairly abundant. Which is the more abundant isotope?arrow_forwardDuring nuclear decay a 238U atom can break apart into a helium-4 atom and one other atom. Assuming that no subatomic particles are destroyed during this decay process, what is the other element produced?arrow_forwardWhile traveling to a distant universe, you discover the hypothetical element X. You obtain a representative sample of the element and discover that it is made up of two isotopes, X-23 and X-25. To help your science team calculate the atomic weight of the substance, you send the following drawing of your sample with your report. In the report, you also inform the science team that the brown atoms are X-23, which have an isotopic mass of 23.02 amu, and the green atoms are X-25, which have an isotopic mass of 25.147 amu. What is the atomic weight of element X?arrow_forward
- 2.86 For some uses, the relative abundance of isotopes must be manipulated. For example, a medical technique called boron neutron capture therapy needs a higher fraction of 10B than occurs naturally to achieve its best efficiency. What would happen to the atomic weight of a sample of boron that had been enriched in 10B? Explain your answer in terms of the concept of a weighted average.arrow_forwardSee the definition for isobars in Question 15. Consider Cr-54, Fe-54, Fess, and Ni-S8. (a) Which of these are isobars? Which are isotopes? (b) What do Fe-S4 and Fe-58 have in common? (c) Which atoms have the same number of neutrons?arrow_forwardFill in the following table:arrow_forward
- 2.90 Naturally occurring europium has an average atomic weight of 151.964 amu. If the only isotopes of europium present are 151Eu and 153Eu, describe how you would determine the relative abundance of the two isotopes. Include in your description any information that would need to be looked up.arrow_forwardBromine has two occuring isotopes: 79Br with atomic mass 78.9183 and 81Br with atomic mass 80.9163. Without using a calculator, what would you estimate the % abundance of Br-79 to be?arrow_forwardNeon is an inert gas with three stable isotopes. It is used in gas lasers and in advertising signs. Its isotopes and their abundances are: Ne-20 19.9924 amu 90.51% Ne-21 20.9938 amu 0.27% Ne-22 21.9914 amu 9.22% What is the average atomic mass of neon?arrow_forward
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