Concept explainers
Copper is composed of two naturally occurring isotopes:
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Chapter 3 Solutions
Chemistry In Focus
- Average atomic masses listed by JUPAC are based on a study of experimental results. Bromine has two isotopes 79Br and 81Br, whose masses (78.9 183 and 80.9 163 amu) and abundances (50.69% and 49.3 1%) were determined in earlier experiments. Calculate the average atomic mass of bromine based on these experiments.arrow_forwardUranium-235 is the isotope of uranium commonly used in nuclear power plants. How many (a) protons are in its nucleus? (b) neutrons are in its nucleus? (c) electrons are in a uranium atom?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_forward
- The element europium exists in nature as two isotopes: 151Eu has a mass of 150.9196 u and 153Eu has a mass of 152.9209 u. The average atomic mass of europium is 151.96 u. Calculate the relative abundance of the two europium isotopes.arrow_forwardChlorine has two natural isotopes: 1737Cl and 1735Cl. Hydrogen reacts with chlorine to form the compound HCl. Would a given amount of hydrogen react with different masses of the two chlorine isotopes? Does this conflict with the law of definite proportion? Why or why not?arrow_forwardAn element consists of 1.40% of an isotope with mass 203.973 u, 24.10% of an isotope with mass 205.9745 u, 22.10% of an isotope with mass 206.9759 u, and 52.40% of an isotope with mass 207.Y766 u. Calculate the average atomic mass, and identify the element.arrow_forward
- Average Atomic Weight Part 1: Consider the four identical spheres below, each with a mass of 2.00 g. Calculate the average mass of a sphere in this sample. Part 2: Now consider a sample that consists of four spheres, each with a different mass: blue mass is 2.00 g, red mass is 1.75 g, green mass is 3.00 g, and yellow mass is 1.25 g. a Calculate the average mass of a sphere in this sample. b How does the average mass for a sphere in this sample compare with the average mass of the sample that consisted just of the blue spheres? How can such different samples have their averages turn out the way they did? Part 3: Consider two jars. One jar contains 100 blue spheres, and the other jar contains 25 each of red, blue, green, and yellow colors mixed together. a If you were to remove 50 blue spheres from the jar containing just the blue spheres, what would be the total mass of spheres left in the jar? (Note that the masses of the spheres are given in Part 2.) b If you were to remove 50 spheres from the jar containing the mixture (assume you get a representative distribution of colors), what would be the total mass of spheres left in the jar? c In the case of the mixture of spheres, does the average mass of the spheres necessarily represent the mass of an individual sphere in the sample? d If you had 80.0 grams of spheres from the blue sample, how many spheres would you have? e If you had 60.0 grams of spheres from the mixed-color sample, how many spheres would you have? What assumption did you make about your sample when performing this calculation? Part 4: Consider a sample that consists of three green spheres and one blue sphere. The green mass is 3.00 g, and the blue mass is 1.00 g. a Calculate the fractional abundance of each sphere in the sample. b Use the fractional abundance to calculate the average mass of the spheres in this sample. c How are the ideas developed in this Concept Exploration related to the atomic weights of the elements?arrow_forwardScientists J. J. Thomson and William Thomson (Lord Kelvin) made numerous contributions to our understanding of the atom’s structure. Which subatomic particle did J. J. Thomson discover, and what did this lead him to postulate about the nature of the atom? William Thomson postulated what became known as the “plum pudding” model of the atom’s structure. What did this model suggest?arrow_forwardThe average atomic masses of some elements may vary, depending upon the sources of their ores. Naturally occurring boron consists of two isotopes with accurately known masses ( 10B, 10.0129 amu and 11B, 11.0931 amu). The actual atomic mass of boron can vary from 10.807 to 10.8 19, depending on whether the mineral source is from Turkey or the United States. Calculate the percent abundances leading to the two values of the average atomic masses of boron from these two countries.arrow_forward
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