Ch.2 - Atoms, Molecules & Ions
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- At room temperature, a certain element is found to be a shiny, silver-colored solid that is a poor conductor of electricity. When a sample of the element is hit with a hammer, it shatters. Is the element likely to be a metal, a nonmetal, or a semimetal?
Problem 69
- At room temperature, a certain element is yellow crystalline solid. It does not conduct electricity and when hit with a hammer, it shatters. Is the element likely to be a metal, a nonmetal, or a semimetal?
Problem 70
- At room temperature, a certain element is a colorless, unre-active gas. Is the element likely to be a metal, a nonmetal, or a semimetal?
Problem 71
- In which of the periodic groups 1A, 2A, 5A, and 7A is the first letter of all elements' symbol the same as the first letter of their name?
Problem 72
- For which elements in groups 1A, 2A, 5A, and 7A of the periodic table does the first letter of their symbol differ from the first letter of their name?
Problem 73
Problem 74
Which type of property—intensive or extensive—does not depend on the amount of substance present?
- How does Dalton's atomic theory account for the law of mass conservation and the law of definite proportions?
Problem 76
- What is the law of multiple proportions, and how does Dalton's atomic theory account for it?
Problem 77
- A sample of mercury with a mass of 114.0 g was combined with 12.8 g of oxygen gas, and the resulting reaction gave 123.1 g of mercury(II) oxide. How much oxygen was left over after the reaction was complete?
Problem 78
- A sample of CaCO3 was heated, causing it to form CaO and CO2 gas. Solid CaO remained behind, while the CO2 escaped to the atmosphere. If the CaCO3 weighed 612 g and the CaO weighed 343 g, how many grams of CO2 were formed in the reaction?
Problem 79
- In methane, one part hydrogen combines with three parts carbon by mass. If a sample of a compound containing only carbon and hydrogen contains 32.0 g of carbon and 8.0 g of hydrogen, could the sample be methane? If the sample is not methane, show that the law of multiple proportions is fol-lowed for methane and this other substance.
Problem 80
- In borane, one part hydrogen combines with 3.6 parts boron by mass. A compound containing only hydrogen and boron contains 6.0 g of hydrogen and 43.2 g of boron. Could this compound be borane? If it is not borane, show that the law of multiple proportions is followed for borane and this other substance.
Problem 81
- Benzene, ethane, and ethylene are just three of a large num-ber of hydrocarbons—compounds that contain only carbon and hydrogen. Show how the following data are consistent with the law of multiple proportions.
Problem 82
- The atomic weight of carbon (12.011) is approximately 12 times that of hydrogen (1.008). (a) Show how you can use this knowledge to calculate pos-sible formulas for benzene, ethane, and ethylene (Prob-lem 2.82).
Problem 83
- Two compounds containing carbon and oxygen have the following percent composition by mass. Compound 1: 42.9% carbon and 57.1% oxygen Compound 2: 27.3% carbon and 72.7% oxygen Show that the law of multiple proportions is followed. If the formula of the first compound is CO, what is the formula of the second compound?
Problem 84
- In addition to carbon monoxide (CO) and carbon dioxide (CO2), there is a third compound of carbon and oxygen called carbon suboxide. If a 2.500 g sample of carbon suboxide contains 1.32 g of C and 1.18 g of O, show that the law of multiple proportions is followed. What is a possible formula for carbon suboxide?
Problem 85
- The results from Thomson’s cathode-ray tube experiment led to the discovery of which subatomic particle?
Problem 86
- What affects the magnitude of the deflection of the cathode ray in Thomson's experiment?
Problem 87
Problem 88b
Label the following statements about J. J. Thomson's cathode-ray tube experiments shown in Figure 2.6 as true or false. (b) A cathode ray is a stream of charged particles.
Problem 88c
Label the following statements about J. J. Thomson's cathode-ray tube experiments shown in Figure 2.6 as true or false. (c) The cathode ray is deflected away from a positively charged plate.
Problem 88f
Label the following statements about J. J. Thomson's cathode-ray tube experiments shown in Figure 2.6 as true or false. (f) By measuring the deflection of the cathode ray beam caused by electric fields of known strength, the charge-to-mass ratio of the electron was calculated.
- Which of the following charges is not possible for the over-all charge on an oil droplet in Millikan's experiment? For this problem, we'll round the currently accepted charge of an electron to 1.602 * 10-19 C. (a) -1.010 * 10-18 C (b) -8.010 * 10-19 C (c) -2.403 * 10-18 C
Problem 90
- What discovery about atomic structure was made from the results of Rutherford's gold foil experiment?
Problem 91
- Prior to Rutherford's gold foil experi-ment, the 'plum pudding' model of the atom represented atomic structure. In this model, the atom is composed of elec-trons interspersed within a positive cloud of charge. If this were the correct model of the atom, predict how the results of Rutherford's experiment would have been different. (a) The alpha particles would pass right through the gold foil with little to no deflection. (b) Most of the alpha particles would be deflected back toward the source. (c) Most of the alpha particles would be absorbed by the atom and neither pass through nor be deflected from the gold foil.
Problem 92
Problem 93
A period at the end of sentence written with a graphite pencil has a diameter of 1 mm. If the period represented the nucleus, approximately how large is the diameter of the entire atom in units of m?
Problem 95
A period at the end of sentence written with a graphite pen-cil has a diameter of 1 mm. How many carbon atoms would it take to line up across the period if a single carbon atom has a diameter of 150 pm?
- What is the difference between an atom's atomic number and its mass number?
Problem 96
- What is the difference between an element's atomic number and its atomic weight?
Problem 97
- The subscript giving the atomic number of an atom is often left off when writing an isotope symbol. For example, 6 often written simply as 13C. Why is this allowed?
Problem 98
- Iodine has a lower atomic mass than tellurium (126.90 for iodine, 127.60 for tellurium) even though it has a higher atomic number (53 for iodine, 52 for tellurium). Explain.
Problem 99