Problem 30
Which of Dalton's postulates about atoms are inconsistent with later observations? Do these inconsistencies mean that Dalton was wrong? Is Dalton's model still useful? Explain.
Problem 31
Use Dalton's theory to explain why potassium nitrate from India or Italy has the same mass percents of \(\mathrm{K}, \mathrm{N},\) and \(\mathrm{O}\).
Problem 32
Thomson was able to determine the mass/charge ratio of the electron but not its mass. How did Millikan's experiment allow determination of the electron's mass?
Problem 34
Describe Thomson's model of the atom. How might it account for the production of cathode rays?
Problem 35
When Rutherford's coworkers bombarded gold foil with \(\alpha\) particles, they obtained results that overturned the existing (Thomson) model of the atom. Explain.
Problem 37
Choose the correct answer. The difference between the mass number of an isotope and its atomic number is (a) directly related to the identity of the element; (b) the number of electrons; (c) the number of neutrons; (d) the number of isotopes.
Problem 39
Chlorine has two naturally occurring isotopes, \({ }^{35} \mathrm{Cl}\) (abundance \(76 \%\) ) and \({ }^{37} \mathrm{Cl}\) (abundance \(24 \%\) ), and it occurs as diatomic (two-atom) molecules. In a mass spectrum, peaks are seen for the molecule and for the separated atoms. (a) How many peaks are in the mass spectrum? (b) What is the \(m / e\) value for the heaviest particle and for the lightest particle?
Problem 40
Argon has three naturally occurring isotopes, \({ }^{36} \mathrm{Ar},{ }^{38} \mathrm{Ar}\) and \({ }^{40}\) Ar. What is the mass number of each isotope? How many protons, neutrons, and electrons are present in each?
Problem 42
Do both members of the following pairs have the same number of protons? Neutrons? Electrons? (a) \({ }_{8}^{16} \mathrm{O}\) and \({ }_{8}^{17} \mathrm{O}\) (b) \({ }_{18}^{40} \mathrm{Ar}\) and \({ }_{19}^{41} \mathrm{~K}\) (c) \({ }_{27}^{60} \mathrm{Co}\) and \({ }_{28}^{60} \mathrm{Ni}\)
Problem 43
Do both members of the following pairs have the same number of protons? Neutrons? Electrons? (a) \({ }_{1}^{2} \mathrm{H}\) and \({ }_{2}^{2} \mathrm{He}\) (b) \({ }_{6}^{14} \mathrm{C}\) and \({ }_{7}^{15} \mathrm{~N}\) (c) \({ }^{10} \mathrm{~F}\) and \({ }_{9}^{18} \mathrm{~F}\) Which pair(s) consist(s) of atoms with the same \(Z\) value? \(N\) value? \(A\) value?
