Problem 38
Group the following elements in pairs that you would expect to show similar chemical properties: \(\mathrm{I}, \mathrm{Ba}, \mathrm{O}, \mathrm{Br}\), \(\mathrm{S}\) and \(\mathrm{Ca}\)
Problem 39
Write the symbol for each of the following biologically important elements in the given periodie table: iron (present in hemoglobin for transporting oxygen), iodine (present in the thyroid gland), sodium (present in intracellular and extracellular fluids), phosphorus (present in bones and teeth), sulfur (present in proteins). and magnesium (present in chlorophyll molecules).
Problem 40
What is an atomic mass unit? Why is it necessary to introduce such a unit?
Problem 41
What is the mass (in amu) of a carbon- 12 atom? Why is the atomic mass of earbon listed as 12.01 amu in the table on the inside front cover of this book?
Problem 42
Explain clearly what is meant by the statement"The atomic mass of gold is 197.0 amu."
Problem 43
What information would you need to calculate the average atomic mass of an element?
Problem 44
The atomic masses of \({ }_{15}^{74} \mathrm{Br}\left(50.69\right.\) percent) and \({ }_{35}^{81} \mathrm{Br}\) (49.31 percent) are 78.9183361 and 80.916289 amu, respectively. Calculate the average atomic mass of bromine. The percentages in parentheses denote the relative abundances.
Problem 45
The atomic masses of \({ }^{204} \mathrm{~Pb}\left(1.4\right.\) percent), \({ }^{, 06} \mathrm{P} \mathrm{b}\) (24.1 percent), \({ }^{207} \mathrm{~Pb}\) ( 22.1 percent), and \({ }^{20 \mathrm{c} \mathrm{s}} \mathrm{Pb}\) \((52.4\) percent) are \(203.973020 .205 .974440,206.975872,\) and 207.976627 amu, respectively. Calculate the average atomic mass of lead. The percentages in parentheses denote the relative abundances.
Problem 47
The atomic masses of \({ }^{6} \mathrm{Li}\) and \({ }^{7} \mathrm{~L}_{\mathrm{i}}\) are \(6.0151 \mathrm{amu}\) and 7.0160 amu, respectively. Calculate the natural abundances of these two isotopes. The average atomic mass of \(\mathrm{Li}\) is 6.941 amu.
Problem 48
What is the mass in grams of 13.2 amu?
