Problem 47
One of the most widely used isotopes in medical diagnostics is technetium- \(99 \mathrm{~m}\) (the \(m\) indicates that it is a metastable isotope). Write the symbol for this isotope, indicating both mass number and atomic number.
Problem 48
Naturally occurring copper is a mixture of \(69.17 \%\) Cu-63 with a mass of 62.93 amu and \(30.83 \%\) Cu-65 with a mass of 64.93 amu. What is the atomic mass of copper?
Problem 49
Naturally occurring lithium is a mixture of \(92.58 \% \mathrm{Li}-7\) with a mass of 7.016 amu and \(7.42 \%\) Li-6 with a mass of 6.015 amu. What is the atomic mass of lithium?
Problem 51
Why does the fourth period in the periodic table contain 18 elements?
Problem 52
Americium, atomic number \(95,\) is used in household smoke detectors. What is the symbol for americium? Is americium a metal, a nonmetal, or a metalloid?
Problem 53
What subshell is being filled for the metalloid elements?
Problem 54
Answer the following questions for the elements from scandium through zinc: (a) Are they metals or nonmetals? (b) To what general class of elements do they belong? (c) What subshell is being filled by electrons in these elements?
Problem 55
Answer the following questions for the elements from cerium through lutetium: (a) Are they metals or nonmetals? (b) To what general class of elements do they belong? (c) What subshell is being filled by electrons in these elements?
Problem 56
For (a) rubidium (b) tungsten, (c) germanium, and (d) krypton, which of the following terms apply? (i) metal, (ii) nonmetal, (iii) metalloid (iv) transition element, (v) main group element, (vi) noble gas, (vii) alkali metal, (viii) alkaline earth metal.
Problem 57
For (a) calcium, (b) palladium, (c) carbon, and (d) radon, which of the following terms apply? (i) metal, (ii) nonmetal, (iii) metalloid, (iv) transition element, (v) main group element. (vi) noble gas, (vii) alkali metal, (viii) alkaline earth metal.
