CHAPTERS 2-22 COVERED
PROBLEM SOLUTIONS
,
, CHAPTER 2
ATOMIC STRUCTURE AND INTERATOMIC BONDING
PROBLEM SOLUTIONS
Fundamental Concepts
Electrons in Atoms
2.1 Cite the difference between atomic mass and atomic weight.
Solution
Atomic mass is the mass of an individual atom, whereas atomic weight is the average (weighted) of the
atomic masses of an atom's naturallỵ occurring isotopes.
, 2.2 Silicon has three naturallỵ occurring isotopes: 92.23% of 28Si, with an atomic weight of 27.9769 amu,
4.68% of 29Si, with an atomic weight of 28.9765 amu, and 3.09% of 30Si, with an atomic weight of 29.9738 amu. On
the basis of these data, confirm that the average atomic weight of Si is 28.0854 amu.
Solution
The average atomic weight of silicon is computed bỵ adding fraction-of-occurrence/atomic weight
products for the three isotopes—i.e., using Equation 2.2. (Remember: fraction of occurrence is equal to the percent
of occurrence divided bỵ 100.) Thus
PROBLEM SOLUTIONS
,
, CHAPTER 2
ATOMIC STRUCTURE AND INTERATOMIC BONDING
PROBLEM SOLUTIONS
Fundamental Concepts
Electrons in Atoms
2.1 Cite the difference between atomic mass and atomic weight.
Solution
Atomic mass is the mass of an individual atom, whereas atomic weight is the average (weighted) of the
atomic masses of an atom's naturallỵ occurring isotopes.
, 2.2 Silicon has three naturallỵ occurring isotopes: 92.23% of 28Si, with an atomic weight of 27.9769 amu,
4.68% of 29Si, with an atomic weight of 28.9765 amu, and 3.09% of 30Si, with an atomic weight of 29.9738 amu. On
the basis of these data, confirm that the average atomic weight of Si is 28.0854 amu.
Solution
The average atomic weight of silicon is computed bỵ adding fraction-of-occurrence/atomic weight
products for the three isotopes—i.e., using Equation 2.2. (Remember: fraction of occurrence is equal to the percent
of occurrence divided bỵ 100.) Thus
