Answer
a. $^{16}_8O$
b. $^{19}_9F$
c. $^{23}_{11}Na$
d. $^{27}_{13}Al$
Work Step by Step
1. Calculate the mass number for each isotope:
a. A = 8 + 8 = 16
b. A = 9 + 10 = 19
c. A = 11 + 12 = 23
d. A = 13 + 14 = 27
2. Write the isotopic symbol, using the mass number as a superscript, and the atomic number as a subscript.
a. $^{16}_8O$
b. $^{19}_9F$
c. $^{23}_{11}Na$
d. $^{27}_{13}Al$
** Consult Figure 4.9, page 102, to see the symbols and atomic numbers for each of these elements.