Question 2.4: Determining the Numbers of Subatomic Particles in the Isotop......

Plan The mass number (A; left superscript) of each of the three isotopes is given, which is the sum of protons and neutrons. From the List of Elements on the text’s inside front cover (Table 1), we find the atomic number (Z, number of protons), which equals the number of electrons. We obtain the number of neutrons by subtracting Z from A (Equation 2.2).

Solution From the elements list (Table 1), the atomic number of silicon is 14. Therefore,

                  ^{28}\text{Si has 14p}^+\text{, 14e}^−\text{, and 14n}^0\text{(28 − 14)}
                  ^{29}\text{Si has 14p}^+\text{, 14e}^−\text{, and 15n}^0\text{(29 − 14)}
                  ^{30}\text{Si has 14p}^+\text{, 14e}^−\text{, and 16n}^0\text{(30 − 14)}