Chapter 4 - The Structure of Atoms - Exercises - Atomic Composition, Isotopes, and Atomic Weights - Page 164: 17

$Si^{28}$ contains 14 neutrons, 14 protons, and 14 electrons $Si^{29}$ contains 15 neutrons, 14 protons, and 14 electrons $Si^{30}$ contains 16 neutrons, 14 protons, and 14 electrons

Si has 14 atomic numbers which mean that all Si isotopes will have 14 protons and 14 electrons $Si^{28}$ isotope has 28 mass number Since mass number=number of protons+number of neutrons So, Number of neutrons=massnumber-number of protons=28-14=14 neutrons $Si^{28}$ contains 14 neutrons, 14 protons, and 14 electrons $Si^{29}$ isotope has 29 mass number Since mass number=number of protons+number of neutrons So, Number of neutrons=massnumber-number of protons=29-14=15 neutrons $Si^{29}$ contains 15 neutrons, 14 protons, and 14 electrons $Si^{30}$ isotope has 30 mass number Since mass number=number of protons+number of neutrons So, Number of neutrons=massnumber-number of protons=30-14=16 neutrons $Si^{30}$ contains 16 neutrons, 14 protons, and 14 electrons