Selenium has an atomic number of 34 and a mass number of 79.
1. What are the number of protons, neutrons, and electrons in a selenide ion with a -2 charge?
To determine the number of protons, neutrons, and electrons in a selenide ion with a -2 charge, we need to consider the atomic number and the charge.
1. Number of Protons (P): The atomic number of selenium is 34. Since the number of protons in an atom equals the atomic number, a selenium atom has 34 protons.
2. Number of Electrons (E): To determine the number of electrons in a selenide ion with a -2 charge, we subtract the charge from the number of protons. Since a -2 charge implies two extra electrons, the selenide ion would have 34 protons + 2 extra electrons = 36 electrons.
3. Number of Neutrons (N): To calculate the number of neutrons, we subtract the atomic number from the mass number. Given that the mass number of selenium is 79, the number of neutrons can be calculated as 79 - 34 = 45 neutrons.
Therefore, a selenide ion with a -2 charge would have:
- 34 protons
- 45 neutrons
- 36 electrons