Write the electron configurations for the following ions, and determine which have noble-gas configurations: (a) \(\mathrm{Cu}^{2+}\) (b) \(\mathrm{Ca}^{2+},(\mathbf{c}) \mathrm{N}^{3-}\) (d) \(\mathrm{Ru}^{2+}\), (e) \(\mathrm{H}^{-}\).

To write electron configurations, we need to find the atomic number of each element mentioned. Atomic numbers correspond to the number of protons in their nucleus, which also determines the number of electrons in the neutral atom. Here are the atomic numbers for the elements in question: Cu: 29 Ca: 20 N: 7 Ru: 44 H: 1 Next, we will use these atomic numbers to determine the electron configurations for each ion.

To write electron configurations for these ions, we first need to know the number of electrons in each ion. We can determine this by referring to the atomic numbers and adding or subtracting the charge of each ion. (a) \(\mathrm{Cu}^{2+}\): 29 - 2 = 27 electrons (b) \(\mathrm{Ca}^{2+}\): 20 - 2 = 18 electrons (c) \(\mathrm{N}^{3-}\): 7 + 3 = 10 electrons (d) \(\mathrm{Ru}^{2+}\): 44 - 2 = 42 electrons (e) \(\mathrm{H}^{-}\): 1 + 1 = 2 electrons Now we can write electron configurations for each ion: (a) \(\mathrm{Cu}^{2+}\): [Ar] \(3d^9\) (b) \(\mathrm{Ca}^{2+}\): [Ar] (c) \(\mathrm{N}^{3-}\): [He] \(2s^2 2p^6\) (d) \(\mathrm{Ru}^{2+}\): [Kr] \(4d^6\) (e) \(\mathrm{H}^{-}\): \(1s^2\)

We can now compare the electron configurations of each ion to the noble gases in order to determine which ions have noble-gas configurations. The noble gases are Helium (He), Neon (Ne), Argon (Ar), Krypton (Kr), Xenon (Xe), and Radon (Rn), and they possess completely filled electron shells. (a) \(\mathrm{Cu}^{2+}\): [Ar] \(3d^9\) - Not a noble-gas configuration (b) \(\mathrm{Ca}^{2+}\): [Ar] - Noble-gas configuration (Argon) (c) \(\mathrm{N}^{3-}\): [He] \(2s^2 2p^6\) - Noble-gas configuration (Neon) (d) \(\mathrm{Ru}^{2+}\): [Kr] \(4d^6\) - Not a noble-gas configuration (e) \(\mathrm{H}^{-}\): \(1s^2\) - Noble-gas configuration (Helium) The ions \(\mathrm{Ca}^{2+}\), \(\mathrm{N}^{3-}\), and \(\mathrm{H}^{-}\) have noble-gas configurations.