Fine: Chapter 5, Problem 33

Problem   On page 218: Write down the electronic configuration for each of the following:

1. A ground-state arsenic atom (Z = 33)
2. A ground-state titanium atom (Z = 22)
3. A ground-state iodine atom (Z = 53)

Solution   We could actually just look at table 5.7 on page 205, look up Z and write down what we find, as the three atoms are in their ground state. Doing this gives us:

1. The arsenic atom has a ground-state [Ar]4s²3d¹⁰4p³ configuration. To be complete, we should also specify that [Ar] = [Ne]3s²3p⁶ = [He]2s²2p⁶   3s²3p⁶ = 1s²   2s²2p⁶   3s²3p⁶. Then, the arsenic atom, As has the electronic configuration: 1s²   2s²2p⁶   3s²3p⁶   4s²3d¹⁰4p³.
2. The titanium atom has a ground-state [Ar]4s²3d² configuration. To be complete, we should also specify that [Ar] = 1s²   2s²2p⁶   3s²3p⁶ to arrive at the configuration: 1s²   2s²2p⁶   3s²3p⁶   4s²3d².
3. The iodine atom has ground-state configuration [Kr]5s²4d¹⁰5p⁵. With [Kr] = [Ar]4s²3d¹⁰4p⁶ = 1s²   2s²2p⁶   3s²3p⁶   4s²3d¹⁰4p⁶, we eventually arrive at the electronic configuration: 1s²   2s²2p⁶   3s²3p⁶   4s²3d¹⁰4p⁶   5s²4d¹⁰5p⁵.