Certainly! Elements with a lower electron configuration than their atomic number typically occur when electrons occupy higher energy levels or subshells, leaving lower energy levels or subshells incompletely filled. Here are a few examples:
Chromium (Cr) - Atomic Number: 24 Electron Configuration: [Ar] 3d⁵ 4s¹ Chromium has a lower electron configuration than its atomic number because it has one electron in the 4s orbital and five electrons in the 3d orbital, rather than filling the 4s² configuration first. This arrangement provides more stability due to half-filled or fully-filled subshells.
Copper (Cu) - Atomic Number: 29 Electron Configuration: [Ar] 3d¹⁰ 4s¹ Copper has a lower electron configuration than its atomic number because it has one electron in the 4s orbital and ten electrons in the 3d orbital, instead of filling the 4s² configuration first. Again, this arrangement is more stable due to a half-filled or fully-filled 3d subshell.
Silver (Ag) - Atomic Number: 47 Electron Configuration: [Kr] 4d¹⁰ 5s¹ Silver has a lower electron configuration than its atomic number because it has one electron in the 5s orbital and ten electrons in the 4d orbital, rather than filling the 5s² configuration first. This configuration provides more stability due to a half-filled or fully-filled 4d subshell.
Gold (Au) - Atomic Number: 79 Electron Configuration: [Xe] 4f¹⁴ 5d¹⁰ 6s¹ Gold has a lower electron configuration than its atomic number because it has one electron in the 6s orbital, ten electrons in the 5d orbital, and fourteen electrons in the 4f orbital, rather than filling the 6s² and 5d¹⁰ configurations first. Again, this arrangement offers more stability due to half-filled or fully-filled subshells.
These examples illustrate cases where electrons occupy higher energy levels or subshells to achieve greater stability through half-filled or fully-filled subshells, deviating from the expected electron configuration based solely on the atomic number.