In the space below, write the unabbreviated electron configurations of the following elements:
sodium
iron
bromine
barium
neptunium
The Correct Answer and Explanation is:
Certainly! Here are the unabbreviated electron configurations for the given elements:
1. Sodium (Na), atomic number 11
Electron configuration:
1s² 2s² 2p⁶ 3s¹
2. Iron (Fe), atomic number 26
Electron configuration:
1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d⁶
3. Bromine (Br), atomic number 35
Electron configuration:
1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁵
4. Barium (Ba), atomic number 56
Electron configuration:
1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s²
5. Neptunium (Np), atomic number 93
Electron configuration:
1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴ 5d¹⁰ 6p⁶ 7s² 5f⁴
Explanation (300+ words):
Electron configuration describes the distribution of electrons in an atom’s orbitals. Each electron occupies an orbital according to the Pauli exclusion principle, Hund’s rule, and the Aufbau principle. The order of filling orbitals generally follows the increasing energy levels, starting from 1s, then 2s, 2p, 3s, 3p, 4s, and so forth.
Sodium (Na) has 11 electrons. After filling the 1s, 2s, and 2p orbitals (which accommodate 2, 2, and 6 electrons respectively), the 11th electron goes into the 3s orbital, making the configuration 1s² 2s² 2p⁶ 3s¹.
Iron (Fe) has 26 electrons. The first 18 electrons fill the orbitals up to 3p⁶, then 4s fills before 3d. Although the 3d orbital is in the 3rd shell, it fills after 4s due to energy considerations. So, after filling 4s², the next 6 electrons go into 3d orbitals, giving 4s² 3d⁶.
Bromine (Br) has 35 electrons. After completing up to 3p⁶, electrons fill 4s², then 3d¹⁰, and finally 4p orbitals. Bromine is one electron short of a full 4p shell, so its configuration ends at 4p⁵.
Barium (Ba), a heavier element with 56 electrons, fills up orbitals in sequence through multiple shells, including the 4d¹⁰ and 5p⁶ orbitals, reaching 6s² as its valence shell electrons. The configuration reflects the filling of lower energy shells first, before reaching higher energy levels.
Neptunium (Np) is an actinide with atomic number 93. Its electron configuration includes filling 5f orbitals after the 7s orbital. The actinides involve the filling of 5f orbitals, which is why after the 7s² electrons, 5f electrons start to fill, here 5f⁴ for neptunium.
Understanding electron configurations is crucial for explaining chemical behavior, bonding, magnetism, and periodic trends of elements. The orbital filling order is not always intuitive, especially with transition metals and inner transition metals (lanthanides and actinides), due to similar energy levels of orbitals and electron-electron interactions affecting stability.
If you want, I can also provide explanations on how the configurations relate to chemical properties or periodic trends
