Question

electron configuration practice worksheet
in the space below, write the unabbreviated electron configurations of the following elements:

1. sodium
2. iron
3. bromine
4. barium
5. neptunium

Explanation:

Step1: Determine the atomic number

• Sodium (\(Na\)) has an atomic number of \(11\).
• Iron (\(Fe\)) has an atomic number of \(26\).
• Bromine (\(Br\)) has an atomic number of \(35\).
• Barium (\(Ba\)) has an atomic number of \(56\).
• Neptunium (\(Np\)) has an atomic number of \(93\).

Step2: Write the electron configuration using Aufbau principle

• For sodium (\(Z = 11\)):
• Fill orbitals in the order \(1s<2s<2p<3s\).
• \(1s^{2}2s^{2}2p^{6}3s^{1}\)
• For iron (\(Z = 26\)):
• Fill orbitals in the order \(1s<2s<2p<3s<3p<4s<3d\).
• \(1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^{6}\)
• For bromine (\(Z = 35\)):
• Fill orbitals in the order \(1s<2s<2p<3s<3p<4s<3d<4p\).
• \(1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^{10}4p^{5}\)
• For barium (\(Z = 56\)):
• Fill orbitals in the order \(1s<2s<2p<3s<3p<4s<3d<4p<5s<4d<5p<6s\).
• \(1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^{10}4p^{6}5s^{2}4d^{10}5p^{6}6s^{2}\)
• For neptunium (\(Z = 93\)):
• Fill orbitals in the order \(1s<2s<2p<3s<3p<4s<3d<4p<5s<4d<5p<6s<4f<5d<6p<7s<5f<6d\).
• \(1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^{10}4p^{6}5s^{2}4d^{10}5p^{6}6s^{2}4f^{14}5d^{10}6p^{6}7s^{2}5f^{4}6d^{1}\)

Answer:

1. \(1s^{2}2s^{2}2p^{6}3s^{1}\)
2. \(1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^{6}\)
3. \(1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^{10}4p^{5}\)
4. \(1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^{10}4p^{6}5s^{2}4d^{10}5p^{6}6s^{2}\)
5. \(1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^{10}4p^{6}5s^{2}4d^{10}5p^{6}6s^{2}4f^{14}5d^{10}6p^{6}7s^{2}5f^{4}6d^{1}\)