Question

1. write the noble gas configuration for:

a. lithium:
b. argon:
c. iron:
d. barium:

Explanation:

Step1: Determine the atomic number

• Lithium (\(Li\)) has an atomic number of \(3\). The noble gas before \(Li\) is \(He\) (atomic number \(2\)).
• Argon (\(Ar\)) has an atomic number of \(18\). The noble gas before \(Ar\) is \(Ne\) (atomic number \(10\)).
• Iron (\(Fe\)) has an atomic number of \(26\). The noble gas before \(Fe\) is \(Ar\) (atomic number \(18\)).
• Barium (\(Ba\)) has an atomic number of \(56\). The noble gas before \(Ba\) is \(Xe\) (atomic number \(54\)).

Step2: Write the electron configuration

• For \(Li\): After \(He\), there is \(1\) electron left. The electron configuration is \([He]2s^{1}\).
• For \(Ar\): After \(Ne\), there are \(8\) electrons. The electron configuration is \([Ne]3s^{2}3p^{6}\).
• For \(Fe\): After \(Ar\), there are \(8\) electrons. The electron configuration is \([Ar]4s^{2}3d^{6}\).
• For \(Ba\): After \(Xe\), there are \(2\) electrons. The electron configuration is \([Xe]6s^{2}\).

Answer:

a. \([He]2s^{1}\)
b. \([Ne]3s^{2}3p^{6}\)
c. \([Ar]4s^{2}3d^{6}\)
d. \([Xe]6s^{2}\)