Which energy value is associated with the M-shell binding energy of tungsten?

Which energy value is associated with the M-shell binding energy of tungsten?

• A. 3.0 keV
• B. 0.5 keV
• C. 12.0 keV
• D. 69.5 keV

Answer: (A)

Understanding shell binding energies helps predict where electrons are held most tightly in tungsten (Z = 74). Inner shells have higher binding energies, with the K-shell around 69.5 keV, the L-shell near 12 keV, and the M-shell much lower. The M-shell binding energy for tungsten is about 3 keV, which is why 3.0 keV is the correct value. The other numbers correspond to energies of deeper inner shells (69.5 keV for the K-shell) or higher-energy transitions in the L-shell region (around 12 keV) or are simply too small for the M-shell.

Understanding shell binding energies helps predict where electrons are held most tightly in tungsten (Z = 74). Inner shells have higher binding energies, with the K-shell around 69.5 keV, the L-shell near 12 keV, and the M-shell much lower. The M-shell binding energy for tungsten is about 3 keV, which is why 3.0 keV is the correct value. The other numbers correspond to energies of deeper inner shells (69.5 keV for the K-shell) or higher-energy transitions in the L-shell region (around 12 keV) or are simply too small for the M-shell.