The capacity of a subshell to hold electrons is determined by the azimuthal quantum number ($l$).

1. Number of Orbitals: The number of orbitals in a given subshell is given by the formula $(2l + 1)$.
2. Electrons per Orbital: According to the Pauli Exclusion Principle, each orbital can accommodate a maximum of 2 electrons with opposite spins.
3. Calculation: $\text{Max Electrons} = 2 \times (\text{Number of Orbitals})$ $\text{Max Electrons} = 2 \times (2l + 1) = 4l + 2$

Evidence from Sources:

• d-subshell ($l=2$): Source confirms the $d$ subshell holds up to 10 electrons ($4(2) + 2 = 10$).
• f-subshell ($l=3$): Source and confirm the $f$ subshell holds up to 14 electrons ($4(3) + 2 = 14$).