Orbital Subshell Energy

Quantized Orbital Energy

• Electron energy and orbital energy are quantized, meaning they have specific discrete values.

• Increasing the principal quantum number (n) increases energy, but the energy increment decreases with each successive shell.

Hydrogen Atom Orbitals

• For a hydrogen atom only, all subshells (s, p, d) within the same principal energy shell (e.g., $n = 3$) have identical energy.

Multi-Electron Atom Orbitals

• For multi-electron atoms, subshell energies within the same principal energy shell are not equal.

• Subshell energies typically increase in the order: s < p < d < f.

• In some multi-electron atoms, the energy of the $3d$ subshell can be higher than the energy of the $4s$ subshell.

Orbital Shapes and Nodes

• All s orbitals are spherical.

• All p orbitals are "dumbbell" shaped.

• As the principal quantum number increases for a given orbital type (e.g., $1s, 2s, 3s$), the orbitals increase in size and gain an additional internal node.