Atomic Orbitals Explorer
An orbital is a 3D map of where an electron is likely to be found. Each dot below is one possible position, drawn from the real hydrogen wavefunction.
Clouds, not orbits
Quantum mechanics does not give the electron a path. It gives a probability of finding it at each point, equal to |ψ|². Where the dots crowd together the electron is most likely to be; the boundary we usually draw encloses about 90% of the cloud. Colours show the sign (phase) of ψ, which matters when orbitals overlap to form bonds.
Counting nodes
A node is a surface where ψ = 0, so the electron is never found there. An orbital with quantum numbers n and l has n − l − 1 radial nodes (spheres) and l angular nodes (planes or cones): n − 1 in total. Look for the empty shells inside 2s and 3s, and the empty planes through the nucleus in p and d orbitals.
Distances are in units of the Bohr radius a₀ = 52.9 pm. Blue = ψ positive, orange = ψ negative.