Orbitaali

Orbitaali is a term used in physics and chemistry (often written as orbital in English) to describe the quantum-mechanical region of space around an atom's nucleus where the probability of finding an electron is high. An orbitaali corresponds to a mathematical function, the electron's wavefunction, whose squared magnitude gives the electron density. Orbits are not literal paths, but probabilistic clouds determined by the atom's energy and angular momentum.

Each orbitaali is characterized by quantum numbers n, l, m_l, and a two-valued spin state. The angular momentum quantum number l defines the shape class: s (l=0, spherical), p (l=1, dumbbell), d (l=2, cloverleaf), f (l=3, more complex). The wavefunction can include radial and angular parts, leading to radial nodes and angular nodal planes. An orbital can hold up to two electrons with opposite spins, in accordance with the Pauli exclusion principle. In atoms, the energy ordering of orbitals depends on nuclear charge and electron screening, yielding configurations such as 1s, 2s, 2p, 3s, 3p, 4s, 3d, etc.

In chemistry, orbitals form the basis for understanding chemical bonding and the electronic structure of atoms. In molecular orbital theory, atomic orbitals combine to form molecular orbitals that extend over a molecule. In computational chemistry, orbitals serve as basis functions for methods such as Hartree–Fock and density functional theory. Visualizations of orbitals as isosurfaces are common to illustrate electron distribution and bonding patterns.