S Orbital Definition in Chemistry

At any given moment, an electron can be found at any distance from the nucleus and in any direction according to the Heisenberg Uncertainty Principle. The s orbital is a spherically-shaped region describing where an electron can be found, within a certain degree of probability. The shape of the orbital depends on the quantum numbers associated with an energy state. All s orbitals have l = m = 0, but the value of n can vary.

S Orbital Versus P Orbital

While orbital numbers (e.g., n = 1, 2, 3) indicate the energy level of an electron, the letters (s, p, d, f) describe the orbital shape. The s orbital is a sphere around the atomic nucleus. Within the sphere there are shells in which an electron is more likely to be found at any given time. The smallest sphere is 1s. The 2s orbital is larger than 1s; the 3s orbital is larger than 2s.

The p orbital has a dumbell shape and is oriented in a particular direction. At any one energy level, there are three equivalent p orbitals that point at right angles to each other (px, py, pz). As with the s orbital, the p orbital describes a region in space around the nucleus in which an electron may be found with the highest probability.