The Quantum Mechanical Atom Principal Shells, Subshells, and Orbitals

The Quantum Mechanical Atom Principal Shells, Subshells, and Orbitals 

An orbital is a volume of space about the nucleus where the probability of finding an electron is high. Unlike orbits that are easy to visualize, orbitals have shapes that do not resemble the circular paths of orbits. In the quantum mechanical model of the hydrogen atom, the energy of the electron is accurately known but its location about the nucleus is not known with certainty at any instant. The three-dimensional volumes that represent the orbitals indicate where an electron will likely be at any instant. This uncertainty in location is a necessity of physics. 

The quantum mechanical description of the hydrogen atom is more complex than Bohr s picture, but it is a better picture. In the quantum mechanical model, there are several principal shells 

To help you get a better idea of this nested structure, the general characteristics of principal shells, subshells, and orbitals are described below. 

Within each principal shell are subshells. The number of subshells in a principal shell equals the value of its quantum number, n. Each subshell is identified with a one-letter label s, p, d, or f. Within known elements, the s-, p-, and d-subshells are encountered most often. 

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