Node
Definition and meaning of Node in chemistry.
A node is a region in an atom or molecule where the electron probability density is zero, appearing as a plane, surface, or point where the wave function equals zero.
In more detail
In quantum mechanics, electrons are described by wave functions that vary in space. A node occurs where this wave function passes through zero. The number of nodes in an orbital increases with its energy level and principal quantum number, so higher energy orbitals contain more nodes. Nodes are essential for understanding orbital geometry and how electrons distribute in bonding and antibonding orbitals.
Key facts
| Field | Physical Chemistry |
|---|---|
| Electron probability at node | Zero |
| Total nodes per orbital | (n-1) where n is principal quantum number |
| Node types | Radial surfaces and angular planes |
The 2p orbital has one nodal plane passing through the nucleus that divides the orbital into two lobes. In molecular orbital theory, a bonding orbital has fewer nodal surfaces between atoms than an antibonding orbital of the same symmetry.
Frequently asked questions
How do nodes relate to orbital energy?
Orbitals with higher principal quantum numbers and higher energies contain more nodes. For example, the 3s orbital has two radial nodes while the 2s has only one.
Which orbital has no nodes?
The 1s orbital has no nodes. All other orbitals in atoms contain at least one nodal feature.