The difference between Px Py and Pz orbitals lies in their orientation in three-dimensional space: Px is aligned along the x-axis, Py along the y-axis, and Pz along the z-axis, although all three share the same dumbbell-shaped structure. These orientations determine how electrons occupy space around the nucleus.
Understanding the distinction among Px, Py, and Pz orbitals is essential in chemistry because it influences bonding, molecular geometry, and electron distribution.
What Are Atomic Orbitals?
Atomic orbitals are regions around the nucleus where the probability of finding an electron is highest. Electrons occupy orbitals labeled as s, p, d, and f based on their shapes and energy levels.
Among these, the p-orbitals consist of three orientations—Px, Py, and Pz—each mutually perpendicular.
What is a Px Orbital?
The Px orbital is a p-type atomic orbital aligned along the x-axis. It has a dumbbell shape with two lobes positioned horizontally on opposite sides of the nucleus.
Key Features of the Px Orbital
- Orientation: x-axis
- Shape: Dumbbell
- Magnetic quantum number (m): +1 or –1
- Exists only when:
- Principal quantum number n ≥ 2
- Angular momentum quantum number l = 1
Example
In the carbon atom, the 2p subshell contains 2px, 2py, and 2pz orbitals. The 2px orbital participates in sigma bonding in molecules like C₂H₄ (ethene).
What is a Py Orbital?
The Py orbital is oriented along the y-axis and also has a dumbbell shape with two vertical lobes relative to the y-axis.
Key Features of the Py Orbital
- Orientation: y-axis
- Shape: Dumbbell
- Magnetic quantum number (m): +1 or –1
- Exists when:
- n ≥ 2
- l = 1
Example
In chlorine, the 3p orbitals include 3py, which contributes to the formation of covalent bonds in molecules like HCl.
What is a Pz Orbital?
The Pz orbital aligns along the z-axis. It also has a dumbbell structure but is oriented vertically in 3D space.
Key Features of the Pz Orbital
- Orientation: z-axis
- Shape: Dumbbell
- Magnetic quantum number (m): 0
- Exists when:
- n ≥ 2
- l = 1
Example
In molecules such as benzene, the 2pz orbital forms π-bonds, contributing to aromaticity.
Similarities Between Px, Py, and Pz Orbitals
All three p orbitals share important common features:
- Same shape (dumbbell)
- Same energy in isolated atoms (degenerate)
- Each has two lobes
- Size increases with increasing principal quantum number (n)
- Mutually perpendicular orientation
Difference Between Px Py and Pz Orbitals (Tabular Form)
| Feature | Px Orbital | Py Orbital | Pz Orbital |
| Orientation | Along x-axis | Along y-axis | Along z-axis |
| Shape | Dumbbell | Dumbbell | Dumbbell |
| Magnetic Quantum Number (m) | +1 or –1 | +1 or –1 | 0 |
| Lobes | Horizontal | Vertical (side-oriented) | Vertical (z-direction) |
| Role in Bonding (Example) | σ-bonds in ethene | σ-bonds in HCl | π-bonds in benzene |
Why Orientation Matters in Chemistry?
The orientation of Px, Py, and Pz orbitals plays a major role in:
- Molecular bonding (σ and π bonds)
- Hybridization (sp, sp², sp³)
- Molecular geometry (tetrahedral, trigonal planar, linear)
- Electron distribution and reactivity
For example:
- sp² hybridization uses Px and Py orbitals to form planar structures.
- π-bonds are formed mainly by the Pz orbitals overlapping sideways.
Conclusion — Difference Between Px Py and Pz Orbitals
The difference between Px Py and Pz orbitals is mainly their orientation: Px aligns with the x-axis, Py aligns with the y-axis, and Pz aligns with the z-axis, although all share the same dumbbell shape and similar energy. This distinct orientation influences bonding, hybridization, and molecular geometry. Understanding the difference between Px Py and Pz orbitals is fundamental for mastering chemical bonding and atomic structure.
Reference:
1. “Atomic Orbital.” Wikipedia, Wikimedia Foundation, 24 Apr. 2018,
2. Libretexts. “Atomic Orbitals.” Chemistry LibreTexts, Libretexts, 7 Feb. 2018,
3. Agray, Santosh. “Shapes of Orbitals.” Chemistry Desk,
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