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Is PH3 Polar or Nonpolar?
Phosphine has a trigonal pyramidal shape due to a lone pair on phosphorus. The electronegativity difference between P (2.19) and H (2.20) is essentially zero, so the polarity comes almost entirely from the asymmetric geometry and the lone pair contribution, not from bond polarity. The result is a modest dipole of 0.58 D.
Why is PH3 Polar?
Phosphine has a trigonal pyramidal shape due to a lone pair on phosphorus. The electronegativity difference between P (2.19) and H (2.20) is essentially zero, so the polarity comes almost entirely from the asymmetric geometry and the lone pair contribution, not from bond polarity. The result is a modest dipole of 0.58 D.
- Electronegativity difference: H (2.2) is significantly more electronegative than P (2.19), creating partial charges on each atom and making the individual bonds polar.
- Trigonal Pyramidal shape (93°): The asymmetric molecular geometry means the bond dipoles point in directions that do not cancel — they add up to produce a net dipole moment of 0.58 D.
- Net dipole moment (0.58 D): Any molecule with a nonzero net dipole moment is classified as polar. The 0.58 D dipole moment of PH3 confirms its polar character.
Molecular Geometry of PH3
PH3 has a trigonal pyramidal molecular geometry with a bond angle of 93°. Here is why this shape determines polarity:
- The central atom's electron pairs arrange themselves to minimize repulsion, resulting in the trigonal pyramidal shape.
- The 93° bond angle creates an asymmetric arrangement — the bond dipoles point in directions that do not perfectly oppose each other.
- Asymmetry is the key: if PH3 had a perfectly symmetric geometry, its bond dipoles would cancel and the molecule would be nonpolar. The trigonal pyramidal shape prevents this cancellation.
Electronegativity and Polarity
Electronegativity measures how strongly an atom attracts bonding electrons. A difference greater than ~0.5 on the Pauling scale generally means the bond is polar.
In PH3:
- P (central atom) electronegativity: 2.19
- H (outer atom) electronegativity: 2.2
- Difference: 0.01 — below the ~0.5 threshold, so the P–H bonds are only weakly polar
The combination of polar bonds and an asymmetric trigonal pyramidal geometry means the partial charges do not cancel — making PH3 a polar molecule with a net dipole of 0.58 D.
Is PH3 Polar or Nonpolar? (Quick Answer)
PH3 (Phosphine) is polar. PH3 is a polar molecule because its trigonal pyramidal geometry and the lone pair on phosphorus create a net dipole moment of 0.58 D, despite the nearly equal electronegativities of P and H.
Frequently Asked Questions
Is PH3 polar or nonpolar?
PH3 is a polar molecule because its trigonal pyramidal geometry and the lone pair on phosphorus create a net dipole moment of 0.58 D, despite the nearly equal electronegativities of P and H.
Why is Phosphine polar?
Phosphine has a trigonal pyramidal shape due to a lone pair on phosphorus. The electronegativity difference between P (2.19) and H (2.20) is essentially zero, so the polarity comes almost entirely from the asymmetric geometry and the lone pair contribution, not from bond polarity. The result is a modest dipole of 0.58 D.
What is the shape of PH3?
PH3 has a trigonal pyramidal molecular geometry with a bond angle of 93°. This shape results in an asymmetric charge distribution and a net dipole moment of 0.58 D, making the molecule polar.
Does PH3 have a dipole moment?
Yes. PH3 has a dipole moment of 0.58 D. Its trigonal pyramidal geometry and polar bonds combine to produce a net dipole, confirming its polar character.