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PCl5 Lewis Structure

Phosphorus pentachloride · A chlorinating reagent in organic chemistry.

Lewis structure of PCl5 (Phosphorus pentachloride)The bond dipoles are all the same size and the shape places them symmetrically around the central P, so they cancel exactly.PClClClClCl

The PCl5 Lewis structure has 40 valence electrons, drawn as five P–Cl bonds, with 15 lone pairs in total. The central P is sp3d hybridized, which makes it a trigonal bipyramidal molecule with a bond angle of 90 and 120 degrees. PCl5 is nonpolar: the bond dipoles are all the same size and the shape places them symmetrically around the central P, so they cancel exactly.

Calculated properties

Calculated properties of PCl5
Total valence electrons 40
Bonding electrons 10 (5 shared pairs)
Nonbonding electrons 30 (15 lone pairs)
Lone pairs on P 0
Electron domains (steric number) 5
VSEPR notation AX5
Electron geometry trigonal bipyramidal
Molecular geometry trigonal bipyramidal
Bond angle 90 and 120°
Hybridization sp3d
Polarity nonpolar
Formal charges all zero
Resonance structures none
Molar mass 208.224 g/mol

How to draw the PCl5 Lewis structure

  1. Count the valence electrons

    Add up the outer-shell electrons every atom brings. That total is the budget for the whole structure - every line and every dot has to come out of it, and nothing may be added.

    5 (P) + 5 x 7 (Cl) = 40 valence electrons

  2. Choose the central atom

    P is the least electronegative atom here, so it takes the centre. Hydrogen is never central: it can only form one bond.

  3. Join everything with single bonds first

    Every connection starts as one shared pair. Draw them all before worrying about double bonds - the arithmetic in the next step is what tells you where the double bonds have to go.

    5 bonds x 2 = 10 electrons used, 30 left

  4. Work out how far short you are

    Add up what every atom still needs to fill its shell - eight electrons for most atoms, two for hydrogen - minus what its single bonds already give it. Compare that with the electrons you have left. The difference decides everything that follows.

    needs 30, has 30, exactly enough

  5. Fill in the lone pairs

    Every electron not in a bond sits as a lone pair on an atom. Each atom takes exactly what it needs to finish its shell - there is no choice left at this point.

    Cl1: 3, Cl2: 3, Cl3: 3, Cl4: 3, Cl5: 3 (30 electrons)

  6. Check the central atom

    P ends up with 10 electrons, an expanded octet. Only period 3 and below can do this.

    P: 10 bonding + 0 nonbonding = 10

  7. Check the formal charges

    Formal charge is valence electrons, minus lone-pair electrons, minus the number of bonds. Every atom here comes out at zero, which is the sign of a good structure.

    all formal charges = 0

  8. Work out the shape

    Count the electron domains on P: 5 bonded groups. A double or triple bond still counts as one domain, because it points in one direction. That gives trigonal bipyramidal electron geometry; ignore the lone pairs and the atoms themselves sit in a trigonal bipyramidal arrangement.

    steric number 5 -> sp3d -> trigonal bipyramidal, bond angle 90 and 120

  9. Decide whether it is polar

    The bond dipoles are all the same size and the shape places them symmetrically around the central P, so they cancel exactly.

    dipoles cancel -> nonpolar

Is PCl5 polar or nonpolar?

PCl5 is nonpolar. The bond dipoles are all the same size and the shape places them symmetrically around the central P, so they cancel exactly.

BondElectronegativity differenceCharacter
P–Cl 0.97 polar covalent
Why this molecule gets set as a problem: Five bonds, two different bond angles, and an expanded octet.

Common questions

How many valence electrons does PCl5 have?

PCl5 has 40 valence electrons. 10 of them are in bonds and 30 sit in lone pairs.

What is the molecular geometry of PCl5?

PCl5 is a trigonal bipyramidal molecule. The central P has 5 bonded groups, a steric number of 5, which gives trigonal bipyramidal electron geometry and a trigonal bipyramidal molecule.

What is the bond angle in PCl5?

The bond angle in PCl5 is 90 and 120 degrees. That is the ideal trigonal bipyramidal angle, and nothing distorts it here.

What is the hybridization of PCl5?

The central P in PCl5 is sp3d hybridized. Steric number 5 means 5 orbitals have to be mixed, which is exactly what sp3d gives you.

Is PCl5 polar or nonpolar?

PCl5 is nonpolar. The bond dipoles are all the same size and the shape places them symmetrically around the central P, so they cancel exactly.

Why does PCl5 break the octet rule?

The central atom has more than four bonded groups, so it has to hold more than eight electrons. Elements from period 3 downward can do this; period-2 elements like carbon, nitrogen and oxygen cannot.

How this page was produced. The formula was parsed, the connectivity resolved (central atom), and every bond-order arrangement enumerated and scored on octet satisfaction, formal charge and where that charge sits. The structure above is the winner. Bond angles, hybridization and the polarity verdict are read off the resulting geometry, not looked up.