BridgeParticles, bonding and structureFree

Phosphorus chlorides: molecules and ions

Lewis structures, shape, polarity and bonding

Phosphorus forms two chlorides.

\ce{PCl3}

is a liquid at room temperature (boiling point 76 °C).

\ce{PCl5}

is a white solid that sublimes at about 160 °C. X-ray studies show solid

\ce{PCl5}

is not made of

\ce{PCl5}

molecules; it is made of

\ce{PCl4+}

and

\ce{PCl6-}

ions.

Facts you may need

Draw Lewis diagrams for

\ce{PCl4+}

and

\ce{PCl6-}

. For each, state the shape and the bond angle.

\ce{PCl3}

molecules are polar but

\ce{PCl5}

molecules (in the gas phase) are non-polar. Explain this difference.

Explain why phosphorus can form

\ce{PCl5}

and

\ce{PCl6-}

, but nitrogen (also group 15) forms only

\ce{NCl3}

Explain why solid

\ce{PCl5}

has a much higher melting/sublimation temperature than the boiling point of

\ce{PCl3}