Number of lone pairs around ph6spborus in ${\mathrm{PCI}}_5$ , ${{\mathrm{PCl}}_4}^{+}$ and ${{\mathrm{PCl}}^{-}}_6$ are respectively:

All five of the valence electrons on the P atom—${\mathrm{PCl}}_5$—are involved in bonding.

${{\mathrm{PCl}}_4}^{+}$:+With a plus sign, one electron has been lost; the remaining four have been bonded.

${{\mathrm{PCl}}^{-}}_6$: - Gain of 1 electron, all 6 involved in bonding, is indicated by the minus sign.