Читать книгу Foundations of Chemistry - Philippa B. Cranwell - Страница 115

The first thing to determine is how many areas of electron density are around the central phosphorus atom using a dot‐and‐cross diagram. Phosphorus is in Group 5 (Group 15) and therefore has five outer‐shell electrons. Each fluorine has seven outer‐shell electrons and therefore wants to gain one electron to complete the octet. Fluorine achieves this by sharing each of its unpaired electrons with one from phosphorus, generating a pentavalent central phosphorus atom. There are no lone pairs of electrons, so the five single bonds arrange themselves in a trigonal bipyramidal shape.