Draw the Lewis structures, predict the shape and deduce the bond angles for xenon tetrafluoride and the nitrate ion.

Accept any combination of lines, dots or crosses to represent electron pairs.

Many candidates had difficulties with the Lewis structure of the nitrate ion, putting too many electrons around the nitrogen atom or omitting the negative charge. They did better with XeF4, giving correct shape and bond angles. Some candidates lost marks for omitting lone pairs from the F atoms, and some had only 4 negative charge centres around Xe. Some teachers expressed concern that only exceptions to rules were being examined, but both \({\text{NO}}_3^ - \) and \({\text{Xe}}{{\text{F}}_{\text{4}}}\) are listed as examples to use in the teacher‘s notes.