IB skill practice

Explain expanded octets and electron-deficient species

Paper 1, Paper 2 5 marks Difficulty 4

Central atom electron count

In a organic structure seminar, BF3 is drawn with the central atom B. How many electrons are shown around the central atom? Use the labelled diagram or spectrum before giving the answer. Enter the answer and choose the interpretation that matches the HL chemistry evidence.

Worked practice: chemistry evidence and answer

Use the chemical evidence first, then enter the result and interpretation that match it.