The 150^th anniversary of Mendeleev’s periodic table has catalysed many chemists to question all the different ways in which the elements can be arranged to maximise the usefulness of the table.  A good article on this by Joshua Howgego has appeared in the New Scientist.

Since elements are currently ordered in terms of atomic number many people think that logically the elements should be arranged to give 32 groups.

The long form of the periodic table (source doi.org/c2w9)

In the last IB chemistry curriculum chlorine was located in group 7. In the current programme it is in group 17. Maybe in the next programme (which has now been been officially delayed so that the first exam is now in May 2024 instead of May 2023) chlorine will find itself in group 31?