Chemistry · Periodic Classification Of Properties · NEET
Yes. Old IA and new group 1 are the same column - the alkali metals like Li, Na, K. IUPAC just renamed it '1' instead of 'IA'. The elements did not move. Only the label changed to make it clearer.
In the old system, A and B split the table into two families that shared a Roman number. IA was the alkali metals (Na, K - group 1 today). IB was the coinage metals (Cu, Ag, Au - group 11 today). They had the same Roman number 'I' but were totally different elements. This double use of numbers confused many students, which is exactly why IUPAC dropped A/B and switched to a single 1-18 count.
Old group VIII was the three tall columns of Fe, Co, Ni type elements (and the ones below them). In the new system these become three separate groups: 8, 9 and 10. Old group 0 was the noble gases (He, Ne, Ar). It is now group 18. So nothing was removed - the old odd labels were just given normal numbers.
The old A/B system was not the same in every country - the American and European tables used A and B for different columns. This caused mistakes. IUPAC fixed it by numbering each vertical column once, left to right, from 1 to 18. This is one clear world-wide system with no letters. For NEET, always use these 1-18 numbers.
For the main-group left side, IA->1, IIA->2. For the p-block right side, IIIA->13, IVA->14, VA->15, VIA->16, VIIA->17, and 0->18. For the d-block, IIIB->3, IVB->4, VB->5, VIB->6, VIIB->7, VIII->8,9,10, IB->11, IIB->12. Tip: the p-block A-groups jump to 13-18 because the ten d-block columns (3-12) sit in between.
Try the real previous-year questions from this chapter — each with the answer and a full solution.
No. The positions of all elements stay exactly the same. Only the name of each column changes from the old A/B labels to a plain number 1 to 18.
Use the IUPAC 1 to 18 numbering. NCERT and NEET both follow it. But you should still recognise old labels like IA or VIIA because some questions or reference books mention them.
In the modern IUPAC system they are group 18. The old label '0' is no longer used. Group 18 sits at the far right end of the table.
Because the ten d-block columns (groups 3 to 12) come before them. So after group 2, you count through the d-block first, and the p-block starts again at 13.
No. Group 1 is the alkali metals (Li, Na, K). Group 11 is Cu, Ag, Au. In the old system these were IA and IB - both 'I' but different elements. The new numbers 1 and 11 keep them clearly separate.
