Group — গ্রুপ
A group is a vertical column of the table; its members share their outer-electron count and family chemistry.
Definition
A group (also called a family) is one of the 18 vertical columns of the periodic table. Because members share the same number of valence electrons, they behave alike: Group 1 metals all carry one outer electron and all burst into action with water; Group 17 halogens all need one more and all form salts with metals; Group 18 gases all hold full shells and stay aloof. NCTB texts still use the older IA, IIA style names alongside the modern 1–18 numbering, so learn to translate between them.
For example
Drop lithium, sodium and potassium in water in turn: a steady fizz, then a dancing skitter, then a lilac flame — one group, one habit, three volumes of drama.