There are 18 groups in the periodic table according to the modern standard adopted by the International Union of Pure and Applied Chemistry (IUPAC).
Here's why there might be confusion:
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Older Conventions: Historically, some periodic tables displayed elements in 8 groups. This older system often combined some of the groups now separated in the 18-group system.
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IUPAC Standard: The 18-group system is the internationally recognized and preferred method for organizing the periodic table. This system provides a more consistent and accurate representation of the elements' properties and relationships.
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Why the change? The 18-group system provides a clearer organization that reflects the electronic configuration of the elements and their resulting chemical properties. The older 8-group system could lead to ambiguities and inconsistencies, particularly when dealing with transition metals.
In summary, while older textbooks or materials might reference an 8-group system, the 18-group periodic table is the current and correct standard. Refer to credible sources like the IUPAC website or modern chemistry textbooks for the most up-to-date information.
