Question

Why do not elements present in a periodic show similar characteristics

Answer 1

present this element have similar physical property but different atomic number this message s isotopes

Answer 2

$\color{red}{ANSWER}$

The groups represent elements with the same number of electrons in their outer-most shell, called the valence shell. Hydrogen (atomic number-1) shows similarity in properties to group-1 and group-17 elements, hence is positioned separately on top of the table.

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