What does an element's group number tell you about an element's chemical and physical properties ?

The chemical properties of elements are determined by their valence shell electronic configuration.

for example; the group 15 ( nitrogen family ),

The valence shell ( outermost shell ) electronic configuration of is ns2np3 , which clearly shows that all the elements have the tendency to make same kind if bonds with a common element.

That is, consider the hydrates of the group, it is NH3 ( ammonia ),PH3 (phosphine ), AsH3 (arsine ) , SbH3 ( stibine ) etc. They are having the same chemical formula and same type of bond (covalent bond )

The physical properties include melting point, boiling point, density etc.

Here for the same nitrogen family, all elements except nitrogen are solids in room temperature whereas nitrogen is gas.

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