why is it that hydrogen can be placed in the first group as well as the 17th group?

Asked by  | 3rd Nov, 2009, 05:26: PM

Expert Answer:

Hydrogen can be placed in Group 1 because its configuration resembles that of Group 1 elements.Group 1 elements have general outer electronic configuration of ns1 and hydrogen has an electronic configuration of 1s1.

Hydrogen resembles halogens that is Group 17 elements because it requires one electron to complete its outermost shell. Its outermost shell is K shell which can have a maximum of two electrons. Group 17 elements also need one electron to  attain 8 electrons in their outermost shell.

It also has some properties which neither resembles Group 1 nor group 17. Hence, it is placed on the top of the modern periodic table separately.

Answered by  | 4th Nov, 2009, 01:08: PM

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