Explain the patterns and trends within groups 1 and 7 in the periodic table.?

atomic structure and the chemistry of the elements and thier compounds.

Answers:
Well if u look in any A-level or above text book the explanation 2 ur question would b in there.
Is it someone's homework time maybe?!!
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Group VII
a) Decrease in reactivity/oxidising power.. this is because as you go down the group each element as 1 more shell of electrons in the atom. This shields the nucleus and increases the distance to the outer shell. Both these factors reduces the attraction for incoming electrons even though there are 8 or more positive protons in the nucleus.
b) Increase in melting point/boiling point. this is because as you go down the group each element as 1 more shell of electrons in the atom. The atomic/van der waals radius increase and the outer electrons are more losely held in the outer shell. Result Van Der Waals forces between molecules are greater due to a greater surface area over which then occur and there are greater temporary diploles set up. These greater Van Der Forces mean more energy is required to overcome the forces of attraction between the molecules thus elevating the melting and boiling point.
C) Colours of the vapours become darker ..Yellow to green to orange to purple...reason..no idea!
D) Reducing power of the Halides increases down the group...this is because as you go down the group each element as 1 more shell of electrons in the atom. This shields the nucleus and increases the distance to the outer shell. Both these factors alow electrons to be more easily lost from the halides as beautifully demonstrated with the progressive reduction of Conc Sulphuric Acid to Sulphurdioxide with HBr to Sulphur and Hydrogen Sulphide with HI. (HCl does not reduce Conc Sulphuric Acid).
I'll let someone else do Group I
I may not list all the patterns, but here are two:
1)The substances gets less reactive
2)One more electron is added than the element before it in the period

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