Periodic trend of acid strength

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305144105
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Periodic trend of acid strength

Postby 305144105 » Sat Dec 08, 2018 1:02 pm

When you move across a period, acid strength increases along with electronegativity.
When you move down a group, acid strength increases along with bond length (even though electronegativity increases).

Does the increase in bond length always negate the effect of increase in electronegativity?
Why is HBrO2 weaker than HClO2, despite it having a longer bond?

Ibrahim Malik 1H
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Re: Periodic trend of acid strength

Postby Ibrahim Malik 1H » Sat Dec 08, 2018 1:05 pm

In the case of HBrO2 and HClO2, it is the O--H bond that is getting broken, and because Cl has a higher electronegativity it is the more stable atom after the hydrogen atom leaves, making HClO2 the stronger acid.

Lauryn Shinno 2H
Posts: 47
Joined: Thu Sep 27, 2018 11:24 pm

Re: Periodic trend of acid strength

Postby Lauryn Shinno 2H » Sat Dec 08, 2018 1:25 pm

You can use bond length when referring to an A-H bond like HBr and HCl. However, HBrO2 and HClO2 have the same A-H bond being broken (O-H). Therefore, you have to use electronegativity to determine their strengths instead.


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