Place the species in each of the following groups in order...

Place the species in each of the following groups in order of increasing base strength. Give your reasoning in each case.
a. $\mathrm{IO}_{3}^{-}, \mathrm{BrO}_{3}^{-}$
b. $\mathrm{NO}_{2}^{-}, \mathrm{NO}_{3}^{-}$
c. $\mathrm{OCl}^{-}, \mathrm{OI}^{-}$

Key Concepts

Conjugate Acid?Base Relationship

This concept explains that the strength of a base is inversely related to the strength of its conjugate acid. In other words, if a conjugate acid is weak (less likely to donate a proton), its corresponding base is relatively strong. This relationship is crucial when assessing the basicity of species derived from acids of differing strengths.

Resonance Stabilization

Resonance stabilization involves the delocalization of negative charge over several atoms. When a charged species is resonance?stabilized, the charge is spread out over multiple centers, making it less reactive and consequently a weaker base. Understanding how resonance influences charge distribution helps in comparing the basicity of related species.

Inductive Effects

Inductive effects refer to the electron?withdrawing or electron?donating influences transmitted through sigma bonds in a molecule. Electronegative atoms, when attached to a negatively charged center, can pull electron density away and stabilize the charge, thereby reducing basicity. Recognizing these effects is key in predicting basic strength in oxygenated or halogenated ions.

Periodic Trends and Electronegativity

Periodic trends, such as electronegativity and atomic size, play a significant role in determining basicity. Atoms with higher electronegativity can better stabilize an adjacent negative charge through drawing electrons, which often results in a decrease in base strength. Conversely, atoms that are less electronegative provide less stabilization, thus favoring a higher basicity. This concept is particularly useful when comparing species with different central atoms or attached substituents.

Transcript

00:01 All right, guys, zoom 132 of chapter 4.

00:03 So now place the species in the following groups in order of increasing base strength.

00:08 So first off, we got i -o -3 -1 and b -r -3 -1.

00:18 So the difference between these two is that one has bromine and one has iodine.

00:23 So iodine is lower on the periodic table than bromine.

00:27 Now remember, as you go lower on the periodic table, your atomic radius increases.

00:33 And consequently, so does your acidity.

00:35 Because those valence electrons are not going to be held as tightly the larger your atom is because your valent shells getting further and further away from your nucleus.

00:51 So that means that at i .03 minus, that's going to be more.

01:02 Acidic, sorry, that's going to be, that's going to be more acidic than bro3 -03.

01:15 So that means that that's br -o -3 minus, that's going to have a higher basicity.

01:23 Now, no2 and no3 minus and no3 minus.

01:42 So, so remember the rule, the weaker, the action.

01:50 The stronger the conjugate base.

01:53 So as inconsequently, the stronger the base, the weaker the conjugate acid.

01:58 So what's going to be the conjugate acid in these cases? so no2 minus the conjugate acid is going to be hno2...

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