Atom Size and Electronegativity to Rank Acid Strength in Organic Chemistry

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[@Leah4sci]

Happy to throw you the life-line!

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[@Leah4sci]

I really appreciate that, thank you! Memorization will only take you so far, but if you can understand and apply the material- THAT is what makes the difference!

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Thank you so much! I have my organic chemistry final tomorrow and I was still just a bit confused on this topic. Appreciate the clarification!!! :)

[@Leah4sci]

Awesome, glad I could help! How did your final turn out?

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That diagram you drew with the 10 elements and 2 trends to memorized was so simple yet so effective. Thank you!

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You're very welcome, I'm so glad you found it simple and helpful!

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[@Leah4sci]

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[@Leah4sci]

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Thank you so much, you are better at explaining the stuff more than my college professor

[@Leah4sci]

Happy to help!

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[@Leah4sci]

You're so welcome! Glad the videos have helped! For help with topics like this and more, I recommend joining the organic chemistry study hall. Details: leah4sci.com/join or contact me through my website leah4sci.com/contact/

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[@bv8560]

Hey Leah. I’m studying for the MCAT and your videos have been so helpful! In the video you mentioned “looking at the acidic hydrogen” how do you determine acidic hydrogens?

[@Leah4sci]

I'm sorry, but I don't offer tutoring through KZbin comments. For additional help with this topic, I recommend watching the series all the way through from the beginning. And if you still need help, I recommend joining the MCAT study hall. Full details: join.mcatstudyhall.com

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ma'am do you have any idea how well and how fluently you explain ??????? keep making more such videos ma'am ....... I am in12 th grade and find ur videos very helpful .....

[@Leah4sci]

Aww thanks so much for your kind words!

[@sderese]

How you make it simple is amazing

[@Leah4sci]

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[@Leah4sci]

Glad I could help!

[@MraghCottagh]

Thanks!! Your explanation was really clear and easy to understand :)

[@Leah4sci]

You're welcome, so happy to help!

[@schneid229]

In these examples you are comparing acids all in the same group or in the same period. What if you have to put 4 acids in order and they are 2 in the same group and 2 in the same period. How do you rank them?

[@mathenium7894]

3 years too late, but if they're in the same row, compare EN and if they're in the same group, look at the size

[@bonbonpony]

@@mathenium7894 What if they're in different columns and different periods? :D

[@Leah4sci]

Professors will typically test you on comparing trends and so won't mix and match. It's more complicated when looking across different rows and periods because the trends aren't as easy to understand. Typically electronegativity is 2 across to 1 down in terms of their rate of change, though I doubt you need to know this

[@wokelonzo]

really good explanation

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thank you so much

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Life saver ❣

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great video as usual

[@Leah4sci]

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[@alejandroalarcon1970]

great video!!!

[@Leah4sci]

Glad you liked it!

[@Soltanalipour]

How come electronegativity increases acidity? I though that the more localized the negative charge the less stable the base. If electronegativity is pulling electrons towards the nucleus does it not make the electrons more localized

[@bonbonpony]

You're right that atoms that are more electronegative pull electrons more towards them and don't want to give them back. This doesn't make _them_ strong acids though - it makes them weaker (more stable) conjugate bases, because they're more OK with this additional negative charge. If you take a proton from them, and the electrons that were making the bond with that hydrogen will get withdrawn by that atom, it will be like "sure, whatever…", chilling with those extra negative electrons. Which means that it's easier to detach hydrogens (protons) from them, and this increases acidity (more protons floating around). In short: the weaker the conjugate base, the stronger its conjugate acid (and vice versa).

[@kimberlypajinag3004]

This video is very helpful, thank you very much.

[@Leah4sci]

I'm glad you enjoyed it!

[@riyamittal7943]

Amazing video. Thank you so much.

[@Leah4sci]

Glad you liked it!

[@missbailey7280]

Leah I just started watching your videos and I want to understand organic chemistry are the videos in some kind of order

[@Leah4sci]

I have videos on all sorts of Organic Chemistry topics! For a comprehensive list, you can visit my Syllabus Companion Topics at Leah4sci.com/Syllabus For even more help, I recommend joining the organic chemistry study hall. Details: leah4sci.com/join or contact me through my website leah4sci.com/contact/

[@ertanissever7047]

I have a question . I am confusing about induction effect. Even if sulphur is bigger and it can distribute charge, oxygen is bigger electronegativity. When I compare, which one is more important ?

[@Leah4sci]

I'm sorry you're feeling confused. When you are comparing the acidity of atoms in the same period, their relative electronegativity is the more important factor. When you are comparing the acidity of atoms in the same group (like oxygen and sulfur), the relative size is the more important factor. Hope this clears things up for you.

[@ertanissever7047]

@@Leah4sci Thanks a lot.

[@almas702]

thank you so much, my professor had a stroke so his speech isnt very clear and he struggles to move his hands which makes learning from him very frustrating but you cleared everything very much

[@Leah4sci]

oh wow, that must have been hard for him and his students. Happy to help clear things up.

[@jamescavalari3977]

I don't understand the "size" trend. Shouldn't the "size" trend arrow go down and toward the right? isn't oxygen larger than carbon which is larger than boron etc.?

[@apollo5766]

No, they generally get smaller across the period from left to right. The number of electron shells is the same across each period, however, the atomic number is increasing which means there is an additional proton and electron for each successive atom across the period, and additional protons causes greater attraction on the electrons, reducing the atomic radius. Because the atoms are in the same period, additional electrons remain in the same shell, therefore electron screening stays pretty much constant, so the effective charge that the atoms have across the period increases, causing the atoms to get smaller across the period!

[@Leah4sci]

The size trend is down and towards the left. This means that atoms get bigger as you move leftward and as you move downward on the table. This has to do with Z-effective and the stronger pull of a larger nucleus on the valence electrons

[@raplopez4258]

But what if there is a tie? Like HF vs H2S? Which factor is more influential?

[@Leah4sci]

Thanks for watching and asking. In what way is there a tie between these two acids? As in the video’s examples, it’s best to consider the conjugate base of both molecules. The more stable the conjugate base, the stronger the acid. For more help on questions like this, consider joining my Organic Chemistry Study Hall at studyhall.leah4sci.com/join

[@bonbonpony]

Fluorine is more electronegative (3.98 for F, 2.58 for S, according to most of the tables I could find), which means that it will be less uncomfortable with that extra negative charge, and more stable, so it won't cry that much after losing the hydrogen. Which means that HF is more acidic.

[@raplopez4258]

@@bonbonpony thank you for explaining it like I'm 5 (not being sarcastic)

[@nathanullman7823]

Is there a reason the mnemonic is CARIO and not CAIRO (Egypt's Capital, easier to remember this way just wanted to make sure the order of the mnemonic does not matter) Thanks!

[@Leah4sci]

No reason other than it’s typically easier to spot resonance effects over inductive effects. The order of the mnemonic is unimportant, and you can use it however you see fit. :)

[@brade770]

Excellent. ty.

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nice voice n explanation

[@Leah4sci]

Glad you enjoyed it

[@bellefeu4933]

GROUPS are across the top as columns, PERIODS are down the rows. Killer video set!

[@Leah4sci]

Glad you like the videos! I think we mean the same thing here. Groups are columns, meaning they go ‘down’ the table (top to bottom). Periods are rows, meaning they go ‘across’ the table (left to right).

[@victorpaul6748]

Good work! More blessings

[@Leah4sci]

Thank you! :)

[@rohanmanab]

thank you so much

[@Leah4sci]

you're welcome!

[@billstark2399]

Why is comparing the electronegativities of 2 atoms in the same group problematic?

[@Leah4sci]

It’s not problematic, but less of an important factor because the greater size is preferable when it comes to the atom’s ability to hold negative charge. The large difference in size between atoms in the same group (rather than the much smaller difference in electronegativity) affects the molecule’s induction. Thanks for watching!

[@demlafields1806]

please break this down some more, please

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Thank you so much, you are better at explaining the stuff more than my college professor

[@Leah4sci]

Awww, thanks for your kind words! Happy to help!