Mnemonic for Lewis acids and bases

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Discussion Overview

The discussion revolves around the concept of mnemonics for understanding Lewis acids and bases within the context of acid-base chemistry. Participants explore various ideas related to the definitions and characteristics of acids and bases, particularly focusing on the role of lone pairs and protons.

Discussion Character

  • Exploratory
  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • Some participants propose that "Blob-like Bases" can serve as a mnemonic for understanding Lewis acids and bases, suggesting that bases envelop protons like a blob.
  • Others express confusion about the mnemonic and request clarification on its intended meaning.
  • It is noted that everything can be an acid or base depending on context, but not everything qualifies as a Lewis acid or base.
  • Some participants argue that a strong understanding of earlier acid-base theories makes the concept of lone pairs as bases intuitive, while others disagree, stating that mnemonics may still be necessary.
  • There is a discussion about the nature of acids and bases, with some emphasizing that Lewis acids accept electrons, while Brønsted acids are defined by their ability to donate protons.
  • A participant mentions fluoroantimonic acid as an example of a superacid, illustrating the complexity of acid-base interactions.
  • Concerns are raised about the general recognition of the "Blob" reference and its effectiveness as a mnemonic for those unfamiliar with it.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the usefulness of the mnemonic or the clarity of the concepts being discussed. Multiple competing views remain regarding the definitions and characteristics of Lewis acids and bases.

Contextual Notes

Some participants express uncertainty about the definitions and applications of acids and bases, highlighting the need for a deeper understanding of the underlying theories. There are also references to the limitations of mnemonics in conveying complex chemical concepts.

em3ry
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Blob-like Bases are the basis of Lewis acid-base chemistry.
The basis is that bases act like the blob. Their lone pair orbital envelops and swallows bare protons.

Basis-Bases-Blob

Lone pairs ARE the only true bases. They accept protons and other similar species. Water has protons and lone pairs so it is both acid & base. Ammonia has an extra lone pair that Boron trifluoride can accept

BF3_reacting_with_ammonia.svg


For thoses that dont get it: https://en.wikipedia.org/wiki/The_Blob

The film concerns a carnivorous amoeboidal alien that crashes to Earth from outer space inside a meteorite. It envelops living beings, growing larger.
The blob was eventually frozen and transported to Antarctica (the Thing?).
 
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@em3ry,
My technical knowledge has become weak in last few years, and I did read parts of the The_Blob wikipedia article. Interesting. Maybe you could explain what you want us to see or understand. and, what mnemonic?
 
To remember which one (acid or base) is lone pairs and which one is protons (or other similar species).
 
em3ry said:
To remember which one (acid or base) is lone pairs and which one is protons (or other similar species).
I still do not understand. Some of us studied and either slowly or quickly or intermediate, acquired an understanding of acids and bases. Bases may pull protons from certain compounds and these which their protons are pulled off from are acids. A compound with a proton easily pulled off because it's in the presence of some compound exposing some of its electrons, is an acid. Other members who have a stronger understanding can refine what I just said, much better. But I still do not conceive any mnemonic about this.

"The Blob" - this makes me think of growing bacterial and fungal colonies in a agar petri dish, or on infested (and spoiling) foods.
 
Everything can be an acid or base depending on context.
 
That may be true but not everything can be a Lewis acid or Lewis base
 
I am not convinced the reference is known widely enough for the mnemonic to be really helpful.

Plus, once you get to the Lewis acids and bases chances you still need mnemonics to remember which is which are pretty slim. Lewis theory is a generalization of several earlier concepts and builds on a rather broad picture - if you understand earlier theories, lone pair as a base is obvious. If you don't understand them - knowing the definition is of no use.
 
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Well I would strongly recommend starting with Lewis acids and bases since lone pairs are the underlying cause of the phenomenon.
 
em3ry, I do not know where you are trying to go with the topic.

Is water an acid or a base? Yes.

Is ethanol an acid or a base?
 
  • #10
SbF6_shells.svg


Fluoroantimonic acid is a mixture of hydrogen fluoride and antimony pentafluoride, containing various cations and anions (the simplest being H 2F+ and Sb F− 6). This mixture is a superacid that, in terms of corrosiveness, is trillions of times stronger than pure sulfuric acid when measured by its Hammett acidity function. It even protonates some hydrocarbons
 
  • #11
Lone pairs ARE the only true bases. They accept protons and other similar species.

Water has protons and lone pairs so it is both acid & base.
 
  • #12
BF3_reacting_with_ammonia.svg

A better diagram. Ammonia has an extra lone pair that Boron trifluoride can accept
 
  • #13
And boron trifluoride is notoriously electron deficient, making it a good Lewis acid.

Lewis acids accept electrons.
 
  • #14
Mayhem said:
And boron trifluoride is notoriously electron deficient, making it a good Lewis acid.

Lewis acids accept electrons.
Example of mnemonic, there!
 
  • #15
Yes acids accept but what do they accept? Protons or electrons?
That's exactly why I needed a mnemonic to help me remember.
A proton is a bare nucleus. Its tiny. Its not a blob. A lone pair is.
 
  • #16
em3ry said:
Yes acids accept but what do they accept? Protons or electrons?
That's exactly why I needed a mnemonic to help me remember.
A proton is a bare nucleus. Its tiny. Its not a blob. A lone pair is.
Electrons. Lewis acid/base theory only pertains to accepting/donating electrons whereas Brønsted acid/base theory pertains to donating/accepting protons.
 
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  • #17
Oh great. So now I need a mnemonic to remember that.
 
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  • #18
em3ry said:
Oh great. So now I need a mnemonic to remember that.
You could just remember things.
 
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  • #19
lol. No I cant
 
  • #20
@em3ry,
The post from @Mayhem is short, very very short, but that can stand for details (unstated) for how to study, and not focus on looking for mnemonics, in case you are putting too much emphasis on looking for mnemonics to substitute for trying to understand.
 

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