question about free radicals

[fairy tale]

does anyone know for sure if the free radicals are charged, or if they have a zero charge?
thanks a lot 🙂

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[161927]

radicals by definition have an unbalanced charge (usually denoted as a single electron)

 

[spyderracing32]

Can you please link this definition because it seems like they shouldn't have a charge given each proton charge is balanced by exactly one electron charge.

 

[161927]

Can you please link this definition because it seems like they shouldn't have a charge given each proton charge is balanced by exactly one electron charge.

Are you serious bro?

 

[161927]

Free radicals are atoms or groups of atoms with an odd (unpaired) number of electrons and can be formed when oxygen interacts with certain molecules.

http://www.rice.edu/~jenky/sports/antiox.html

 

[fairy tale]

thank you guys.. can't tell here where I've seen this question, but I'm still confused. my orgo book says "a radical is a species containing an atom with an unpaired electron".. I also found that "in homolytic bond cleavage each atom retains one of the bonding electrons".. well, this still doesn't answer my question if the charge is -1, +1 or 0..😳
this test is so confusing..

 

[BrokenGlass]

thank you guys.. can't tell here where I've seen this question, but I'm still confused. my orgo book says "a radical is a species containing an atom with an unpaired electron".. I also found that "in homolytic bond cleavage each atom retains one of the bonding electrons".. well, this still doesn't answer my question if the charge is -1, +1 or 0..😳
this test is so confusing..

A halogen atom (e.g. F, Cl, Br, I) is a radical because it has 7 valence electrons, i.e. one of the electrons is unpaired. The charge on a lone halogen atom is zero. So a radical can have a charge of zero.

 

[mimimi]

thats not to say that radicals cant have charges on them. don't forget about things like superoxide radicals (O2)- radicals that are responsible for a lot of the reactive oxygen species chemistry responsible for tearing organic species up. usually radicals are neutral or negatively charged. don't think ive ever seen a positive one.

 

[TobiasFunkeMDFACS]

use the formal charge formula to calculate the charge on any atom(including radicals) =valence # - (bonds/2 + lone pairs).

So, radicals can be either +1, -1 or 0 based on the formal charge.

 

[bobsagat]

Actually, theoretically, you can draw a radical that has any charge you like. A hydrogen with 3 electrons? It'll have a charge of -2 and one unpaired electron.

Whether a species is a radical does not have any direct effect on its charge, positive, negative or neutral.

Also, when you start looking at aromaticity remember that any positively charged atom that allows the sing structure to have aromaticity could theoretically be replaced with a radical, and there would be no change to the aromaticity of the ring. At least this is what my TPR orgo teacher said.

 

[fairy tale]

finally asked my orgo teacher. she said free radicals are uncharged. so it's 0.

 

[TieuBachHo]

finally asked my orgo teacher. she said free radicals are uncharged. so it's 0.

I am very curious with this answer. What sort of explanation had she given you? Thank you!🙂

As I know, the charges on an atom depend on the difference between the number of protons and its electrons. By nature a radical is an electron but whether it contributes to the overall charge of an atom depends on the atom's state.

It's very ambiguous to say whether a radical carries a charge or not. For example, free radical can also be shared by two atoms as in aromatic compounds to stablize the charges. It depends on the momentary period that it spends there.

😕😕😕

 

[BloodySurgeon]

Radicals are "normally" uncharged... of course there are exceptions

 

[BerkReviewTeach]

finally asked my orgo teacher. she said free radicals are uncharged. so it's 0.

Make sure that her answer matches the question you proposed here. As an organic chemist, she is likely considering the free radicals that matter in chemistry, such as carbon-base alkyl free radicals, peroxides, and halogen atoms. All three of those carry no net charge. Her answer could be in the context of your class, which means that for the duration of the class, the neutral free radicals are what you should know.

But as a general question spread over all of chemistry and not just organic chemistry, there are definitely charged free radicals. As pointed out by mimimi, superoxide is a free radical with a negative charge.

Even in organic chemistry, there are short-lived free radical cations. In mass spectroscopy, the molecule is ionized by impact to form a molecular cation that happens to also be a free radical. That species quickly decomposes to smaller fragments, of which the machine detects the charged species. But that is definitely a case of a cationic free radical.
For MCAT purposes, you may need to think beyond the class information.