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Questions tagged [isotope]

This tag should only be applied where the effects are specifically related to variance in mass number with the same atomic number (existence of isotopes). Examples include: radioactivity and other nuclear properties, kinetic effects, specific relevance to spectroscopy (e.g., NMR, IR), isotope separation, isotopic analysis.

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How many neutrons could a hydrogen atom hold?

Usually a hydrogen atom consists of no neutrons; however many exotic hydrogen isotopes have been synthesized. Deuterium and tritium are some of the more 'common' isotopes; nevertheless, Wikipedia's ...
11 votes
1 answer
270 views

How to apply the Cahn–Ingold–Prelog priority rules to an isotopically-labeled molecule?

Is the following the correct designation (S) for the chiral carbon in a skeletal representation of 1-chloro(3-13C)butan-2-amine? The CIP rules say to go one at a time by each rule until you find an ...
2 votes
1 answer
67 views

Electron affinity of isotopes anomaly

According to the Wikipedia article the electron affinity of $\ce{^{2}H}$ is higher than the electron affinity of $\ce{^{1}H}$ however the electron affinity of $\ce{^{18}O}$ is lower than $\ce{^{16}O}$....
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Comparison of oxygen and carbon-12 as standards for mass

While studying about the standards of atomic and molecular mass, I have learnt that while initially hydrogen was used as a standard of mass (its mass taken as unity), according to my book, oxygen was ...
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1 answer
76 views

Hydrogen–deuterium exchange in 1,4-benzoquinone

Problem Find number of deuterium exchanges in the following compound. Solution Question I have been taught that hydrogen attached to the carbon which is directly or indirectly in conjugation with ...
6 votes
1 answer
366 views

Stability of beryllium isotopes

I have been reading about isotopes and their abundance on Wikipedia. It states that lithium has 2 stable isotopes, beryllium has 1 stable isotope (monoisotopic and mononuclidic) and boron has 2 stable ...
2 votes
1 answer
105 views

Is a hydrogen atom 'locked' to a given oxygen atom in ice?

Ice, Hydrogen bond, and Ice rules Wikipedia articles seem to imply that the covalently bonded hydrogen atoms are fixed to their given oxygen atom and do not change positions as long as the ice remains ...
4 votes
1 answer
1k views

Correct Electron Configuration of Ni-28

I have seen two electron configurations for $\ce{_{28}Ni}$ in my chemistry textbook: $$[\ce{Ar}]~3d^8~4s^2$$ $$[\ce{Ar}]~3d^9~4s^1$$ Which of those is actually the correct one (in reality)? Why ...
1 vote
1 answer
95 views

Cesium Chloride Density Gradient Centrifugation and Isotopes

In Cesium Chloride Density Gradient Centrifugation, as used by Meselson and Stahl, Cesium ions can be seen as strongly affected by centrifugation, so much so that they can overcome their ionic bonds ...
1 vote
1 answer
382 views

2 modes of radioactive decay for hydrogen-5?

While looking at a table of helium isotopes it said that helium-8 turns into Tritium(hydrogen-3) and helium-5 through fission and beta decay. But the pathway to helium-5 isn't so direct. It is more ...
46 votes
2 answers
26k views

Inductive effect of hydrogen isotopes

Why does the electron-donating inductive effect (+I) of the isotopes of hydrogen decrease in the order $\ce{T} > \ce{D} > \ce{H}$? (where T is Tritium and D is Deuterium) Google has nothing to ...
3 votes
1 answer
183 views

The isotopic effect in chemical kinetics

I conducted a chemical experiment (degree in chemical engineering) to understand the isotopic effect in chemical kinetics. In the experiment, I reacted isopropanol and D-isopropanol (D stands for ...
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2 answers
188 views

Hydrogen Isotopes and Bronsted Lowry Acid

a Bronsted Lowry Acid is defined as an acid that donates a proton. However it's actually a Hydrogen Ion, since hydrogen only has 1 proton and 1 electron, a positive Hydrogen Ion would have no electron ...
3 votes
2 answers
222 views

NMR and dienes to isolate certain isotopes?

I am looking to achieve isotope separation using transition states. In the rxn of dienes with halogens, based on the temperature, the dienes can create a thermodynamic product or a kinetic product. ...
1 vote
1 answer
168 views

Is CD4 an alkane?

Can $\ce{CD4}$ or $\ce{CT4}$ be considered an alkane? I know that an alkane is $\ce{C_nH_p}$ where $p = 2n + 2$. An alkane is considered a "hydro"carbon, i.e., a compound containing purely ...
0 votes
1 answer
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Masses of atoms and molecules [duplicate]

This is my understanding so far: Average atomic mass is the mass of an element considering isotopes and is measured in atomic mass units. However relative atomic mass is the average mass of an atom ( ...
6 votes
2 answers
12k views

Which element has the highest binding energy per nucleon

The graph of binding energy per nucleon (Hyperphysics) seems to peak at Iron-56. However, Wikipedia says that Nickel-62 has the highest binding energy per nucleon of any known nuclide (8.7945 MeV). ...
6 votes
3 answers
529 views

Can one calculate the polarizability of Xe isotopes using Gaussian 09 and the 3-21G basis?

While trying to understand this paper, I read the following method for calculating the polarizability of different Xe isotopes: Quantum chemical calculation of the exact polarizability of each xenon ...
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323 views

Can deuterium be separated from heavy water via electrolysis? It is an isotope of hydrogen, so I guess it should act in the same way?

I was wondering if it is possible to separate deuterium from heavy water via electrolysis. Also, is this the way deuterium gas is obtained on an industrial scale, or are there better methods?
8 votes
1 answer
71 views

Are double spike isotopic standards suitable for quantification by isotope dilution mass spectrometry?

I would like to apply isotope dilution mass spectrometry (IDMS)* to quantify lead at trace levels. A good spike solution for the process would be the NIST SRM 991 which is an enriched material of ...
-1 votes
3 answers
921 views

How are the number of neutrons changed in an atom? [closed]

I'm studying isotopes in high school and I don't understand how it works. From my understanding, when neutrons are added or removed, an isotope is created. To calculate the number of neutrons, the ...
16 votes
2 answers
3k views

Francium has isotopes so how can its atomic mass be a whole number?

Why do francium, radon, radium, and actinium have whole numbers for average atomic mass even though they have isotopes? But then elements like beryllium, fluorine, and sodium are listed as having no ...
3 votes
0 answers
67 views

Is it possible to estimate how much Plutonium existed during the earth's formation?

Plutonium is a man-made element, but minute quantities of it exist on earth. It's probable the earth had much larger quantities of it during its formation as a planet, but most of it decayed due to ...
-1 votes
1 answer
141 views

Isotopes \ monoisotopic elements [closed]

I am confused about the definition of isotopes I know that isotopes are atoms of an element with different numbers of neutrons. What I don't understand is that we have monoisotopic elements which are ...
5 votes
1 answer
2k views

Dipole Moment of Normal Water vs Heavy Water

The question is in the title itself. My guess: Higher for Normal water. My Reasoning: Internet told me Deuterium is more electronegative than Protium. So, there should be less difference between ...
4 votes
1 answer
2k views

Meaning of m2 in the symbol for an isotope of an element

What does the notation $^{197\mathrm{m}2}\ce{Pb}$ mean? Specifically, the '$\mathrm{m}$2' part. I've found this and it appears to have something to do with charge distribution. The original notation ...
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1 answer
137 views

Can the word "iso" be used if the quantities are zero in number?

Both $\ce{H+}$ and $\ce{He^2+}$ ions have zero electrons. So can we call them isoelectronic species? And if two species have a difference in the number of protons and neutrons equal to zero, can we ...
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1 answer
92 views

Determining the average relative mass of an element from the percentage of isotopes

Suppose we have an element $\ce{A}$. Its relative mass is $16$ and it has three isotopes: $\ce{^16A}$ ,$\ce{^17A}$ and $\ce{^18A}$. The available percentage of $\ce{^17A}$ is $0.037\,\%$. What is the ...
88 votes
5 answers
20k views

Is it true that heavy water is not blue?

I believe I saw this claim somewhere on the internet a long time ago. Specifically, it was claimed that the difference could be observed by filling one long, straight tube with light water and one ...
11 votes
1 answer
618 views

Is there oxygen isotope exchange between dissolved CO2 and H2O?

If you had a sample containing an elevated concentration of $\ce{H2^{18}O}$, and bubbled $\ce{C^{16}O2}$ through it, would some of the oxygen-18 isotope be transferred from water to carbon dioxide? I ...
4 votes
0 answers
93 views

Mapping of half-life decay for all elements/isotopes

Is there an open resource that helps illustrate all paths of decay for all isotopes (e.g. $\ce{^{99}Mo}$ decaying to $\ce{^\mathrm{99m}Tc})?$ I know the result state/transition map would be massive, ...
1 vote
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92 views

Bond frequency vs Bond Strength in Kinetic Isotope Effect

I am confused by the following: in Ansyln's Modern Physical Organic Chemistry, a higher vibrational frequency defines a stronger bond due to the deeper/sharper potential well (page 76). However, the ...
6 votes
1 answer
707 views

Why is Gallium-69 stable, Gallium-70 unstable and Gallium-71 stable again?

Why is gallium 70 suddenly unstable, whereas it becomes stable again when you add another neutron? Shouldn't isotopes become unstable when there are either too few or too many neutrons? Why is gallium ...
1 vote
0 answers
80 views

Mass spec mass calculation difference

This is not a homework question, but for research. I am performing mass spec on serum metabolites using Thermo Q Exactive PLUS with a HESI source which was set to a spray voltage of -2.7kV under ...
2 votes
1 answer
72 views

g-tensor and hyperfine tensor for nitroxide spin label with 15N

Does anyone know where I can find numerical data for the $g$ tensor and hyperfine tensor for a nitroxide spin label where the nitrogen-14 atom has been replaced by a nitrogen-15 atom? I'm really ...
0 votes
2 answers
1k views

Neutron–proton ratio and isotope stability

I have studied that most of the isotopes (not all of them!) with a neutron–proton ratio of $\ge 1.5$ are unstable; but it is obvious that this is not true in some cases like carbon-14 or technetium-99....
28 votes
1 answer
8k views

How come uranium's relative atomic mass is 238.03 when it only contains isotopes with a mass number of 238 or less?

I have always been led to understand that the mass of an element on the periodic table is the weighted average atomic mass over all naturally occurring isotopes. This seems to make sense with all the ...
4 votes
0 answers
89 views

How is this Clemmensen Reduction taking place? [closed]

How did that isotopically labelled Carbon migrate? I know that an carbanion is formed, but I am not able to conclude the final product. Please Help
2 votes
2 answers
1k views

How do we know the natural abundance of isotopes on Earth?

Without knowing the Average Atomic Mass or the percent abundance, how do we know that Protium is the most prevalent hydrogen isotope? What methods did scientists use to come to this conclusion? How ...
1 vote
0 answers
48 views

Does the Atomic Mass listed for each element on the periodic table reflect the relative abundances of their isotopes on Earth? Or in the Universe? [duplicate]

Somehow, I cannot find a site or book or paper explaining exactly how the average atomic masses for the elements on the periodic table are weighted.... I posted a question either here or on Physics S....
0 votes
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48 views

Where do the electrons for which RTG's use for the Seeback effect come from?

I know that RTG's use Radioactive Isotope that emit Alpha particles generally (ie. NASA uses Pu 238), I also know that these Alpha particles are consiting of 2 Protons and 2 Neutrons, since the RTG ...
4 votes
3 answers
340 views

If all molecules have basically the same KE at a given temperature, why do lighter isotopes evaporate more readily?

One of the proxies used for paleoclimate is the ratio of oxygen-18 to oxygen-16 in ice cores and in sedimentary rocks. The idea is that water molecules with oxygen-18 generally evaporate less readily ...
5 votes
3 answers
19k views

What is the relationship between entropy and heat capacity?

The molar heat capacity of hydrogen gas and deuterium gas are nearly the same, $\pu{28.8 J K-1 mol-1}$ and $\pu{29.2 J K-1 mol-1}$, respectively, but the absolute entropy of deuterium ($\pu{145.0 J K-...
1 vote
1 answer
154 views

Can the enrichment of Uranium be done via manipulating the boiling/melting point difference between differing isotopes of the same element?

I have a Physics question for which I could not find the answer on the Internet, so I would like to see if y'all know the answer to it. I have found that heavy water will have a different boiling ...
3 votes
2 answers
305 views

Long-lived, non-lethal radioisotope for fiction [closed]

I'm writing something where the characters are looking for someone among a large set of people. They don't know who this person is and they don't know what they're looking for, so their best bet is to ...
3 votes
2 answers
117 views

Biological activity of the isotopes of the same element

I have a question regarding biological activity of different isotopes of the same elements, notably $\ce{^206Pb}$ and $\ce{^208Pb}$. Lead is known to be toxic, such that it can replace calcium from ...
3 votes
1 answer
262 views

What is the heaviest possible water using oxygen and hydrogen isotopes, and what might it's physical properties be? [closed]

After a cursory internet search, it appears to me that Hydrogen-3 (a part of Tritiated Water) is the heaviest stable* hydrogen isotope. Oxygen-21 is the heaviest isotope of Oxygen with a half-life of ...
-1 votes
1 answer
300 views

What does radioactive decay look like?

Some element isotopes have half-lives that are as short as a couple minutes to an hour. Does that mean you can watch it (or catch it on video) turn into 2 different elements? What would something like ...
4 votes
0 answers
36 views

Normalising Kinetic Isotope Effect Per Deuterium Atom

I've synthesised a protic and deuterated version of a specific molecule where there are two deuterium atoms in the latter. I then go about and measure the kinetic isotope effect (KIE) for a reaction ...
1 vote
1 answer
13k views

Can an ion isotope exist?

Can an isotope have a charge, i.e. the number of neutrons and electrons differ in that atom? If it does exists, is it correct to call it an ion isotope or isotope ion?