What is Isotope: Definition and 107 Discussions

Isotopes are two or more types of atoms that have the same atomic number (number of protons in their nuclei) and position in the periodic table (and hence belong to the same chemical element), and that differ in nucleon numbers (mass numbers) due to different numbers of neutrons in their nuclei. While all isotopes of a given element have almost the same chemical properties, they have different atomic masses and physical properties.The term isotope is formed from the Greek roots isos (ἴσος "equal") and topos (τόπος "place"), meaning "the same place"; thus, the meaning behind the name is that different isotopes of a single element occupy the same position on the periodic table. It was coined by Scottish doctor and writer Margaret Todd in 1913 in a suggestion to chemist Frederick Soddy.
The number of protons within the atom's nucleus is called atomic number and is equal to the number of electrons in the neutral (non-ionized) atom. Each atomic number identifies a specific element, but not the isotope; an atom of a given element may have a wide range in its number of neutrons. The number of nucleons (both protons and neutrons) in the nucleus is the atom's mass number, and each isotope of a given element has a different mass number.
For example, carbon-12, carbon-13, and carbon-14 are three isotopes of the element carbon with mass numbers 12, 13, and 14, respectively. The atomic number of carbon is 6, which means that every carbon atom has 6 protons so that the neutron numbers of these isotopes are 6, 7, and 8 respectively.

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  1. B

    A Isotope dependence of Dunham Parameters

    Hello! I know that there is the famous Dunham parameterization of ro-vibrational levels of a diatomic molecule and later Watson wrote a paper deriving the isotopic dependence of these parameters. However, from what I found online this is only valid for a ##^{1}\Lambda## state. Is there a similar...
  2. M

    Hypothetical stable isotope of Promethium?

    Say one was to create an artificial stable isotope of Promethium as it has predicted applicable properties. What would it’s number have to be? I know Promethium-147 is semi-stable.
  3. A

    I Energy reduction/deflection of beta particles due to isotope geometry

    Hello all. I'm an undergraduate student looking to conduct an experiment with an isotope that undergoes beta decay. I am curious as to the degree to which the isotope geometry will reduce the energy of/deflect beta particles emitted from the isotope. By geometry, I mean the "shape" of the...
  4. B

    I Isotope measurements in molecules

    Hello! Is there any measurement (can be from different papers/experiments) of a diatomic molecular isotopic chain (i.e. at least 3 isotopes of a given nucleus) where the ground state is ##^{2}\Sigma##?
  5. M

    A How to simulate an isotope shift measurement

    Hello! My questions are based on this paper talking about King plot non-linearities. Assuming I have 3 isotopes and 2 transitions, I would like to know how well I should measure the transitions (i.e. what uncertainty on the transition value) in order to reach a given sensitivity for the new...
  6. P

    Is K41 more valuable than other isotopes of potassium?

    Can anyone tell me what the commonly used methods of isotope separation are for Potassium 41? I know there are many different methods used for isotope separation, but I'm wondering which method is most practical (cheapest and purity) in the case of potassium, specifically K41. Also roughly what...
  7. K

    I Spin-Orbit Coupling & Isotope Shift

    Hello! The isotope shift for an atomic transition is usually parameterized as: $$\delta\nu = K\frac{m_1m_2}{m_1-m_2}+F\delta<r^2>$$ where ##m_{1,2}## are the masses of the 2 isotopes, ##\delta<r^2>## is the change in the mean square charge radius between the 2 isotopes and K and F are some...
  8. K

    I Nuclear size effect on isotope shift

    Hello! The transition wavelength between 2 energy levels for an atom depends on the nuclear isotope through the mass of the isotope and the size of the nucleus. My question is only about the nuclear size effect. It can be shown that this effect can be written as (this is basically a taylor...
  9. S

    I What is theoretically the heaviest isotope that the R-process could produce?

    AIUI, the R-process in a supernova creates all the heavy isotopes, and that the existence of Pu-244 in the early solar system has been confirmed. It has been stated at the physics stack exchange forum that the theoretically shortest half-life possible is ~ 3 x 10-24 seconds, so let's consider...
  10. greg_rack

    Isotope decay via alpha and beta particle emissions

    This problem really confused me, since I can't get the link between particles emitted(alpha and beta, but which are the differences between those?) and changes in mass and atomic number of the isotope. For this one, I can't really show you my attempt since there ain't one...
  11. Astronuc

    B What is the significance of the newly discovered isotope, Mendelevium-244?

    A team of scientists working at Lawrence Berkeley National Laboratory (Berkeley Lab) has discovered a new form of the human-made element mendelevium. The newly created isotope, mendelevium-244, is the 17th and lightest form of mendelevium, which is element Z=101 on the periodic table...
  12. T

    What I do not understand about mass spectrometers

    I try to do my assignment which is based on mass spectrometer entirely. The mass spectrometer i am working on has these parts below: 1.Accelerator region 2.Velocity selector region 3.Spectrometer The elements i am working on are isotopes of the same element and they all enter the accelerator...
  13. K

    I Is the Isotope Shift the Same for Different Vibrational Levels in Molecules?

    Hello! Is the isotope shift between 2 (low lying) vibrational levels of the lowest 2 electronic levels (of a diatomic molecule) the same, no matter what the 2 levels are? For example, is the isotope shift associated to the ##0 \to 0## vibrational transition of 2 molecular isotopes (here I mean...
  14. S

    B How does one change the isotope of an element?

    Sorry if this is the wrong subforum i am new here How could one turn Palladium-102 into palladium-103? Would you take a cyclotron and hit it with neutrons? Or would you take Rhodium-103 and hit it with protons? The only reason I ask is because it has a half life of 17 days, and because of that...
  15. M

    B When does an isotope begin to decay?

    Take 60Fe found in meteorites. Does it start to decay the moment it is created. Or does it start to decay when it cools to a solid (a meteorite)? Does heat have anything to do with it? Thanks
  16. S

    I Isotope clock reset debunks earth's age?

    << Mentor Note -- typo fixed below with strikethrough history shown >> I am in a heated debate with a client climate change denier (he created some of the software for their instruments, he says all evidence of how Earth's age is determined is flawed because the Earth's crust is continually...
  17. Javier Lopez

    I Why there is a general lack of neutrons in the Earth?

    I where looking for elements that can absorpt neutrons without generating radioactive materials, and I found that most of them in Earth are suitable. I found that could work: C, O, Si, S, N, H The most common isotopes can receive one or two neutrons being stable, but if a neutron would be...
  18. S

    B Is 3-point of H20 used for Kelvin a certain set of isotope

    If I had had enough space to enter the proper question, it would have been: Is the triple point of water which is used for the definition of the unit of Kelvin defined as water having a certain isotopes such as 2 Hydrogen-1 & 1 Oxygen-16? Or would the error introduced by using different...
  19. M

    I Measured Isotope Masses: Exploring the Mass Excess

    Has anyone listed the actual experimentally measured masses of isotopes ? I find only the mass excesses listed. Why?
  20. prashantakerkar

    Isotope applications in Agriculture industry

    https://en.m.wikipedia.org/wiki/Isotope Can Isotopes be useful to Agriculture industry viz Fertilizers & Instecticides manufacturing? Thanks & Regards, Prashant S Akerkar
  21. opus

    Isotope word question clarification

    Homework Statement This is a multiple choice question. I have uploaded a screenshot of the question for reference. The atomic mass for a particular isotope of an element will: a) Always be equal to the value obtained by summing the masses of the protons and neutrons present in the atom. b)...
  22. C

    I Activity of daugther isotope in secular equilibrium

    Consider chain of two radioactive decays ##A \to B\to C##. The equation that regulates ##N_B## is $${\frac {\mathrm {d} N_{B}}{\mathrm {d} t}}=-\lambda _{B}N_{B}+\lambda _{A}N_{A}$$ I can't understand why the activity of ##B## is get as ##\lambda_B N_B##, for example at page 20 here...
  23. bland

    I Does quantum physics predict all isotope decays

    I am particularly wondering about zircon, element 40. I notice that its isotopes decay by either electron emission positron emission or electron capture, and I was curious to know whether this is established experimentally or if quantum physics is able to predict which isotopes will decay via...
  24. axer

    How to find an isotope given mass number and neutrons?

    Homework Statement An isotope of which element has a mass number of 111 and has 5 more neutrons A- Antimonu B- Cadmium C- Iodine D- Tin E- Xenon Homework EquationsThe Attempt at a Solution I don't know where to start
  25. S

    Maximizing Am242m Production from Spent Fuel for RTG Use

    I am wondering if anyone has considered this could be used in RTG's? To make Am242m one needs spent fuel that's been sitting around for a while, this has let the Pu241 decay to Am241. The question is, once you separate Am-241, can you run the reactor to favor Am242m production? Am242m is the...
  26. S

    I Is there no stable isotope of Tungsten?

    I was looking at this neat graph of all the isotopes and which ones are stable and how they decay: https://upload.wikimedia.org/wikipedia/commons/thumb/c/c4/Table_isotopes_en.svg/715px-Table_isotopes_en.svg.png The black squares represent stable isotopes, and columns that have no such black...
  27. ORF

    Detailed history about the discovery of "isotopes"?

    Hello I would like to know more about the history of the discovery of the isotopes, what there was before, and the short term impact on the chemistry and nuclear physics. Is this topic discussed in any book/review? Thank you for your time. Regards, ORF
  28. ORF

    Biochemist -- Is isotope ratio unique for each trophic level?

    Hello As far as I know, the reaction velocity depends on the isotope ("kinetic isotope effect"). So, is the isotope ratio (for example, for Nitrogen or Carbon isotopes) dependent on the trophic level? Thank you for your time. Regards, Alvaro.
  29. T

    B How are initial radioactive isotope quantities assumed?

    I'm stuck on this idea. How are initial radioactive isotope quantities assumed in radiometric dating? There are current abundances for all isotopes, but wouldn't these abundances have been different in the past (much higher)? I honestly can't grasp how radioactive isotopes with short half lives...
  30. C

    B Calculating heat from decay of a radioactive isotope

    How would one go about determining the amount of heat generated by the decay of a radioactive particle, such as Cesium 137, Polonium 210, or Strontium 90? How would you determine how much of the radioactive material would be needed to heat, say, a cup of water to a certain temperature, taking...
  31. moenste

    KE of alpha particle using integer values of nuclear masses

    Homework Statement (a) Cobalt has only one stable isotope, 59Co. What form of radioactive decay would you expect the isotope 60Co to undergo? Give a reason for your answer. (b) The radioactive nuclei 21084Po emit alpha particles of a single energy, the product nuclei being 20682Pb. (b) (i)...
  32. moenste

    Minimum safe distance from a radioactive source

    Homework Statement The potassium isotope 4219K has a half-life of 12 hr, and disintegrates with the emission of a γ-ray to form the calcium isotope 4220Ca. What other radiation besides γ-rays must be emitted? How many electrons, protons, and neutrons are there in an atom of the calcium isotope...
  33. Vitani11

    Direction of alpha particles/protons from isotope decay

    Homework Statement A stationary B nucleus decays into two alpha particles and a proton, and the speed of the proton is found to be 6.0x10^6 m/s. What is the magnitude and direction of the velocities of the alpha particles with respect to the proton? Homework Equations Unnecessary The Attempt...
  34. T

    B Does having more neutrons in an isotope make it more or les stable?

    Does more neutrons in an isotope make it more or less stable? I got two contradicting sources. I am also quite confused overall about the whole isotope business. The definition of an isotope is that it is an atom with the same number of protons but different number of neutrons. For example...
  35. M

    Wavenumber of corresponding isotope peak in IR?

    Homework Statement The infrared spectrum of CO shows a vibrational absorption peak at 2170 cm-1 (a) What is the force constant of the CO bond? (b) At what wavenumber would the corresponding peak for 14CO occur? Homework Equations k=ω2μ = (2πcv)2μThe Attempt at a Solution So I solved part a...
  36. Garlic

    Different stable nuclear spins for the same isotope

    Hello everyone, When I look at the isotope lists, I always see only one nuclear spin for a specific isotope. (Why) can't an isotope have different nuclear spin types that are stable? I know metastable isotopes exist, but I am asking about the stable isotopes. Can't there be a case where the...
  37. G

    How Do Isotope Tracers Determine Mixing Ratios in Water Samples?

    Homework Statement Two water samples are mixed. Sample 1 has δ18O-H2O = -1(per mil), Sample 2 has δ18O-H2O = -20 (per mil), and the mixture has δ18O-H2O = -15 (per mil). What fraction of water came from sample 1 and what fraction came from sample 2? Assume that F = the fraction of the water...
  38. HanningWu

    Why use mercury to verify isotope effect in superconducting?

    Because mercury has a low melting point? What are the advantages of mercury in the isotope effect experiment? Can we use some other materials?
  39. ScepticAmatuer

    H2O, HDO, D2O equilibrium concentrations

    I have seen something to this effect stated dozens of times on the internet : "..because the deuterons and the protons are exchanging so quickly, you will end up with a statistical distribution: 25% H2O, 25% D2O, and 50% HDO." They are referring to a sample of water which is 50 atom %...
  40. S

    Calculating Initial Decay Rate of Ga-67 Isotope

    Homework Statement An initially pure 3.4 g sample of Ga-67, an isotope with a half life of 78 hr. What is its initial decay rate? Note: Molar Mass values given in tables for chemical elements are for natural mix isotopic ratios. (i.e. the relative percentages of each isotope normally present...
  41. P

    Oscillating Isotopes: Semi-Stable/Stable Fission/Fusion?

    Are there any semi-stable or stable isotopes that can be made to oscillate between their self and their decay products? Specifically some kind of fission/fusion reaction where the decay is easily reversed with something like pressure (assuming the reversal is quick enough that the majority of...
  42. V

    What exactly does it mean for an isotope to be stable?

    The basic "nuclear physics for dummies" explanation of nuclear physics goes something like this: There are two dominant forces at play in atomic nuclei: the residual strong force (aka the nuclear force) which binds nucleons together and the electromagnetic force (or, more simply, the...
  43. Teemo

    Radioactive Decay to a Non-radioactive Isotope

    Homework Statement Magnesium (Z = 12) has isotopes that range from Mg–20 to Mg–31. Only Mg–24, Mg–25, and Mg–26 are not radioactive. What mode of radioactive decay would convert Mg–20, Mg–21, Mg–22, and Mg–23 into stable isotopes most quickly? (A) electron emission (B) alpha particle emission...
  44. M

    Uncovering Half-Life Data for Odd Isotopes: A Search for Fission Products

    The Sigma database at Brookhaven lists seven isotopes as fission products for which I can't find half-life data. I've tried nea6287-JEFF-20-1, the NuDat_2 web site, Nuclear Wallet Cards and Wikipedia. Anybody have any other ideas? The isotopes are 74-As-m1 85-Se-m1 86-Br-m1 109-Ru-m1...
  45. D

    Level After Decay of Radioactive Isotope

    Hello! So I have an issue with determining the probability of a daughter isotope's nucleus being on a certain level after decay from an unstable parent isotope's nucleus on another level. For example: I have a Co-60 nucleus and it decays to a Ni-60 nucleus by B- emission. If the parent Co-60...
  46. B

    Isotope halflife table by progamming

    i wan to do the folowimg : [ 1 ] use the computer to find halftimes of isotoops that are jet unkown [ 2 ] i want to use genetic programming [ 3 ] i use the idea that there is a function = halftime( protons , neutrons ) i have questions : - is [ 1 ][ 2 ] a good idea - i don't know if...
  47. E

    Activity of Isotope: mCi, mR, Rem Value & Distance

    Hi all, how can I find the activity of isotope which it has in area given value mCi or mR or Rem value of this? ionization energy of isotope how many distance can it travel on air and in earth-ground when I know only the Curi or Rem or Roengen? ex. Who they calculate the...
  48. K

    Why are exited states of an Isotope metastable?

    Why are exited states of an Isotope metastable? Is it because they have a large spin and therefore the final states they decay to have to be excited as well? And therefore they have less energy gain? I am thinking about 116 In (the 1+ and 5+ state) both can undergo a β- decay. Thank you!
  49. M

    What defines the kind of decay an isotope would go for?

    first, is my initial understanding correct that each isotope go for only a particular kind of decay? and if so, why? What makes uranium-238 go only for an alpha decay? while uranium 235 go for a fission decay?
  50. P

    Isotope fractionation with condensation

    Homework Statement I'm really confused about this concept. I know that when you evaporate a liquid, heavier isotopes stay behind because it's easier to evaporate lighter isotopes. This is intuitive to me. I'm confused on the case of condensation because I'm reading two things that seem...