Isotopes of chromium
Encyclopedia
Naturally occurring chromium
(Cr) is composed of four stable isotope
s; 50Cr, 52Cr, 53Cr, and 54Cr with 52Cr being the most abundant (83.789% natural abundance
). 50Cr is suspected of decaying by β+β+
to 50Ti with a half-life
of (more than) 1.8x1017 years. Twenty-two radioisotopes, all which are entirely synthetic, have been characterized with the most stable being 51Cr with a half-life of 27.7 days. All of the remaining radioactive isotopes have half-lives that are less than 24 hours and the majority of these have half-lives that are less than 1 minute, the least stable being 66Cr with a half-life of 10 milliseconds. This element also has 2 meta states, 45Crm, the more stable one, and 59Crm, the least stable isotope or isomer.
53Cr is the radiogenic decay product of 53Mn
. Chromium isotopic
contents are typically combined with manganese
isotopic contents and have found application in isotope geology. Mn
-Cr isotope ratios reinforce the evidence from 26Al
and 107Pd
for the early history of the solar system
. Variations in 53Cr/52Cr and Mn/Cr ratios from several meteorites indicate an initial 53Mn/55Mn ratio that suggests Mn-Cr isotope systematics must result from in-situ decay of 53Mn in differentiated planetary bodies. Hence 53Cr provides additional evidence for nucleosynthetic
processes immediately before coalescence of the solar system. The same isotope is preferentially involved in certain leaching reactions, thereby allowing its abundance in seawater sediments to be used as a proxy for atmospheric oxygen concentrations.
The isotopes of chromium range from 42Cr to 67Cr. The primary decay mode before the most abundant stable isotope, 52Cr, is electron capture
and the primary mode after is beta decay
.
Standard atomic mass: 51.9961(6) u
The atomic mass is originally 53 but as an isotope rounded to the nearest tenth is 52.
Chromium
Chromium is a chemical element which has the symbol Cr and atomic number 24. It is the first element in Group 6. It is a steely-gray, lustrous, hard metal that takes a high polish and has a high melting point. It is also odorless, tasteless, and malleable...
(Cr) is composed of four stable isotope
Isotope
Isotopes are variants of atoms of a particular chemical element, which have differing numbers of neutrons. Atoms of a particular element by definition must contain the same number of protons but may have a distinct number of neutrons which differs from atom to atom, without changing the designation...
s; 50Cr, 52Cr, 53Cr, and 54Cr with 52Cr being the most abundant (83.789% natural abundance
Natural abundance
In chemistry, natural abundance refers to the abundance of isotopes of a chemical element as naturally found on a planet. The relative atomic mass of these isotopes is the atomic weight listed for the element in the periodic table...
). 50Cr is suspected of decaying by β+β+
Double beta decay
Double beta decay is a radioactive decay process where a nucleus releases two beta rays as a single process.In double-beta decay, two neutrons in the nucleus are converted to protons, and two electrons and two electron antineutrinos are emitted...
to 50Ti with a half-life
Half-life
Half-life, abbreviated t½, is the period of time it takes for the amount of a substance undergoing decay to decrease by half. The name was originally used to describe a characteristic of unstable atoms , but it may apply to any quantity which follows a set-rate decay.The original term, dating to...
of (more than) 1.8x1017 years. Twenty-two radioisotopes, all which are entirely synthetic, have been characterized with the most stable being 51Cr with a half-life of 27.7 days. All of the remaining radioactive isotopes have half-lives that are less than 24 hours and the majority of these have half-lives that are less than 1 minute, the least stable being 66Cr with a half-life of 10 milliseconds. This element also has 2 meta states, 45Crm, the more stable one, and 59Crm, the least stable isotope or isomer.
53Cr is the radiogenic decay product of 53Mn
Manganese
Manganese is a chemical element, designated by the symbol Mn. It has the atomic number 25. It is found as a free element in nature , and in many minerals...
. Chromium isotopic
Isotope
Isotopes are variants of atoms of a particular chemical element, which have differing numbers of neutrons. Atoms of a particular element by definition must contain the same number of protons but may have a distinct number of neutrons which differs from atom to atom, without changing the designation...
contents are typically combined with manganese
Manganese
Manganese is a chemical element, designated by the symbol Mn. It has the atomic number 25. It is found as a free element in nature , and in many minerals...
isotopic contents and have found application in isotope geology. Mn
Manganese
Manganese is a chemical element, designated by the symbol Mn. It has the atomic number 25. It is found as a free element in nature , and in many minerals...
-Cr isotope ratios reinforce the evidence from 26Al
Aluminium
Aluminium or aluminum is a silvery white member of the boron group of chemical elements. It has the symbol Al, and its atomic number is 13. It is not soluble in water under normal circumstances....
and 107Pd
Palladium
Palladium is a chemical element with the chemical symbol Pd and an atomic number of 46. It is a rare and lustrous silvery-white metal discovered in 1803 by William Hyde Wollaston. He named it after the asteroid Pallas, which was itself named after the epithet of the Greek goddess Athena, acquired...
for the early history of the solar system
Solar System
The Solar System consists of the Sun and the astronomical objects gravitationally bound in orbit around it, all of which formed from the collapse of a giant molecular cloud approximately 4.6 billion years ago. The vast majority of the system's mass is in the Sun...
. Variations in 53Cr/52Cr and Mn/Cr ratios from several meteorites indicate an initial 53Mn/55Mn ratio that suggests Mn-Cr isotope systematics must result from in-situ decay of 53Mn in differentiated planetary bodies. Hence 53Cr provides additional evidence for nucleosynthetic
Nucleosynthesis
Nucleosynthesis is the process of creating new atomic nuclei from pre-existing nucleons . It is thought that the primordial nucleons themselves were formed from the quark–gluon plasma from the Big Bang as it cooled below two trillion degrees...
processes immediately before coalescence of the solar system. The same isotope is preferentially involved in certain leaching reactions, thereby allowing its abundance in seawater sediments to be used as a proxy for atmospheric oxygen concentrations.
The isotopes of chromium range from 42Cr to 67Cr. The primary decay mode before the most abundant stable isotope, 52Cr, is electron capture
Electron capture
Electron capture is a process in which a proton-rich nuclide absorbs an inner atomic electron and simultaneously emits a neutrino...
and the primary mode after is beta decay
Beta decay
In nuclear physics, beta decay is a type of radioactive decay in which a beta particle is emitted from an atom. There are two types of beta decay: beta minus and beta plus. In the case of beta decay that produces an electron emission, it is referred to as beta minus , while in the case of a...
.
Standard atomic mass: 51.9961(6) u
The atomic mass is originally 53 but as an isotope rounded to the nearest tenth is 52.
Table
| nuclide symbol |
Z(p Proton The proton is a subatomic particle with the symbol or and a positive electric charge of 1 elementary charge. One or more protons are present in the nucleus of each atom, along with neutrons. The number of protons in each atom is its atomic number.... ) |
N(n Neutron The neutron is a subatomic hadron particle which has the symbol or , no net electric charge and a mass slightly larger than that of a proton. With the exception of hydrogen, nuclei of atoms consist of protons and neutrons, which are therefore collectively referred to as nucleons. The number of... ) |
isotopic mass (u) |
half-life | decay mode(s)Abbreviations: EC: Electron capture Electron capture Electron capture is a process in which a proton-rich nuclide absorbs an inner atomic electron and simultaneously emits a neutrino... IT: Isomeric transition Isomeric transition An isomeric transition is a radioactive decay process that involves emission of a gamma ray from an atom where the nucleus is in an excited metastable state, referred to in its excited state, as a nuclear isomer.... |
daughter isotope(s)Bold for stable isotopes |
nuclear spin |
representative isotopic composition (mole fraction) |
range of natural variation (mole fraction) |
|---|---|---|---|---|---|---|---|---|---|
| excitation energy | |||||||||
| 42Cr | 24 | 18 | 42.00643(32)# | 14(3) ms [13(+4-2) ms] |
β+ Beta decay In nuclear physics, beta decay is a type of radioactive decay in which a beta particle is emitted from an atom. There are two types of beta decay: beta minus and beta plus. In the case of beta decay that produces an electron emission, it is referred to as beta minus , while in the case of a... (>99.9%) |
42V | 0+ | ||
| 2p Proton emission Proton emission is a type of radioactive decay in which a proton is ejected from a nucleus. Proton emission can occur from high-lying excited states in a nucleus following a beta decay, in which case the process is known as beta-delayed proton emission, or can occur from the ground state of very... (<.1%) |
40Ti | ||||||||
| 43Cr | 24 | 19 | 42.99771(24)# | 21.6(7) ms | β+ (71%) | 43V | (3/2+) | ||
| β+, p (23%) | 42Ti | ||||||||
| β+, 2p (6%) | 41Sc | ||||||||
| β+, α Alpha decay Alpha decay is a type of radioactive decay in which an atomic nucleus emits an alpha particle and thereby transforms into an atom with a mass number 4 less and atomic number 2 less... (<.1%) |
39Sc | ||||||||
| 44Cr | 24 | 20 | 43.98555(5)# | 54(4) ms [53(+4-3) ms] |
β+ (93%) | 44V | 0+ | ||
| β+, p (7%) | 43Ti | ||||||||
| 45Cr | 24 | 21 | 44.97964(54) | 50(6) ms | β+ (73%) | 45V | 7/2-# | ||
| β+, p (27%) | 44Ti | ||||||||
| 45mCr | 50(100)# keV | 1# ms | IT Isomeric transition An isomeric transition is a radioactive decay process that involves emission of a gamma ray from an atom where the nucleus is in an excited metastable state, referred to in its excited state, as a nuclear isomer.... |
45Cr | 3/2+# | ||||
| β+ | 45V | ||||||||
| 46Cr | 24 | 22 | 45.968359(21) | 0.26(6) s | β+ | 46V | 0+ | ||
| 47Cr | 24 | 23 | 46.962900(15) | 500(15) ms | β+ | 47V | 3/2- | ||
| 48Cr | 24 | 24 | 47.954032(8) | 21.56(3) h | β+ | 48V | 0+ | ||
| 49Cr | 24 | 25 | 48.9513357(26) | 42.3(1) min | β+ | 49V | 5/2- | ||
| 50Cr | 24 | 26 | 49.9460442(11) | Observationally StableSuspected of decaying by β+β+ decay to 50Ti with a half-life of no less than 1.3 a | 0+ | 0.04345(13) | 0.04294-0.04345 | ||
| 51Cr | 24 | 27 | 50.9447674(11) | 27.7025(24) d | EC Electron capture Electron capture is a process in which a proton-rich nuclide absorbs an inner atomic electron and simultaneously emits a neutrino... |
51V | 7/2- | ||
| 52Cr | 24 | 28 | 51.9405075(8) | Stable | 0+ | 0.83789(18) | 0.83762-0.83790 | ||
| 53Cr | 24 | 29 | 52.9406494(8) | Stable | 3/2- | 0.09501(17) | 0.09501-0.09553 | ||
| 54Cr | 24 | 30 | 53.9388804(8) | Stable | 0+ | 0.02365(7) | 0.02365-0.02391 | ||
| 55Cr | 24 | 31 | 54.9408397(8) | 3.497(3) min | β- | 55Mn | 3/2- | ||
| 56Cr | 24 | 32 | 55.9406531(20) | 5.94(10) min | β- | 56Mn | 0+ | ||
| 57Cr | 24 | 33 | 56.943613(2) | 21.1(10) s | β- | 57Mn | (3/2-) | ||
| 58Cr | 24 | 34 | 57.94435(22) | 7.0(3) s | β- | 58Mn | 0+ | ||
| 59Cr | 24 | 35 | 58.94859(26) | 460(50) ms | β- | 59Mn | 5/2-# | ||
| 59mCr | 503.0(17) keV | 96(20) µs | (9/2+) | ||||||
| 60Cr | 24 | 36 | 59.95008(23) | 560(60) ms | β- | 60Mn | 0+ | ||
| 61Cr | 24 | 37 | 60.95472(27) | 261(15) ms | β- (>99.9%) | 61Mn | 5/2-# | ||
| β-, n Neutron emission Neutron emission is a type of radioactive decay of atoms containing excess neutrons, in which a neutron is simply ejected from the nucleus. Two examples of isotopes which emit neutrons are helium-5 and beryllium-13... (<.1%) |
60Mn | ||||||||
| 62Cr | 24 | 38 | 61.95661(36) | 199(9) ms | β- (>99.9%) | 62Mn | 0+ | ||
| β-, n | 61Mn | ||||||||
| 63Cr | 24 | 39 | 62.96186(32)# | 129(2) ms | β- | 63Mn | (1/2-)# | ||
| β-, n | 62Mn | ||||||||
| 64Cr | 24 | 40 | 63.96441(43)# | 43(1) ms | β- | 64Mn | 0+ | ||
| 65Cr | 24 | 41 | 64.97016(54)# | 27(3) ms | β- | 65Mn | (1/2-)# | ||
| 66Cr | 24 | 42 | 65.97338(64)# | 10(6) ms | β- | 66Mn | 0+ | ||
| 67Cr | 24 | 43 | 66.97955(75)# | 10# ms [>300 ns] |
β- | 67Mn | 1/2-# | ||