Isotopes of mendelevium
Encyclopedia
Mendelevium
(Md) is an artificial element, and thus a standard atomic mass
cannot be given. Like all artificial elements, it has no stable isotope
s. The first isotope
to be synthesized was 256Md (which was also the first isotope of any element produced one atom
at a time) in 1955. There are 18 known radioisotopes, ranging in atomic mass
from 245Md to 262Md, and 5 isomer
s. The longest-lived isotope is 258Md with a half-life
of 51.3 days, and the longest-lived isomer is 258mMd with a half-life of 58.0 minutes.
Mendelevium
Mendelevium is a synthetic element with the symbol Md and the atomic number 101. A metallic radioactive transuranic element in the actinide series, mendelevium is usually synthesized by bombarding einsteinium with alpha particles. It was named after Dmitri Ivanovich Mendeleev, who created the...
(Md) is an artificial element, and thus a standard atomic mass
Atomic mass
The atomic mass is the mass of a specific isotope, most often expressed in unified atomic mass units. The atomic mass is the total mass of protons, neutrons and electrons in a single atom....
cannot be given. Like all artificial elements, it has no stable isotope
Stable isotope
Stable isotopes are chemical isotopes that may or may not be radioactive, but if radioactive, have half-lives too long to be measured.Only 90 nuclides from the first 40 elements are energetically stable to any kind of decay save proton decay, in theory...
s. The first 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...
to be synthesized was 256Md (which was also the first isotope of any element produced one atom
Atom
The atom is a basic unit of matter that consists of a dense central nucleus surrounded by a cloud of negatively charged electrons. The atomic nucleus contains a mix of positively charged protons and electrically neutral neutrons...
at a time) in 1955. There are 18 known radioisotopes, ranging in atomic mass
Atomic mass
The atomic mass is the mass of a specific isotope, most often expressed in unified atomic mass units. The atomic mass is the total mass of protons, neutrons and electrons in a single atom....
from 245Md to 262Md, and 5 isomer
Nuclear isomer
A nuclear isomer is a metastable state of an atomic nucleus caused by the excitation of one or more of its nucleons . "Metastable" refers to the fact that these excited states have half-lives more than 100 to 1000 times the half-lives of the other possible excited nuclear states...
s. The longest-lived isotope is 258Md 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 51.3 days, and the longest-lived isomer is 258mMd with a half-life of 58.0 minutes.
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.... SF: Spontaneous fission Spontaneous fission Spontaneous fission is a form of radioactive decay characteristic of very heavy isotopes. Because the nuclear binding energy reaches a maximum at a nuclear mass greater than about 60 atomic mass units , spontaneous breakdown into smaller nuclei and single particles becomes possible at heavier masses... |
daughter isotope(s) |
nuclear spin |
|---|---|---|---|---|---|---|---|
| excitation energy | |||||||
| 245Md | 101 | 144 | 245.08083(35)# | 0.90(25) ms | SF Spontaneous fission Spontaneous fission is a form of radioactive decay characteristic of very heavy isotopes. Because the nuclear binding energy reaches a maximum at a nuclear mass greater than about 60 atomic mass units , spontaneous breakdown into smaller nuclei and single particles becomes possible at heavier masses... |
(various) | (1/2-)# |
| 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... (rare) |
241Es | ||||||
| 245mMd | 200(100)# keV | 400(200) ms [0.35(+23-16) s] |
α | 241Es | (7/2+) | ||
| 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... (rare) |
245Fm | ||||||
| 246Md | 101 | 145 | 246.08189(35)# | 1.0(4) s | α | 242Es | |
| β+ (rare) | 246Fm | ||||||
| 247Md | 101 | 146 | 247.08164(35)# | 1.12(22) s | SF | (various) | 1/2-# |
| α (rare) | 243Es | ||||||
| 247mMd | ~0.2 s | α (99.99%) | 243Es | ||||
| SF (10−4%) | (various) | ||||||
| 248Md | 101 | 147 | 248.08282(26)# | 7(3) s | β+ (80%) | 248Fm | |
| α (20%) | 244Es | ||||||
| β+, SF (.05%) | (various) | ||||||
| 249Md | 101 | 148 | 249.08301(24)# | 24(4) s | α (60%) | 245Es | (7/2-) |
| β+ (40%) | 249Fm | ||||||
| 249mMd | 100(100)# keV | 1.9(9) s | (1/2-) | ||||
| 250Md | 101 | 149 | 250.08442(32)# | 52(6) s | β+ (93%) | 250Fm | |
| α (7%) | 246Es | ||||||
| β+, SF (.02%) | (various) | ||||||
| 251Md | 101 | 150 | 251.08484(22)# | 4.0(5) min | β+ (90%) | 251Fm | 7/2-# |
| α (10%) | 247Es | ||||||
| 252Md | 101 | 151 | 252.08656(21)# | 2.3(8) min | β+ (50%) | 252Fm | |
| α (50%) | 248Es | ||||||
| 253Md | 101 | 152 | 253.08728(22)# | 12(8) min [6(+12-3) min] |
β+ | 253Fm | 7/2-# |
| α | 249Es | ||||||
| 254Md | 101 | 153 | 254.08966(11)# | 10(3) min | β+ | 254Fm | (0-) |
| α (rare) | 250Es | ||||||
| 254mMd | 50(100)# keV | 28(8) min | β+ | 254Fm | (3-) | ||
| α (rare) | 250Es | ||||||
| 255Md | 101 | 154 | 255.091083(7) | 27(2) min | β+ (92%) | 255Fm | (7/2-) |
| α (8%) | 251Es | ||||||
| SF (.15%) | (various) | ||||||
| 256Md | 101 | 155 | 256.09406(6) | 77(2) min | β+ (89%) | 256Fm | (1-) |
| α (11%) | 252Es | ||||||
| 257Md | 101 | 156 | 257.095541(3) | 5.52(5) h | EC Electron capture Electron capture is a process in which a proton-rich nuclide absorbs an inner atomic electron and simultaneously emits a neutrino... (84.8%) |
257Fm | (7/2-) |
| α (15.2%) | 253Es | ||||||
| SF (1%) | (various) | ||||||
| 258Md | 101 | 157 | 258.098431(5) | 51.5(3) d | α (99.99%) | 254Es | (8-)# |
| β- (.0015%) | 258No | ||||||
| β+ (.0015%) | 258Fm | ||||||
| 258mMd | 0(200)# keV | 57.0(9) min | EC (70%) | 258Fm | 1-# | ||
| SF (20%) | (various) | ||||||
| β- (10%) | 258No | ||||||
| α (1.2%) | 254Es | ||||||
| 259Md | 101 | 158 | 259.10051(22)# | 1.60(6) h | SF (98.7%) | (various) | 7/2-# |
| α (1.3%) | 255Es | ||||||
| 260Md | 101 | 159 | 260.10365(34)# | 27.8(8) d | SF (85%) | (various) | |
| α (5%) | 256Es | ||||||
| EC (5%) | 260Fm | ||||||
| β- (3.5%) | 260No | ||||||
| 261Md | 101 | 160 | 261.10572(70)# | 40# min | 7/2-# | ||
| 262Md | 101 | 161 | 262.10887(63)# | 3# min | |||