Naturally occurring iron (Fe) consists of four isotopes: 5.845% of ⁵⁴Fe (possibly radioactive with a half-life over 3.1×10²² years), 91.754% of ⁵⁶Fe, 2.119% of ⁵⁷Fe and 0.282% of ⁵⁸Fe. There are 24 known radioactive isotopes and their half-lives are shown below. See Brookhaven National Laboratory Interactive Table of Nuclides for a more accurate reading.

Much of the past work on measuring the isotopic composition of Fe has centered on determining ⁶⁰Fe variations due to processes accompanying nucleosynthesis (i.e., meteorite studies) and ore formation. In the last decade however, advances in mass spectrometry technology have allowed the detection and quantification of minute, naturally occurring variations in the ratios of the stable isotopes of iron. Much of this work has been driven by the Earth and planetary science communities, although applications to biological and industrial systems are beginning to emerge.^[1]

Iron-54[link]

⁵⁴Fe is observationally stable, with a branching theory that it decays to ⁵⁴Cr, with a half-life of more than 3.1x10²² years via double electron capture (2β⁺). All other natural isotopes are known to be stable, which makes ⁵⁴Fe seemingly strange.

Iron-56[link]

The isotope ⁵⁶Fe is the isotope with the lowest mass per nucleon, 930.412 MeV/c², though not the isotope with the highest nuclear binding energy per nucleon, which is Nickel-62.^[2] However, because of the details of how nucleosynthesis works, ⁵⁶Fe is a more common endpoint of fusion chains inside extremely massive stars and is therefore more common in the universe, relative to other metals, including ⁶²Ni, ⁵⁸Fe and ⁶⁰Ni, all of which have a very high binding energy.

Iron-57[link]

The isotope ⁵⁷Fe is widely used in Mössbauer spectroscopy due to the low natural variation in energy of the 14.4keV nuclear transition.^[3]

Iron-60[link]

Iron-60 is another isotope. It has a half-life of 2.6 million years,^[4][5] but was thought until 2009 to have a half-life of 1.5 million years. It undergoes beta decay to cobalt-60.

In phases of the meteorites Semarkona and Chervony Kut a correlation between the concentration of ⁶⁰Ni, the granddaughter isotope of ⁶⁰Fe, and the abundance of the stable iron isotopes could be found which is evidence for the existence of ⁶⁰Fe at the time of formation of the solar system. Possibly the energy released by the decay of ⁶⁰Fe contributed, together with the energy released by decay of the radionuclide ²⁶Al, to the remelting and differentiation of asteroids after their formation 4.6 billion years ago. The abundance of ⁶⁰Ni present in extraterrestrial material may also provide further insight into the origin of the solar system and its early history.

Standard atomic mass: 55.845(2) u

Table[link]

1. ^ Abbreviations:
   EC: Electron capture
   IT: Isomeric transition
2. ^ Bold for stable isotopes
3. ^ Believed to decay by β⁺β⁺ to ⁵⁴Cr with a half-life of over 3.1×10²² a
4. ^ Lowest mass per nucleon of all nuclides; End product of stellar nucleosynthesis

Notes[link]

• Values marked # are not purely derived from experimental data, but at least partly from systematic trends. Spins with weak assignment arguments are enclosed in parentheses.
• Uncertainties are given in concise form in parentheses after the corresponding last digits. Uncertainty values denote one standard deviation, except isotopic composition and standard atomic mass from IUPAC which use expanded uncertainties.

See also[link]

• Iron-56

References[link]

• Isotope masses from:
  • G. Audi, A. H. Wapstra, C. Thibault, J. Blachot and O. Bersillon (2003). "The NUBASE evaluation of nuclear and decay properties". Nuclear Physics A 729: 3–128. Bibcode 2003NuPhA.729....3A. DOI:10.1016/j.nuclphysa.2003.11.001. http://www.nndc.bnl.gov/amdc/nubase/Nubase2003.pdf. 
• Isotopic compositions and standard atomic masses from:
  • J. R. de Laeter, J. K. Böhlke, P. De Bièvre, H. Hidaka, H. S. Peiser, K. J. R. Rosman and P. D. P. Taylor (2003). "Atomic weights of the elements. Review 2000 (IUPAC Technical Report)". Pure and Applied Chemistry 75 (6): 683–800. DOI:10.1351/pac200375060683. http://www.iupac.org/publications/pac/75/6/0683/pdf/. 
  • M. E. Wieser (2006). "Atomic weights of the elements 2005 (IUPAC Technical Report)". Pure and Applied Chemistry 78 (11): 2051–2066. DOI:10.1351/pac200678112051. http://iupac.org/publications/pac/78/11/2051/pdf/. Lay summary. 
• Half-life, spin, and isomer data selected from the following sources. See editing notes on this article's talk page.
  • G. Audi, A. H. Wapstra, C. Thibault, J. Blachot and O. Bersillon (2003). "The NUBASE evaluation of nuclear and decay properties". Nuclear Physics A 729: 3–128. Bibcode 2003NuPhA.729....3A. DOI:10.1016/j.nuclphysa.2003.11.001. http://www.nndc.bnl.gov/amdc/nubase/Nubase2003.pdf. 
  • National Nuclear Data Center. "NuDat 2.1 database". Brookhaven National Laboratory. http://www.nndc.bnl.gov/nudat2/. Retrieved September 2005. 
  • N. E. Holden (2004). "Table of the Isotopes". In D. R. Lide. CRC Handbook of Chemistry and Physics (85th ed.). CRC Press. Section 11. ISBN 978-0-8493-0485-9. 

Further reading[link]

• J. M. Nielsen (1960). The Radiochemistry of Iron. National Academy of Sciences/National Research Council. http://library.lanl.gov/cgi-bin/getfile?rc000015.pdf. 

Atom
Publication information
Publisher	DC Comics
First appearance	(Cray) Suicide Squad #44 (August 1990) (Atom One Million) DC One Million 80-Page Giant #1,000,000 (August 1999)
Created by	(Cray) John Ostrander (Atom One Million) Grant Morrison
In-story information
Alter ego	- Al Pratt - Ray Palmer - Adam Cray - Ryan Choi
Team affiliations	(Cray) Suicide Squad Black Lantern Corps (Atom One Million) Justice Legion Alpha
Abilities	(All-except Pratt and Atom One Million) Ability to shrink and grow his body to varying degrees (including the subatomic level) while manipulating his weight and mass to his advantage

The Atom is a name shared by several fictional comic book superheroes from the DC Comics universe.

There have been five characters who have shared the Atom codename. The original Golden Age Atom, Al Pratt, was created by Ben Flinton and Bill O'Connor and first appeared in All-American Publications' All-American Comics #19 (Oct. 1940). The second Atom was the Silver Age Atom, Ray Palmer, who first appeared in 1961. The third Atom, Adam Cray, was a minor character present in Suicide Squad stories. The fourth Atom, Ryan Choi, debuted in a new Atom series in August 2006. The fifth Atom from the 853rd Century first appeared as part of Justice Legion Alpha in August 1999.

The Atom has been the star of multiple solo series, and four of the five have appeared as members of various superhero teams, such as the Justice Society of America, the Justice League, the Suicide Squad, and the Justice Legion Alpha.

Fictional character biographies[link]

Al Pratt[link]

The original Atom, Al Pratt, first appeared in All-American Comics #19 (Oct. 1940). He initially had no superpowers; instead, he was a diminutive college student and later a physicist who was depicted as a tough guy, a symbol of all the short kids who could still make a difference. Pratt was a founding member of the Justice Society of America, later gaining limited super-strength, and an energy charged 'atomic punch'. He died in the charge against Extant during the Zero Hour.^[1]

Ray Palmer[link]

The Atom introduced during the Silver Age of comic books in Showcase #34 (1961) is physicist and university professor Ray Palmer (named for real-life science fiction writer Raymond A. Palmer, who was himself quite short). Using a mass of white dwarf star matter, he fashioned a lens which allowed him to shrink down to subatomic size. Originally, his size and molecular density abilities derived from the white dwarf star material of his costume, controlled by mechanisms in his belt, and later by controls in the palms of his gloves. Much later, he gained the innate equivalent powers within his own body. After the events of Identity Crisis, Ray shrunk himself to microscopic size and disappeared. Finding him became a major theme of the Countdown year long series and crossover event.^[1]

Paul Hoben[link]

Prior to Ray Palmer's fateful trip to the Amazon Jungle, he learns his wife Jean Loring had an affair with fellow lawyer Paul Hoben and the two divorce. Later, Palmer would offer his blessing to the couple who marry and offers Hoben his size-changing belt in order to protect Ivy Town (as Ray wished to remain with the Morlaidhans) which he accepts. His belt would later be stolen by Adam Cray. It should be noted, Hoben never takes up the costume or name of the Atom.

Adam Cray[link]

Adam Cray, son of the murdered Senator Cray, first appeared as the Atom in the pages of Suicide Squad #44 by John Ostrander (August 1990). At first Cray was widely believed to be Ray Palmer in disguise (by both the fans and the characters). Actually Cray had been recruited by Palmer himself, who faked his death, in order to apprehend the Micro Squad (a group of villains that had been shrunk down) as well as uncover information about a shadowy government cabal, who were interested in Palmer's knowledge of the other heroes' secret identities (his own identity being no longer a secret).

While Palmer would infiltrate the Micro Squad, Cray would gather the attention of the Cabal as the new Atom, so that no one would notice Palmer assuming the identity of a fallen Micro Squad member.

Adam Cray ran with the Suicide Squad only for a short while, serving as a secret weapon most of the time, and his existence was for a while even unknown to others of the Squad. Cray even saves a wounded Amanda Waller from a group of assassins. At one point, Cray approaches Deadshot about the fact that Deadshot had murdered his father. Deadshot tells Cray that he would get one free shot at him. Soon after, on a mission, Cray is impaled through the chest by Blacksnake, a Micro Squad member who believes him to be Palmer.

After the murder of Cray (a move Palmer had not foreseen), Palmer reveals himself and defeats Cray's murderer. The ruse ended, Palmer explains himself to the Justice League, who had been searching for him, after hearing rumors of a new Atom.

During the events of Blackest Night, Adam's corpse is reanimated as a member of the Black Lantern Corps alongside several other fallen Suicide Squad members.^[2] Following his reanimation, Adam and the other Black Lanterns travel to Belle Reve and attack Bane and Black Alice.^[3] Adam is apparently destroyed by the Manhunter's self destruct mechanism to unleashing an explosion of Green Lantern energy that eradicates the Black Lanterns.^[4]

Ryan Choi[link]

Ryan Choi, as described by DC solicitations, is "a young hotshot professor who's filling the extra spot on Ivy University's teaching staff. .. and who inadvertently ends up filling the old Atom's super-heroic shoes".^[5] This new Atom is based on a redesign by Grant Morrison. He debuted in the Brave New World one-shot, a preview of upcoming projects, and then appeared in the series, The All-New Atom, written by Gail Simone. He is later murdered by Deathstroke and his Titans.

Atom One Million[link]

An unnamed scientist in the 853rd Century performed experiments in superstring theory that creates a singularity and whose radiation alters his physical make-up. When the singularity threatened to expand and destroy his universe, he enters it in an attempt to save the universe but instead finds himself on an interdimensional bridge to another universe as his own is wiped out, unable to stop it. At the end of the bridge, he finds Superman Prime who came to help but was too late. Stranded, he searches this universe for remnants of the one he lost, in time taking the name the Atom and joining the Justice Legion Alpha when he helped them defeat the Bizarro-Legion. This Atom's powers differ from his predecessors in that he doesn't shrink but breaks up into several smaller duplicates of himself divided amongst his mass. At atomic size, these duplicates can mimic elements such as gold and oxygen.

Other versions[link]

Frank Miller portrayed Ray Palmer as a major player in Batman: The Dark Knight Strikes Again. He was taken prisoner by Lex Luthor and made to live in one of his own petri dishes for a period of months until his rescue by Catgirl. He was then instrumental in the liberation of Kandor.

Tangent Comics[link]

In the Tangent Comics print, The Atom is Arthur Harrison Thompson, a subject of radiation testing on human beings. The first hero in the Tangent timeline, he was succeeded by his son, who was killed by the Tangent Comics version of the Fatal Five, and a grandson named Adam, who, in Tangent: Superman's Reign, is being held captive by Superman.

Elseworlds[link]

• Some other re-imaginings of the Atom include an appearance in League of Justice, a story portraying the Justice League in a The Lord of the Rings-type story where the Atom was recast as a wizard/fortune teller called "Atomus The Palmer".

• Al Pratt as the Atom was one of the three heroes who chose to work at the side of Senator Thompson in The Golden Age. When Al discovers that Thompson is really the Ultra-Humanite, he joins the other heroes against the villain and Dyna-Man.

• The Al Pratt Atom appeared in JSA: The Unholy Three as a post-WW2 intelligence agent with transparent atomic flesh and a visible skeleton.

• JLA: Age of Wonder where Ray Palmer worked with a science consortium whose numbers at one point included Thomas Edison and Nikola Tesla.

• JLA: Created Equal, after Ray Palmer is killed in the cosmic storm that nearly wipes out the rest of the male population on Earth, a graduate student named Jill Athron is given a research grant to study Palmer's white-dwarf-star-belt. She becomes the Atom and joins the Justice League.

• Atom evolved from a hawkman that had evolved from Robin in the Just Imagine... comic book.^[6]

52 Multiverse[link]

In the final issue of 52, a new Multiverse is revealed, originally consisting of 52 identical realities. Among the parallel realities shown is one designated "Earth-2". As a result of Mister Mind "eating" aspects of this reality, it takes on visual aspects similar to the pre-Crisis Earth-2, including the Atom among other Justice Society of America characters. The names of the characters and the team are not mentioned in the panel in which they appear, but the Atom is visually similar to the Al Pratt Atom.^[7] Based on comments by Grant Morrison, this alternate universe is not the pre-Crisis Earth-2.^[8]

In Countdown #30, the Challengers from Beyond encountered Earth-15, a world where the sidekicks had taken their mentor's places. On this Earth, the Atom is Jessica Palmer, a genius who graduated from MIT at age eight. The Search for Ray Palmer - Red Son features the Ray Palmer of Earth-30, an American captured by the Superman of a communist Russia. Countdown: Arena also depicts the Ray Palmer of Earth-6, who through unknown circumstances now has the powers and title of the Ray. The Search For Ray Palmer: Superwoman/Batwoman briefly features a female version of The Atom.

In the first issue of the 2010 Batman Beyond limited series, a future African-American version of the Atom known as Micron appears as one of the heroes of Earth-12.

Collected Editions[link]

[edit] Ray Palmer

[edit] Ryan Choi

In other media[link]

Television[link]

• Ray Palmer (voiced by Pat Harrington, Jr.) appeared in his own episodes in The Superman/Aquaman Hour of Adventure.
• Ray Palmer appears with the SuperFriends in The All-New Super Friends Hour and The Super Friends Hour voiced by Wally Burr.
• The Atom also makes an appearance with a slightly different color scheme costume in the live action 1979 TV special "Legends of the Superheroes", specifically "The Roast" episode.
• A future version of the Atom called Micron appeared as a Justice League Unlimited member in the Batman Beyond two part episode "The Call" voiced by Wayne Brady. Unlike the Atom, Micron can grow as well as shrink, and similar to Atom Smasher with super-strength.
• In an early Justice League episode, "Legends," the League team up with the Justice Society pastiche the Justice Guild of America. JGA member Tom Turbine is a cross between Golden Age Atom and the Golden Age Superman^{[citation needed]}. The Atom is later mentioned by name in "Hereafter," as a future Vandal Savage describes how he stole technology from Ray Palmer and destroyed the world.
• The Atom (Ray Palmer) later appeared in Justice League Unlimited in both "Dark Heart" and "The Return" as a nanotechnology expert, voiced by John C. McGinley.
• The Atom (Ray Palmer) also appeared in the 1997 live action made-for-TV movie pilot, Justice League of America played by John Kassir.
• The Ryan Choi version of the Atom appears in the series Batman: The Brave and the Bold, voiced by James Sie. The Atom helps Batman stop evil sorcerer Felix Faust from opening Pandora's Box in "Evil Under the Sea!". He re-appeared along with Aquaman to save Batman from a virus created by Chemo in "Journey to the Center of the Bat!". Atom has a Crime Syndicate counterpart called Dyna-Mite, also voiced by James Sie. A mind-controlled Ryan Choi appears in "The Siege of Starro! Part One", demonstrating the ability to grow to giant sizes, which he uses to prevent Batman from destroying a signal leading Starro to Earth. He also appears in the teaser for "The Criss Cross Conspiracy!", where he, Batman, and Aquaman battle the Bug-Eyed Bandit.
• The Atom is briefly mentioned in the Young Justice episode "Failsafe", with Cat Grant stating that he had been killed alongside Batman, Icon and Aquaman during an alien invasion of Earth. The invasion is later revealed to simply be a training exercise. The Atom is shown among several candidates for Justice League membership in the episode "Agendas" where Batman cites his size-changing abilities as an important asset and he is officially inducted into the group in the episode "Usual Suspects".

Video Game[link]

• The Atom (Ray Palmer) appears in DC Universe Online.

See Also[link]

• Molecule

References[link]

External links[link]

• Index to the Atom's Earth-1 adventures
• Article on the history/legacy of The Atom from the Comics 101 article series by Scott Tipton
• THE SIMONE FILES II: THE ALL NEW ATOM
• COUNTING DOWN TO COUNTDOWN IV: THE GREAT DISASTER AND THE ATOM