Differences Between Hydrogen and Atomic Bombs

Hydrogen bomb explosion
Hydrogen bomb explosion.

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A hydrogen bomb and an atomic bomb are both types of nuclear weapons, but the two devices are very different from each other. In a nutshell, an atomic bomb is a fission device, while a hydrogen bomb uses fission to power a fusion reaction. In other words, an atomic bomb can be used as a trigger for a hydrogen bomb.

Take a look at the definition of each type of bomb and understand the distinction between them.

Atomic Bomb

An atomic bomb or A-bomb is a nuclear weapon that explodes due to the extreme energy released by nuclear fission. For this reason, this type of bomb is also known as a fission bomb. The word "atomic" isn't strictly accurate since it's just the nucleus of the atom that is involved in fission (its protons and neutrons), rather than the entire atom or its electrons.

A material capable of fission (fissile material) is given supercritical mass, while is the point at which fission occurs. This can be achieved by either compressing sub-critical material using explosives or by shooting one part of a sub-critical mass into another one. The fissile material is enriched uranium or plutonium. The energy output of the reaction can range to the equivalent of about a ton of the explosive TNT up to 500 kilotons of TNT. The bomb also releases radioactive fission fragments, which result from the heavy nuclei breaking into smaller ones. Nuclear fallout mainly consists of fission fragments.

Hydrogen Bomb

A hydrogen bomb or H-bomb is a type of nuclear weapon that explodes from the intense energy released by nuclear fusion. Hydrogen bombs may also be called thermonuclear weapons. The energy results from the fusion of isotopes of hydrogen—deuterium and tritium. A hydrogen bomb relies on the energy released from a fission reaction to heat and compress the hydrogen to trigger fusion, which can also generate additional fission reactions. In a large thermonuclear device, about half of the yield of the device comes from fission of depleted uranium. The fusion reaction doesn't really contribute to fallout, but because the reaction is triggered by fission and causes further fission, H-bombs generate at least as much fallout as atomic bombs. Hydrogen bombs can have much higher yields than atomic bombs, equivalent to megatons of TNT. The Tsar Bomba, the largest nuclear weapon ever detonated, was a hydrogen bomb with a 50 megaton yield.


Both types of nuclear weapons release vast quantities of energy from a small amount of matter and release most of their energy from fission, and produce radioactive fallout. The hydrogen bomb has a potentially higher yield and is a more complicated device to construct.

Other Nuclear Devices

In addition to atomic bombs and hydrogen bombs, there are other types of nuclear weapons:

neutron bomb: A neutron bomb, like a hydrogen bomb, is a thermonuclear weapon. The explosion from a neutron bomb is relatively small, but a large number of neutrons are released. While living organisms are killed by this type of device, less fallout is produced and physical structures are more likely to remain intact.

salted bomb: A salted bomb is a nuclear bomb surrounded by cobalt, gold, or other metal, such that detonation produces a large amount of long-lived radioactive fallout. This type of weapon could potentially serve as a "doomsday weapon", since the fall-out could eventually gain global distribution.

pure fusion bomb: Pure fusion bombs are nuclear weapons that produce a fusion reaction without the aid of a fission bomb trigger. This type of bomb would not release significant radioactive fallout.

electromagnetic pulse weapon (EMP): This is a bomb intended to produce a nuclear electromagnetic pulse, which can disrupt electronic equipment. A nuclear device detonated in the atmosphere emits an electromagnetic pulse spherically. The goal of such a weapon is to damage electronics over a wide area.

antimatter bomb: An antimatter bomb would release energy from the annihilation reaction that results when matter and antimatter interact. Such a device has not been produced because of the difficulty synthesizing significant quantities of antimatter.


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  • Hansen, Chuck (1995). Swords of Armageddon: U.S. Nuclear Weapons Development since 1945 (2nd ed.). Sunnyvale, California: Chuklea Publications. ISBN 978-0-9791915-0-3.
  • L'Annunziata, Michael (2016). Radioactivity: Introduction and History, From the Quantum to Quarks. Elsevier. ISBN 9780444634962.
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Helmenstine, Anne Marie, Ph.D. "Differences Between Hydrogen and Atomic Bombs." ThoughtCo, Apr. 5, 2023, thoughtco.com/hydrogen-bomb-vs-atomic-bomb-4126580. Helmenstine, Anne Marie, Ph.D. (2023, April 5). Differences Between Hydrogen and Atomic Bombs. Retrieved from https://www.thoughtco.com/hydrogen-bomb-vs-atomic-bomb-4126580 Helmenstine, Anne Marie, Ph.D. "Differences Between Hydrogen and Atomic Bombs." ThoughtCo. https://www.thoughtco.com/hydrogen-bomb-vs-atomic-bomb-4126580 (accessed June 1, 2023).