A nuclear weapon, nuclear bomb or a nuke, is a weapon that suddenly releases the energy in the nucleus of certain types of atoms. When triggered, the device releases a huge amount of energy in the form of a nuclear explosion.
Nuclear explosions can destroy a city and kill most of its people. They also make nuclear fallout. This radioactive material can make people ill. Nuclear weapons are the most damaging weapons mankind has created.
The first nuclear weapons were built by the United States during World War II. Two nuclear weapons were used to attack cities in Japan. They were the only times nuclear weapons were used in war.
There are two types of nuclear weapons: fission weapons (also called atomic bombs or A-Bombs) and fusion weapons (also called hydrogen bombs, H-Bombs, or thermonuclear weapons). They make energy for the nuclear explosion in different ways. Fusion weapons make bigger explosions. Fission weapons use a special isotope of uranium or plutonium. Fusion weapons use a special isotope of hydrogen. Nuclear weapons have been used twice in war, both by the United States in the atomic bombings of Hiroshima and Nagasaki in 1945.
Since the atomic bombings of Hiroshima and Nagasaki, nuclear weapons have been detonated over 2,000 times for testing and demonstration. Only a few nations possess such weapons or are suspected of seeking them. The only countries known to have detonated nuclear weapons and to say they have them are (in order from the first time the country had tested them) the United States, the Soviet Union (succeeded as a nuclear power by Russia), the United Kingdom, France, China, India, Pakistan, and North Korea. Israel is believed to have nuclear weapons, but in a policy of deliberate ambiguity, does not say so. Germany, Italy, Turkey, Belgium and the Netherlands share nuclear weapons with other countries. South Africa is the only country that has independently developed and later renounced and dismantled its nuclear weapons.
The Treaty on the Non-Proliferation of Nuclear Weapons aims to reduce the spread of nuclear weapons. Its effectiveness has been questioned.
History
In the years after 1895, physicists began to understand how atoms are made.
In 1939, physicists began to understand the theory of nuclear fission weapons, but no country knew how to build one. When World War II started, Germany, the United Kingdom, and the United States wanted to build nuclear weapons. The United Kingdom started working in 1939 but found it so expensive that it gave up in 1942. Later that year, the United States started a very large program to build nuclear weapons. Building upon the work done in the United Kingdom, the program was called the "Manhattan Project".
By August 1945, the Manhattan Project had built three nuclear fission weapons. Two of the bombs were used by the United States to attack the cities of Hiroshima and Nagasaki in Japan. People from the Manhattan Project believe that around 105,000 people were killed and 94,000 were hurt when the bombs were used. Medical professionals later came to believe that more than 225,000 people died when everyone who was affected after long periods of time has been counted. Japan announced its surrender after the atomic bombings of Hiroshima and Nagasaki.
After World War II, the Soviet Union also began working to create nuclear weapons.
How they work
One way that nuclear weapons release energy is by breaking atoms apart. Called nuclear fission, that the basis for atomic bombs. Specific isotopes of uranium or plutonium are typically used in the weapons. Those elements can be made to undergo nuclear fission and have a nuclear chain reaction.
Another process can be used to create nuclear weapons with even bigger explosions and then releasing much more energy by fusing atoms together. That process is called nuclear fusion, and weapons based on the process are called hydrogen bombs or thermonuclear weapons. Specialized isotopes of hydrogen are typically used in the weapons.
Nuclear weapons produce a very large amount of energy and radiation, which can kill people or animals within several kilometers. Most of the radiation is X-rays, which heats the air to produce a huge nuclear fireball. The rapid expansion of the fireball creates a dangerous shock wave that can destroy houses or buildings several kilometers away. The radiation can cause radiation poisoning and also has the potential to cause mutations in the DNA, which can cause cancer.