To understand radioactivity, you must understand the nucleus. A nucleus of an atom is the positively charged central core of an atom, consisting of protons and neutrons and containing nearly all its mass.
A material containing unstable nuclei is considered to be nuclear radioactive. This is because the strong force does not tightly hold the nucleus together. The Strong Nuclear Force (also referred to as the strong force) is one of the four basic forces in nature (the others being gravity, the electromagnetic force, and the weak nuclear force). As its name implies, it is the strongest of the four. However, it also has the shortest range, meaning that particles must be extremely close before its effects are felt. Its main job is to hold together the subatomic particles of the nucleus (protons, which carry a positive charge, and neutrons, which carry no charge. These particles are collectively called nucleons). The strong force is the most powerfully felt by an atom when the nucleus is small. Smaller nuclei are more tightly held by this force than large nuclei with huger number of protons and bigger numbers of neutrons. When the strong force is not stronger enough to overcome the repulsion of the protons, we can observe nuclear decay. Nuclear decay, radioactivity, radioactive disintegration or nuclear disintegration) is the process by which an unstable atomic nucleus breaks down and loses energy by radiation. |
Henri Becquerel was a French engineer, physicist, Nobel laureate, and the first person to discover evidence of radioactivity. For work in this field he, along with Marie Skłodowska-Curie and Pierre Curie, received the 1903 Nobel Prize in Physics.
Marie Cure furthered the work, and was highly esteemed for her devotion to science. Together with her husband, she was awarded half of the Nobel Prize for Physics in 1903, for their study into the spontaneous radiation discovered by Becquerel, who was awarded the other half of the Prize. In 1911 she received a second Nobel Prize, this time in Chemistry, in recognition of her work in radioactivity. |
The Curie's work with radiation led to important discoveries and understandings of nuclear radioactivity. This phenomenon of nuclear decay, when particles and energy are released from a nucleus, can occur in several ways. The three main types we will focus on:
Alpha decay Beta decay Gamma radiation Alpha decay is one process that unstable atoms can use to become more stable. During alpha decay, an atom's nucleus sheds two protons and two neutrons in a packet that scientists call an alpha particle. Since an atom loses two protons during alpha decay, it changes from one element to another. |
Gamma decay, type of radioactivity in which some unstable atomic nuclei dissipate excess energy by a spontaneous electromagnetic process. In the most common form of gamma decay, known as gamma emission, gamma rays (photons, or packets of electromagnetic energy, of extremely short wavelength) are radiated.
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In nuclear physics and nuclear chemistry, nuclear fission is a nuclear reaction or a radioactive decay process in which the nucleus of an atom splits into two or more smaller, lighter nuclei. This process can be used as a fuel in nuclear reactors and power plants.
In chemistry and physics, a self-sustaining series of reactions. In a chain reaction in a uranium-based nuclear reactor, for example, a single neutron causes the nucleus of a uranium atom to undergo fission. In the process, two or three more neutrons are released.
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