All chemical elements consists of individual atoms or molecules , for example , Helium gas consists of millions of individual atoms of helium but oxygen gas consists of millions of molecules and each molecule contains two atoms of oxygen.
Atom consists of a nucleus which containing positive protons and neutral neutrons. Revolves around the nucleus a set of orbits, each orbit contains a set of negative electrons.
The number of protons ( Z ) and neutrons ( N ) called Atomic mass number ( A ) and number of protons called atomic number ( Z ).
The element has many isotopes; there are a stable isotopes and unstable isotopes.
Most stable nuclides have even numbers of neutrons and protons. Nuclides with odd numbers of neutrons and protons are usually unstable.
All isotopes for a given element have the same number of protons and differ
only in the number of neutrons.
For example, all isotopes of uranium have 92 protons.
Unstable isotopes seek greater stability by decay or disintegration of the nucleus to a more stable form.
Nuclear decay may include a release of energy from the nucleus or may cause a change in the number of protons or neutrons within the nucleus.
If the nuclear decay causes a change in the number of protons, there is a change of element.
Radio nuclides are unstable isotopes seek greater stability by emitting radiation.
There are several ways of decay to reach stability such as;
1. Alpha- particle emission
Alpha-particle consisting of two protons and two neutrons, when alpha-particle released from the nucleus, resulting in a decrease of atomic mass number ( A ) by four and neutron ( N ) decrease by two, also protons ( Z ) decrease by two.
The mass of the released alpha particle is so great that they travel only a few centimeters in air and are unable to penetrate a thin paper.
2. Beta-particle emission:
Beta- particle emission is found in nuclides with a neutron excess. Beta Particle is a negative electron which emitted from the nucleus accompanied by an antineutrino. Due to Beta particle emission from the nucleus a neutral neutron will undergo a positive proton which remains in the nucleus.
So Beta particle emission decreases the number of neutrons ( N ) by one and increase the number of protons ( Z ) by one and atomic mass number ( A ) remains unchanged.
For example, all isotopes of uranium have 92 protons.
Unstable isotopes seek greater stability by decay or disintegration of the nucleus to a more stable form.
Nuclear decay may include a release of energy from the nucleus or may cause a change in the number of protons or neutrons within the nucleus.
If the nuclear decay causes a change in the number of protons, there is a change of element.
Radio nuclides are unstable isotopes seek greater stability by emitting radiation.
There are several ways of decay to reach stability such as;
1. Alpha- particle emission
Alpha-particle consisting of two protons and two neutrons, when alpha-particle released from the nucleus, resulting in a decrease of atomic mass number ( A ) by four and neutron ( N ) decrease by two, also protons ( Z ) decrease by two.
The mass of the released alpha particle is so great that they travel only a few centimeters in air and are unable to penetrate a thin paper.
2. Beta-particle emission:
Beta- particle emission is found in nuclides with a neutron excess. Beta Particle is a negative electron which emitted from the nucleus accompanied by an antineutrino. Due to Beta particle emission from the nucleus a neutral neutron will undergo a positive proton which remains in the nucleus.
So Beta particle emission decreases the number of neutrons ( N ) by one and increase the number of protons ( Z ) by one and atomic mass number ( A ) remains unchanged.
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