Radioactivity | Definition, types, Equation, Application

Radioactivity

The phenomenon of spontaneous disintegration of Unstable nucleus with emission of Alpha, Beta and Gamma ray's is known as Radioactivity.

What are the Radioactive Elements

The Element or Substance Containing Unstable atomic nuclei is Consider to be a Radioactive Substance.

In Periodic table, all the element having atomic number 83 or more are generally unstable in order to achieve stability. This heavy element are radioactive elements.

Example: Uranium (U), Radium (Ra), Thorium (Th) etc.

What is Radioactivity

Radioactivity is the phenomenon of spontaneous disintegration of the nucleus of an atom with the emission of one or more radiation like Alpha particle, Beta particle and Gamma Rays.

Unit :

S.I Unit of Radioactivity is Becquerel(Bq)
1Bequerel (Bq) = 1 Disintegration/second

Currie
The activity of Radioactivity sample is said to be one Curie.

1Curie(Ci)=3.7×10¹⁰decays/second

Rutherford
The activity of a radioactive sample is said to be a one Rutherford.

1Rutherford(Rd)=10⁶decays/second

Radioactive Decay

it is the transformation process in which radioactive rays are emitted from the nucleus of the atom cannot be accelerated and Slow Down by any physical or chemical process.

It is also known as Nuclear decay, nuclear disintegration, or radioactive disintegration.

Radioactive decay is a spontaneous or random process that occurs at Microscopic level (or individual atoms). Since, it is impossible to predict exactly when a single unstable nucleus will decay, the rate of decay of a group of atoms may be predicted based on decay constants or half-lives

Radioactive decay law

According to this law, the rate of decay of Radioactive Atom at any instant is proportional to the number of Atom present at that instant.

Radioactivity decay law equation

Where, Lambda is decay constant and N is number of undisintegrated nucleus present in the sample at any instant t.

Term’s Related to Radioactivity

Half-life Cycle

Half-life cycle Equation

The life of the half- life of a radioactive element is defined as the time taken for half number of atoms of the element to disintegrate (or decay) or to become stable.

Or we can also say that Half-life of radioactive element is defined as the time during which half the number of Atom present initially in the sample of the element decay

Mean Life/ Average Life

It is represented by (Tau)

Average life of radioactive element can be obtained by calculating the total life time of all the atoms of the radioactive element and dividing it by the total number of Atom present initially in the sample of the element.
Equation.

Mean life of Radioactive Elements

Time Required to Decay

it is denoted by 't'
Equation.

Time Required to Decay

Decay Constant

Its is represented by lambda
Radioactive decay constant may be defined as the reciprocal of the time during which the number of Atom in radioactive substance reduces to 36.8% of their initial number.
Equation

Decay constant equation

Radioactive displacement law

The law of radioactive displacement is also known as Fajan’s and Soddy law.
This law describes which chemical element and isotopes created during the particular type of Radioactive Decay.

Types of Radioactive Decay

1. Alpha rays

It is denoted by Alpha (α).
Also Known as Double positively charged Helium atom.
There are positively charged Helium nuclei.
In Alpha Decay the mass number of the product Nucleus is four less than that of decaying during the Particular type of Radioactive decay.

^AX_Z = ^A-4Y_Z-2 + ⁴He₂ + q

2. Beta rays:

It is denoted by Beta (β).
They are negatively charged particle which have a similar feature like electron.
They have only charge but no mass.
In Beta Decay, the mass number of product nucleus remains same but atomic number Increases or Decreases by One.
It can further Classified in to two Categories.

1. Beta-minus decay

In beta-minus decay, an Electron and an Antineutrino are created and emitted from the nucleus via the reaction given below:

n = p + e^- + q

^AX_Z = ^AY_Z+1 + ⁰e_-1 + q

³²P_{15 =} ³²S₁₆ + ⁰e_-1 + q

2. Beta-Plus Decay

In beta-plus decay, a positron and a neutrino are created and emitted from the nucleus via the reaction given below:

p = n + e^- + q

^AX_Z = ^AY_Z-1 + ⁰e₊₁ + q

²²Na_{11 =} ²²Na₁₀ + ⁰e₊₁ + q

3. Gama ray's:

It is denoted by Gama (γ).
They are charge less Proton which are highly energetic they travel in the form of electromagnetic wave and has a speed equal to the light or due to high frequency.
They are highly energetic and have highest penetrating power.
A gamma ray is emitted when alpha or beta decays results in a daughter nucleus in an excited state. Atom then return to ground state by a single photon transition or successive transitions involving more than one photon.

^AX_Z = ^AX_Z + γ

**The emission of alpha, and beta is from the Nucleus result in the form of a difference element (Atomic number goes on decreasing) but, the emission of Gama Ray's doesn't have any role in the formation of different elements.

Application Of Radioactivity

1. GH-Counter:

The Geiger Muller counter (or GH-Counter) is a device which can detect the presence of radioactive substance and can also measure is radioactivity.

2. Carbon Dating

Carbon-14 is made in the Upper atmosphere.
The half-life of C-14 is 5730.
As an age signature levels of C-14 in carbon-based artifacts are compared to modern levels.
It is a technique of estimating the age of remains of plants living organisms. such as plant or animal by measuring radioactivity by Carbon-14.

Carbon dating formula

where,
t = the age of the rock or minerals specimen
lambda is the appropriate decay constant
D is the number of atoms of a daughter product today
P is the number of atoms of the Parent isotope today.

Nuclear Energy (Or Atomic energy)

Mass defect Equation

The energy produced by nuclear fission or fusion is known as a nuclear.

Energy in a nuclear reaction there is a loss of mass. This mass is converted into energy and is given by mass defect Equation.

E=mc²

Where, 'E' is Energy and 'm' is mass loss.

It is a formula of atom bomb.

Transmutation of less stable nuclei into more tightly bound nuclei provides an excellent possibility of releasing nuclear energy.

Two distinct ways of obtaining energy from nucleus are given as below:

Nuclear Fission
Nuclear Fusion

Nuclear Fission

Nuclear Fission Reaction

It's the Breaking large atom into smaller atom.
It is the phenomenon of splitting of a heavy nucleus into two (or more) smaller nuclei with the release of nuclear energy.
For Nuclear Fission enriched Uranium (U²³⁵)and Plutonium (P²³⁹) are used.

Types of Nuclear Fission

There are types of nuclear fission

1. Control Nuclear Fission

2. Uncontrolled Nuclear Fission

1. Control Nuclear Fission

This type of fission takes place in a nuclear reactor. Where Fission reaction is reduced and the energy produce can be used for producing electricity. In a nuclear reactor in which Uranium U²³⁵ isotope is used as a nuclear fuel.

Future of Nuclear Reactor

Fission reaction takes place at a control rate.
A moderator is used to slow down the speed of fast moving neutron Graphite or Heavy Water (D₂O) is used as a moderator.
A Control device is known as a control road are used to control the flow of neutron by observing them ( Boron and Cadmium roads are used as Control road).
Control roads become a saturated with a neutron after definite period of time and hence need to be replaced after a certain period of time.
Ordinary Water or Heavy water are used as a coolant.

2. Uncontrolled Nuclear Fission

Atomic Bomb
(Uncontrolled Fusion Reaction)

These are the fission reaction which takes place in atom a large amount of heat energy is produced and the Process continuous until entire amount of fissionable material get exhausted. In Atom Bomb both enriched Uranium U²³⁵ and P²³⁹ are used.

Enriched Uranium U²³⁵

Natural Uranium occur as U²³⁸ and 0.7% of U²³⁵.
In which U²³⁸ is not fissionable. Therefore, U²³⁵ has to separated and concentrated for Nuclear Fission in uranium with large quantity or love u 235 and Concentrated for Nuclear Fission.
Uranium with large Quantity U²³⁵ Isotopes is Called as enriched Uranium.

Nuclear Fusion

Nuclear Fusion reaction

Combining of smallest substance to form a bigger one is called Nuclear Fission.

It’s the process of fusing of two (or more) lighter Nuclear to form a single heavy nucleus. In this reaction also large amount of heat energy is produced.

**Nuclear Fission takes place in a sun and star and it is one of the main source of their light and heat energy.

In hydrogen bomb Nuclear Fission reaction takes place (for starting a fusion reaction a small amount of propane energy required. Which can also be obtained by fission reaction fission reaction) act as a trigger for starting a fission reaction.

List of Nuclear Power Plant In India

Nuclear Power plant

1. NPCIL - Tarapur (Maharashtra)

Type: Boiling water reactor (BWR)

& Pressurized heavy water reactor (PHWR)

Total capacity: 1,400 MW

2. NPCIL - Rawatbhata (Rajasthan)