Isotopes


 
 
Concept Explanation
 

Isotopes

Isotopes: These are defined as the atoms of the same element, having the same atomic number but different mass numbers. E.g. there are 3 isotopes of hydrogen atom, namely protium (1H), deuterium (2H) and tritium (3H).

In other words, it can be said that isotopes have same number of protons but differ in the number of neutrons. Each isotope of an element is a pure substance. Since, chemical properties of elements largely depend on their electronic configuration or outermost electrons and as the isotopes of an element have similar electronic configuration.Therefore, isotopes of an element have the same chemical properties. We know that, masses of isotopes of elements are different. Since, physical properties such as density, light scattering etc., depend on mass therefore, these are different for isotopes of an element.

Average Atomic Mass: If an element has no isotopes, the mass of its atom would be the same as the sum of protons and neutrons in it. But if an element occurs in isotopic forms, then from the percentage of each isotopic form, the average mass is calculated as:

Average atomic mass of an element:[(Atomic mass of isotope I x percentage of isotope I) + (Atomic mass of isotope II x percentage of isotope II) +...]

Example: The two isotopic forms of chlorine atom with masses 35u and 37u occur in the ratio of 3:1. Therefore, the average atomic mass of chlorine atom, can be calculated as:

The average atomic mass of chlorine atom:

The 3:1 ratio of isotopes mean 75% of ^3^5Cl_1_7 and 25% of ^3^7Cl_1_7 

Therefore, average atomic mass of chlorine is frac{35times 75+37times 25}{100}=35.5

We can calculate the number of neutrons of different isotopes.

Number of Neutrons = Atomic mass - Atomic number

For eg: There are three isotopes of carbon(C) with same numbers of protons and electrons but differ in number of neutrons.

                               _6^{12}C:::::::::_6^{13}C::::::::::_6^{14}C

No. of neutrons  12-6 = 6        13-6 =7        14-6 = 8

Here, 35.5 u is not the atomic mass of any one atom of chlorine but it shows that its given amount contains both the isotopes and their average atomic mass is 35.5 u.

NOTE: The fractional atomic masses of elements are due to the fact that all elements have isotopes. The isotopes of an element have different atomic masses. Since the atomic mass of an element is the average atomic mass of all the natural isotopes of that element, most elements have fractional atomic masses.

Applications of Isotopes:

  • An isotope of uranium (U-235) is used as a fuel for the production of electricity in nuclear reactors.
  • U-238 is used to determine the age of very old rocks and even the age of the earth.
  • An isotope of cobalt (Co-60) is used to remove brain tumours and in the treatment of cancer.
  • An isotope of carbon (C-14) is used to determine the age of old specimen of wood or old bones of living organisms.
  • An isotope of iodine (I-131) is used in the treatment of goiter (thyroid complications).
  • Sample Questions
    (More Questions for each concept available in Login)
    Question : 1

    Which of the following isotope of uranium is used as a fuel for the production of electricity in nuclear reactors?

    Right Option : B
    View Explanation
    Explanation
    Question : 2

    Tritium is the isotope of H whith number of neutrons, electrons and protons respectively:

    Right Option : B
    View Explanation
    Explanation
    Question : 3

    How many isotopes are there in hydrogen atom ?

    Right Option : C
    View Explanation
    Explanation
    Chapters
    Pre-Historic Period
    Indus Valley Civilization
    Vedic Civilization
    Religious Reform Movement
    The Early Kingdoms
    The Mauryan Empire
    Post Mauryan Period
    The Age Of The Guptas
    Post Gupta Era
    Age of Rajput
    Khilji Dynasty
    Slave Dynasty
    Tughlaq and Sayyid Dynasty
    Vijaynagar Empire And Bahamani Kingdom
    Mughal Empire And Beyond
    Lodhi Dynasty
    Cholas, Chalukyas and Pallavas
    Arab Invasions
    Bhakti and Sufi Movement
    Rise of Sikhs, Jats and Marathas
    Administrative Structure of Delhi Sultanate
    Architecture During Medivial India
    Advent Of The Europeans
    Post Mughal Period
    Rise of New States in 18th Century
    Growth of British Paramountacy
    Socio Religious Reforms
    Constitutional Development of India
    Indian Struggle Against British Rule
    The Revolt Of 1857
    Education Under British Rule
    Role of Press in Freedom Struggle
    First Phase of National Movement
    Second Phase of National Movement
    Third Phase of National Movement
    Constitutional Development in India
    Constituent Assembly
    Union And Its Territory
    Structure of Indian Constitution
    Fundamental Rights and Duties
    The Union Executive
    The Union Legislature
    Constitutional Amendments and Provisions
    Judiciary In India
    Emergency Provisions
    Center - State Relations
    The State Executive
    The State Legislature
    Election Commission Of India
    Constitutional Organisation
    Non-Constitutional Organisation
    Local Self Goverment
    India - Size And Location
    Geological History Of India
    The Physical Features Of India
    Climate Of India
    Soils In India
    Natural Vegetation
    Windlife Conservation In India
    Drainage System of India
    Irrigation System Of India
    Agriculture In India
    Livestock And Fisheries In India
    Minerals And Energy Resources In India
    Means Of Transport In India
    Major Industries In India
    Tribes of India
    Census of India 2011
    Music
    Dance
    Theatre
    Pantings
    Art, Architecture & Culture of India
    Bio-Diversity
    Earth And Its Structure
    Land Rock And Soil
    Atmosphere, Climate And Weather
    Oceanography
    Human And Regional Geography
    Economic Growth And Development
    Sectors Of Indian Economy
    Economic Planning Of India
    Fiscal And Monetary Policy In India
    Infrastructure In India
    Effects Of British Rule On Indian Economy
    National Income
    Banking System In India
    Poverty And Unemployment
    Inflation And Trade Cycles
    Major Institutions
    Environmental Studies
    Tissues In Organism
    Cytology
    Classifucation Of Plants
    Structural Composition Of Plants
    Nutrition In Plants, Harmones And Plant Disease
    Ecosystem
    Classification In Animals
    Nutrition In Animals
    Human Digestive System
    Human Respiratory System
    Human Skeleton System
    Human Excretory System
    Human Nervous System
    Human Circulatory System
    Human Endocrine System
    Human Reproductive System
    Genetics
    Human Diseases
    States Of Matter
    Metals And Non Metals
    Acid Bases And Salts
    Element Compounds And Mixture
    Physical And Chemical Change
    Carbon And Its Compounds
    Periodic Classification
    Fuel, Combustion And Flame
    Environmental Chemistry
    Rest And Motion
    Work Power And Energy
    Gravitation
    Pressure And Its Effects
    Simple Harmonic Motion
    Sound and Waves
    Heat And Temperature
    Light - Reflection
    Electricity And Magnetism
    Modern Physics
    Science And Technology
    Force And The Laws Of Motion
    Light - Refraction
    Dispersion And Human Eye
    Magnetic Effect Of Electric Current
    Atom And Molecule
    Chemistry In Everyday Life
    Units And Dimensions
    Content / Category
    Class / Course
     
     


    Students / Parents Reviews [20]