Atomic Models and discovery of subatomic particles.

Dalton's atomic model. Discovery of electron, proton, and neutron. Anode rays and cathode rays. Thompson's atomic model

Learner's Guide


In this session, we will learn about structure of an atom:

    • Is atom divisible?
    • What are subatomic particles and how are they discovered?
    • What is an atomic model?



According to ancient philosophers, every matter is made from ________________

  1. Atoms
  2. Molecules
  3. Compounds
  4. Elements
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What is matter made of according to ancient philosophers?



Dalton's atomic theory:





Success & Failure of Dalton's Theory:




Hint of presence of charge in matter?



In above video, why do you think, comb is attracting paper pieces?

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After combing, comb has become positively charged which is attracting negative electrons in paper pieces.

This experiment suggests that atoms are made from charge particles.



Discovery of electron and Thomson's Atomic Model:


Why did Thomson's model fail?


What happens when positive and negative charge come close to each other?

  1. They repel each other
  2. They attract each other
  3. Nothing happens
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2. They attract each other






Discovery of proton and Anode rays:



Discovery of Neutron:



Tip: Think before answering.

  • True or False?

    Atom is the smallest unit of matter.

    Difficulty Level: Easy


    Atoms are made from sub atomic particles-electron, proton, and neutron.

  •  Electron  Positive charge
     Neutron  Negative charge
     Proton  Neutral
    Difficulty Level: Moderate
     Electron  Negative charge
     Neutron   Neutral
     Proton   Positive charge
  • How do the gases from discharge tube removed?

    1. By blowing
    2. By vacuum pump
    3. By motor
    4. By fan
    Difficulty Level: Easy

    By vacuum pump

  • Anode and cathode rays are made from?

    1. Mass less particles
    2. Charged mass less particles
    3. Charged particles with some mass
    4. Neutral particles
    Difficulty Level: Moderate

    Charged particles with some mass