Electrons are considered to be the smallest unit of an atom. It is the lightest, steady subatomic particle. It is considered massless & it possesses a negative charge of 1.602 × 10-19 coulomb. Its leftover mass is only 9.1093837x 10-31 kg.

Its existence can be found outside the surroundings of an Atom’s Nucleus.

They are considered to be the primary means for conducting current.

For example

 In electrical conductors, whatever the current flows results from a Movement of one atom to another atom from negative terminals to positive terminals and in Semiconductors, an atom which is a deficit in it is considered as ‘Hole’, and holes move from positive terminal to negative terminal.

Definition of An Electron

• They are considered the smallest and most massless negatively charged subatomic particles of an atom which move freely outside an atom’s Nucleus.

Discovery of electrons

• Renowned English physicist J.J. Thomson firstly discovered it in 1897.
• It was done as during 1880 scientists searched cathode rays to look for the electrical properties in matter.
• The study of cathode rays was started in 1854 and 1858, when the vacuum tube was sealed, and Cathode rays were discovered. 
• The air was evacuated when the tube was sealed, forcing an electric current between two electrodes. 
• A green glow on the glass tube wall was discovered, and a shadow was also seen by Johann W. Hittorf.
• The shadow proves that the cathode originated from the cathode rays.
• Further, in 1879 by William Crookes, it was discovered that magnetic fields bend cathode rays, and their direction gave an idea of their charge to be negative in nature.
• Crookes believed that particles were electrically charged, and this does not have a clarified assumption of whether they were electric particles or radiation on the cathode, As they were affected by magnetic fields.

J.J.Thomson’s Experiment 

• J.J. Thomson performed Hertz’s experiment with a better vacuum as he was in view that residual gas during Hertz’s experiment might have reduced the electric field’s effect on the cathode rays.
• He covered both the ends of the tube with aluminium plates denoting positive and negative terminals.
• Luminescence on the tube’s glass was observed, and rays moved down when the negative terminal was placed up, and rays moved up when the positive terminal was placed up.
• The difference was directly proportional to the difference between the plates.
• From the deflections electrical and magnetic, Thomson could calculate the ratio between mass and charge.
• That’s how they were first identified as subatomic particles.

Identification of positive ions

• Being negatively charged, some positively charged particles were also discovered in tubes during Crooks’ experiment.
• Their mass to charge ratio was approximately 1000 times more than electrons.
• In 1913 Thomson further analysed Wein’s apparatus to identify and separate different ions.
• He also measured the mass to charge ratio of different ions.

Cathode rays and cathode tube 

• J.J.Thomson created a glass tube on which partial or limited air can be placed.
• A large electrical voltage is applied to two ends.
• The ray was discovered travelling from the electrode, and that ray was called a cathode ray.
• The tube in which this experiment was performed was known as the cathode ray tube.

Charge 

• It carries a negative charge of 1.602 × 10-19 coulomb.

Mass 

• It possesses a mass of  9.10938356 × 10-31 kilograms.

Features 

• The atom is considered to be a building block unit of matter.
• The nucleus is considered the core of the atom.
• Electrons, protons and neutrons generally revolve around the nucleus.
• Protons are neutral in terms of electric charge.
• While neutrons carry positively charged ions in them.
• They have a negative charge.
• It generally weighs less than 1836 times that of the weight of protons and neutrons.

Applications 

1. They are used for particle research and materials differentiation.
2. They are used In school labs, laboratories etc., for detailed analysis of any matter.
3. They are used for making electronic microscopes.
4. They are used in industries for researching various products.

Meaning of Hydrogen

• Hydrogen, first known in 1788 as the very beginning element of the periodic table, Is a gas whose nature is Non-Metallic and is placed first as an atomic number.
• For example, this element is also used in water as H2O.
• Hydrogen is one of the abundant elements in the universe, with only 0.24% presence in Earth’s crust.
• Nonetheless, it is widely present in the form of water in oceans, rivers and lakes.

Nature of Hydrogen 

• Hydrogen being 
• Colourless:- it does not have any colour.
• Odourless:- it does not have a smell of its own.
• Tasteless:- it does not have any taste associated with itself.
• Flammable:- it is a fire catching gas.
• Symbol:- H
• Atoms weight:-1.00797.

Examples of Hydrogen 

• The hydrogen atom is a building block of water and is widely present in oceans, rivers and lakes.
• Used in industries for:
  • Purification of glass 
  • Heat treatments and welding 
  • Production of fertilisers 
  • Refining of petroleum etc.
• They are used to produce ammonia (NH3) used in fertilisers.
• It is also used to convert saturated fats and oil into unsaturated ones.
• Liquid hydrogen is used as fuel in spaceships etc.

Conclusion

• They are considered to be the tiniest unit of an atom.
• They are considered to be the primary means for conducting current.
• It is considered as massless; it possesses a negative charge of 1.6021766×10 -19 coulomb, and after that, its leftover mass is only 9.1093837x 10-31 kg.
• Their existence can be found outside the surroundings of an Atom’s Nucleus.
• They are considered to be the primary means for conducting current.