Electrons – Definition, Properties, Thomson’s Cathode Ray Experiment

An Introduction to Electrons

Electrons – Definition:

An electron is a negatively charged subatomic particle that is found in the atomic nucleus and in the electron cloud. Electrons are the most common subatomic particle in the universe.

S.NO	CONTENT
1	THOMPSON CATHODE RAY EXPERIMENT
2	DEFINE ELECTRONS
3	PROPERTIES OF ELECTRONS
4	ELECTRONS AND COMPOUND IONS
5	COMPLETE CATHODE EXPERIMENT

 

Thompson Cathode Ray Experiment

The Thompson Cathode Ray Experiment was an experiment conducted by J. J. Thomson in 1897. Thomson used a cathode ray tube to determine the nature of the cathode ray. He found that the cathode ray was composed of negatively charged particles, which he called electrons.

Define Electrons

Electrons are negatively-charged subatomic particles that orbit the nucleus of an atom. They are responsible for the chemical properties of atoms and molecules.

Properties of Electron

• An electron is a subatomic particle with a negative electric charge. It is one of the fundamental particles that make up atoms.
• The electron has a mass that is about 1/1837 the mass of a proton. It is a tiny particle, with a diameter of about 2.8 × 10-15 meters.
• The electron is a stable particle that does not change over time. It is one of the most common particles in the universe.

Electrons and Compound Ions

• The number of electrons in an atom is equal to the number of protons in the nucleus. The number of protons in a nucleus is also called the atomic number. The number of electrons in an atom can also be called the electron configuration.
• The electron configuration of an atom can be changed by adding or removing electrons. When an atom gains or loses electrons, it becomes an ion.
• An atom becomes a positive ion (cation) when it loses electrons.
• An atom becomes a negative ion (anion) when it gains electrons.
• When an atom becomes an ion, the number of protons in the nucleus remains the same, but the number of electrons changes.
• Compound ions are formed when two or more atoms join together to share electrons.
• The electron configuration of a compound ion can be different from the electron configurations of the individual atoms that make up the ion.

Thomson’s Cathode Ray Experiment

• Thomson’s cathode ray experiment was designed to determine the nature of cathode rays. Cathode rays were discovered by Johann Wilhelm Ritter in 1802. Ritter observed that when he placed a metal plate between a negatively charged cathode and an anode in a glass tube, the intensity of the light emitted by the tube decreased. Ritter concluded that the cathode rays were negatively charged and were being repelled by the metal plate.
• Thomson’s experiment consisted of a glass tube with a cathode and an anode, and a metal plate between the cathode and anode. Thomson used a magnet to deflect the cathode rays. When the magnet was placed near the cathode, the cathode rays were deflected towards the anode. When the magnet was placed near the anode, the cathode rays were deflected away from the anode. Thomson concluded that the cathode rays were negatively charged and were being repelled by the metal plate. Thomson also concluded that the cathode rays were made up of negatively charged particles that he called electrons.

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