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Charged Particles in Matter

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Can we deduce from these actions that rubbing two items together causes them to become electrically charged? The presence of charged particles in an atom was discovered thanks to the efforts of many scientists. By 1900, it was established that the atom was an indivisible particle that contained at least one sub-atomic particle, the electron, which J.J. Thomson discovered. E. Goldstein discovered novel radiations in a gas discharge in 1886, long before the electron was detected, and named them canal rays. 

These rays were positively charged radiations, and their discovery led to the discovery of yet another subatomic particle. This subatomic particle had a charge equivalent to the electron’s in magnitude but opposite in sign. It had a mass of around 2000 times that of an electron. Proton was the name given to it. In general, an electron is denoted by the letter e–, while a proton is denoted by the letter p+. A proton’s mass is one unit, and its charge is one plus one. An electron’s mass is deemed negligible, and its charge is a negative one.

Let us try the following activities to better understand the nature of charged particles in the matter:

  1. If you run a plastic comb through your hair and then position it near small pieces of paper, we can see static electricity. The comb is drawn to the paper. The charged comb causes an opposite charge in the paper, and because opposite charges attract, the paper adheres to the comb.
  2. Placing a balloon against a wall or ceiling after rubbing it against a woollen or synthetic jumper. The balloon is held in place by the attraction of opposite charges.

Charged Particles in Matter

An atom appeared to be made up of protons and electrons that balanced each other’s charges. It also looked that the protons were inside the atom because whereas electrons could be easily removed, protons could not.

A charged particle is a particle having an electric charge in physics. It might be an ion, such as a molecule or atom, having an excess or deficiency of electrons in comparison to protons. It may also be an electron, a proton, or another primary particle, all of which are thought to have the same charge (except antimatter). An atomic nucleus devoid of electrons, such as an alpha particle, might also be a charged particle.

Discovery of Subatomic Particle

Discovery of Existence and Charge of an electron

In the year 1897, a British physicist named J.J Thompson hypothesized that an atom contains at least one negatively charged particle. While working on an experiment, he discovered electrons. Gas was pushed through a glass discharged tube at low pressure during the experiment.

Two electrodes were installed at the glass discharge tube’s two opposite ends, which were then connected to a high voltage source (battery). The electrode that was connected to the negative end was known as the cathode, and the electrode that was connected to the positive end was known as the anode.

The cathode emitted a stream of negatively charged particles, which Thomson observed. The stream of particles was also moving towards the anode. Cathode rays are streams of negatively charged particles ejected from the discharge tube’s cathode end. He dubbed it “corpuscles,” which was later shortened to “electron.”

Discovery of Proton

Rutherford discovered proton while doing the famous gold foil experiment. In 1886, Goldstein discovered the presence of positively charged rays in a discharged tube while conducting an experiment with a perforated cathode. The experiment was comparable to J.J. Thomson’s, but the circumstances were different. As a result, charged particles were emitted from the anode.

Canal rays are the positively charged radiations emitted from the discharge tube’s anode end. Anode rays and canal rays were given to the rays. Protons were discovered after a series of experiments. The particles that contribute to the atom’s positive charge are known as protons.

The particles’ mass was discovered to be 2000 times greater than that of an electron. The letter “p” was used to symbolize protons. The positive charge of 1.6 × 10-19 coulomb is the absolute charge of a proton. A proton has a mass of 1.6 × 10-24 g and is regarded as one of the smallest particles in the universe (which is the mass of a hydrogen atom). A proton’s mass is regarded as one unit, while its charge is regarded as +1.

Discovery of Neutron

It wasn’t until 1932 that the neutron was found. James Chadwick discovered it by calculating the mass of the neutral particle using scattered particles. The atom’s nucleus contains the subatomic particle “neutron.” A neutron is a neutral particle that is represented by the letter “n.” The mass of a neutron is 1.6 × 10-24 grams.

Gram is an insufficient unit for calculating such minute subatomic particles. As a result, they are calculated in either Dalton or amu (atomic mass unit). A proton and a neutron have a mass of about 1 amu in common.

Name Symbol Charge Relative Charge Mass (kg) Relative Mass

Electron

e-

-1.6 × 10-19 C

-1

9.1 * 10-31 kg

negligible

Proton

p+

1.6 × 10-19 C

+1

1.672 * 10-27 kg

1 u

Neutron

n

0

0

1.674 * 10-27 kg

1 u

Many questions arose as a result of the discovery of subatomic particles. One of them was the arrangement of these subatomic particles in an atom. As a result, various models of these charged particles have been proposed. These are the fundamentals of the enormous field of atom structure.

Sample Questions

Question 1: Write two activities to understand the nature of charged particles in matter.

Answer:

If you run a plastic comb through your hair and then position it near small pieces of paper, we can see static electricity. The comb is drawn to the paper. The charged comb causes an opposite charge in the paper, and because opposite charges attract, the paper adheres to the comb.

Placing a balloon against a wall or ceiling after rubbing it against a woollen or synthetic jumper. The balloon is held in place by the attraction of opposite charges.

Question 2: How was electron discovered?

Answer: 

In the year 1897, a British physicist named J.J Thompson hypothesized that an atom contains at least one negatively charged particle. While working on an experiment, he discovered electrons. Gas was pushed through a glass discharged tube at low pressure during the experiment.

Two electrodes were installed at the glass discharge tube’s two opposite ends, which were then connected to a high voltage source (battery). The electrode that was connected to the negative end was known as the cathode, and the electrode that was connected to the positive end was known as the anode.

The cathode emitted a stream of negatively charged particles, which Thomson observed. The stream of particles was also moving towards the anode. Cathode rays are streams of negatively charged particles ejected from the discharge tube’s cathode end. He dubbed it “corpuscles,” which was later shortened to “electron.”

Question 3: How was proton discovered?

Answer: 

Rutherford discovered proton while doing the famous gold foil experiment. In 1886, Goldstein discovered the presence of positively charged rays in a discharged tube while conducting an experiment with a perforated cathode. The experiment was comparable to J.J. Thomson’s, but the circumstances were different. As a result, charged particles were emitted from the anode.

Canal rays are the positively charged radiations emitted from the discharge tube’s anode end. Anode rays and canal rays were given to the rays. Protons were discovered after a series of experiments. The particles that contribute to the atom’s positive charge are known as protons.

The particles’ mass was discovered to be 2000 times greater than that of an electron. The letter “p” was used to symbolize protons. The positive charge of 1.6*10-19 coulomb is the absolute charge of a proton. A proton has a mass of 1.6*10-24 g and is regarded one of the smallest particles in the universe (which is mass of a hydrogen atom). A proton’s mass is regarded as one unit, while its charge is regarded as +1.

Question 4: How was neutron discovered?

Answer: 

It wasn’t until 1932 that the neutron was found. James Chadwick discovered it by calculating the mass of the neutral particle using scattered particles. The atom’s nucleus contains the subatomic particle “neutron.” Neutron is a neutral particle that is represented by the letter “n.” The mass of a neutron is 1.6 x 10-24 grams.

Gram is an insufficient unit for calculating such minute subatomic particles. As a result, they are calculated in either Dalton or amu (atomic mass unit). A proton and a neutron have a mass of about 1 amu in common.

Question 5: Give a short timeline of the discovery of subatomic particles.

Answer: 

The presence of charged particles in an atom was discovered thanks to the efforts of many scientists. By 1900, it was established that the atom was an indivisible particle that contained at least one sub-atomic particle, the electron, which J.J. Thomson discovered. E. Goldstein discovered novel radiations in a gas discharge in 1886, long before the electron was detected, and named them canal rays. 



Last Updated : 10 Mar, 2022
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