Charged Particles in Matter: Matter is defined as any substance that has mass and occupies space. All matter is made up of the smallest unit known as the “Atom”. Earlier, scientists believed that the atom is the smallest particle that can exist, but with time, they discovered that there is something inside the atom. In \(1886\), scientists noticed some radiations coming out of the atom, and this was the first step towards believing the fact that there was something inside the atom. By the \(1900{\rm{s}}\), scientists were quite sure about a charged particle known as an electron present inside the atom.

With rapid discoveries over the years, finally, the structure of the atom was proposed, and it was confirmed that each atom is composed of charged particles or subatomic particles inside it. These charged particles or subatomic particles in the matter are negatively charged electrons, positively charged protons, and neutrons without any charge.

According to the latest structure of the atom, an atom consists of a positively charged nucleus at the centre that is composed of protons and neutrons and electrons revolving around the nucleus in different orbits. The structure of an atom closely resembles our Solar System, where the Sun at the centre resembles the nucleus, and the planets moving around different orbits resemble electrons. Let’s have a brief discussion on the different ‘Charged Particles in Matter’ and their discoveries.

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Types of Charged Particles in Matter

The matter is made up of three types of charged, subatomic particles. They are:

1. Electrons – Negatively charged subatomic particles in an atom are known as electrons. An electron carries a charge of \(1.602 \times {10^{ – 19}}\) Coulomb in magnitude. The mass of an electron is \(\frac{1}{{1837}}\) times that of a proton.
2. Protons – Positively charged subatomic particles in an atom are known as protons. The charge of a proton is equal to the charge of an electron in magnitude; but the charge is positive. The mass of a proton is \(1.673 \times {10^{ – 27}}{\rm{Kg}}\). \({{\rm{H}}^{\rm{ + }}}\) ion or nucleus of a Hydrogen atom is an example of a proton.
3. Neutrons – Neutrons are neutral subatomic particles that are present in all atomic nuclei except ordinary hydrogen atoms. It has no electric charge at all, and its mass is equal to \({\rm{1}}{\rm{.67493}} \times {\rm{1}}{{\rm{0}}^{ – 27}}{\rm{Kg}}\). It means it is slightly heavier than the proton mass but almost 1839 times heavier than an electron.

Discovery of Charged Particles in Matter

According to Dalton’s Atomic Theory, John Dalton assumed atoms as the smallest and indivisible particles of matter. This concept was later proved wrong with the discovery of subatomic particles. Let’s learn about the discoveries of these subatomic particles in detail:

1. Discovery of Electron

In \(1897\), Joseph John Thomson discovered electrons through an experiment based on a cathode ray tube. In this experiment, A high voltage was applied across two electrodes at one end of the sealed glass tube, which generated a beam of particles to flow from the negatively charged electrode (cathode) to the positively charged electrode (anode). These rays were known as “cathode rays” as they originated at the cathode. To test the charge of the particle, Thomson placed two oppositely charged electric plates around the cathode ray. He noticed that the cathode rays were deflected away from the negatively charged electric plate and towards the positively charged plate. This concluded that the cathode rays were composed of negatively charged particles. Later these cathode ray particles were named “electrons”. J.J. Thomson proposed the Plum Pudding Model of an atom where he assumed that the electrons were embedded in the sea of positively charged matter.

2. Discovery of Proton

Eugen Goldstein was the first to observe positively charged particles in an atom through a series of experiments in which high voltage electricity was passed through a cathode tube containing gas at low pressure. A new type of ray was produced from the positive electrode (anode), which travelled towards the cathode. These new rays were termed by him as canal rays, positive rays, or anode rays.  

Later in \(1909\), Rutherford, through his famous gold foil experiment, discovered the proton. Alpha particles were bombarded on an ultrathin gold foil. He found that most of the particles penetrated through, and some scattered in various directions, and a few alpha particles were even completely deflected back towards the source. This proved that there are positively charged particles at the centre of the atom. Rutherford named it the proton, from the Greek word “protos,” meaning “first.” 

3. Discovery of Neutron

Neutrons are subatomic particles that do not have any charge at all, i.e., they are neutral. Along with the discovery of protons, by \(1920\), scientists knew that most of the mass of the atom was concentrated in a nucleus at the centre of an atom and that this central core of an atom contains protons. James Chadwick, in \(1932\) announced that the core also contained a new uncharged particle, which he termed as neutron. Thus, with the discovery of the neutron, a complete picture of an atom was clear. The Atomic model consists of three charged subatomic particles, electron, proton, and neutron.

Interaction of Charged Particles

When charged particles interact, the transfer of energy occurs from the charged particles to the materials through which they travel. For example, when two similar charges interact, they repel each other, on the other hand when two opposite charges interact they attract each other.

Ionization of Electron

When an incident beam containing high energy electrons falls on the matter, it can transfer a critical amount of energy to an electron present at the inner shell of an atom. The electron present in the atom gains energy and is ejected by ionizing energy provided by the incident electron to a higher energy level. When this excited electron loses its energy again, it will fall to the lower energy level emitting light energy in the form of scintillations.

Summary

Conclusively, an atom contains three charged subatomic particles: electron, proton, and neutron. Later, by various discoveries, the structure of the atom was defined. An atom consists of a positively charged proton and uncharged neutron at the centre, making it a positively charged nucleus and electrons revolving around the nucleus in their respective orbits like the Solar System. Each electron revolving around the nucleus in the fixed orbit has a discrete amount of energy; this makes an atom more stable. The charge of an electron is \( – 1.602 \times {10^{ – 19}}\) and that of a proton is almost like an electron numerically but positively charged. Electrons are the lightest subatomic particles, and the maximum mass of an atom is confined to its nucleus, where protons and neutrons are present.

FAQs on Charged Particles in Matter

Q.1. What are charged particles called?
Ans: A charged particle is called an ion or an atom that consists of an unbalanced number of electrons or protons, making it a negatively charged or positively charged atom.

Q.2. What are the 3 charged particles?
Ans: An atom contains three types of charged subatomic particles: (i) Negatively charged electron, (ii) Positively charged proton, and (iii) uncharged neutron.

Q.3. What happens when a particle is charged?
Ans: When a particle is charged, it becomes negatively charged on gaining electrons or becomes positively charged on releasing electrons. In both cases, when a particle is charged, electrons are transferred.

Q.4. What causes a particle to be charged?
Ans: When particles are excited by imparting energy, they become charged. Mostly, an imbalance of charged particles, i.e., electrons or protons in an atom, causes a particle to be charged.

Q.5. What do you call the positively charged particle?
Ans: A positively charged particle in an atom is known as a proton. The charge of a proton is equal to the charge of an electron in magnitude, but the charge is positive. The hydrogen ion is an example of a proton.

Q.6. Examples of Charged Particles in Matter?
Ans: In an atom, there are three fundamental charged particles: Electrons, Protons, and Neutrons. They are also known as subatomic particles.

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