Atomic structure is the structure of an atom that consists of a nucleus at the center containing neutrons and protons, while electrons revolve around the nucleus. Atoms are made up of a very tiny, positively charged nucleus that is surrounded by a cloud of negatively charged electrons.
The earliest concept of atoms was given by Indian philosopher Maharshi Kanad who proposed that matter is made up of microscopic indestructible particles called 'Parmanu'. A Greek philosopher named Democritus also initially claimed that matter is formed of atoms, and is credited with developing the concepts of atomic structure and quantum mechanics. Later in the 1800s, John Dalton a British Scientist put out the first atomic structure scientific theory.
This article explores the concept of atomic structure in detail, including the atomic models, and the concept of quantum theory.
What is Atomic Structure?
The composition of an element's nucleus and how its electrons are arranged around it are referred to as the element's atomic structure. Protons, electrons, and neutrons comprise the majority of the atomic structure of matter.
The atom's nucleus, which is made up of protons and neutrons, is surrounded by the atom's electrons. The element's atomic number expresses the total number of protons in an element's nucleus. Protons and electrons are equal in number in neutral atoms. But atoms can receive or lose electrons to make them more stable, and the resulting charged object is known as an ion. Because different elements' atoms contain varying numbers of protons and electrons, their atomic structures are also different. This explains why different elements have unique properties.
Atomic Structure Definition
The atomic structure refers to the composition and organization of atoms, the basic units of matter. At the center of an atom is the nucleus, which contains protons (positively charged particles) and neutrons (neutral particles)
The atomic model which we study today was not given at one time. Several attempts were made by scientists and later improved leading to the current atomic model. Let's learn about different atomic models which led to the evolution of the present model.
Atomic Models
Many scientists used atomic models to understand the structure of the atom in the early centuries. Each of these models had advantages and disadvantages of its own and played a significant role in the development of the modern atomic model. Scientists like John Dalton, J.J. Thomson, Ernest Rutherford, and Niels Bohr made the most noteworthy contributions to science.
This section of the article discusses the following theories regarding atomic structure:
- Dalton's Atomic Theory
- Thomson's Atomic Model
- Rutherford's Atomic Model
- Bohr's Atomic Model
- Quantum Mechanical Model
Dalton’s Atomic Theory
John Dalton, a British Chemist proposed that every matter is made up of atoms. These atoms are indivisible and indestructible i.e. they can't be broken down into smaller particles. He also suggested that all atoms of a particular matter are the same, but atoms of different elements differ in size and mass. This means atoms of each element are unique.
According to Dalton’s atomic theory, Chemical reactions occur at atomic level and involve the rearrangements of atoms in order to form the products. According to the postulates proposed in his theory, atomic structure is made up of atoms and they are the smallest particles responsible for chemical reactions to occur.
Postulates of Dalton’s Atomic Theory
- Every matter that exists is made of atoms.
- Atoms are indivisible.
- A particular element has only one type of atom in it.
- Atoms of different elements differ in size and mass.
- An atom has a constant mass that varies for every element.
- During a chemical reaction, atoms undergo rearrangement.
- Atoms can neither be created nor destroyed but can only be transformed from one form to another.
Dalton’s atomic theory was able to explain the Laws of chemical reactions successfully, named the Law of conservation of mass, Law of constant properties, Law of multiple proportions, and Law of reciprocal proportions.
Demerits of Dalton’s Atomic Theory
- This theory was not able to explain the existence of isotopes and isobars.
- No appropriate explanation was provided regarding the structure of atoms.
- Later the atoms were found to be divisible, and Dalton’s claim of atoms being indivisible was proved to be wrong.
The discovery of constituting particles of atoms led to a better understanding of chemicals, these constituting particles are called subatomic particles.
Thomson’s Atomic Model
Sir Joseph John Thomson was also an English chemist famous for his discovery of electrons known as Thomson's Atomic Model, for which he also got the Nobel Prize. He conducted a cathode ray experiment to invent electrons. He proposed that atoms are like a sphere of positive charge with negative charge embedded in them. He named this atomic model as Plum Pudding Model.
Cathode Ray Experiment
In this experiment, a glass tube with two openings is taken. One opening is for the vacuum pump and the other is for intake through which the gas to be filled in the tube is pushed in. Using the vacuum pump a partial vacuum pump is maintained inside the glass chamber. In simple words, a cathode and anode are placed inside the glass tube. The anode is perforated and a photosensitive foil made up of Zinc Sulfide is placed behind it. When high voltage is applied a ray originates from the cathode and moves towards the anode making a spot on Zinc Sulfide foil.
Observations of Cathode Ray Experiment
The following observations were made when the current was allowed to flow between the cathode and anode.
- When the high voltage power is connected and switched ON, rays were transmitted from the cathode towards the anode. Fluorescent spots were observed on the ZnS screen and it confirmed the fact the rays were being transmitted. These rays were given the name Cathode Rays.
- When an external electric field was projected on the tube, the rays got deviated toward the positive electrode. But in the absence of the electric field, the rays got back in a straight line.
- But when rotor blades were fixed in the path of the cathode rays, the rays seemed to rotate. This proved that cathode rays were made of particles that had some mass in them.
- Using all the evidence, Thomson reached the conclusion that cathode rays are composed of negatively charged particles called electrons.
- By applying electric and magnetic fields on the cathode ray, the charge-to-mass ratio (e/m) was found. The e/m for electrons came out to be 17588 × 1011 e/bg
Discovery of Electron
After performing the Cathode Ray Experiment, JJ Thomson explained that the rays that were originating from Cathode and moving towards Anode consists of negatively charged particles called Electron. He further stated that the presence of these negatively charged particles is not limited to specific matters but will be present in every matter irrespective of mass and property. The discovery of the Electron was done in 1897.
Mullikin did an oil-drop experiment to find the charge of the electron using the e/m ratio. He found the charge of the electron = 1.6 x 10-16 C and the Mass of the Electron = 9.1093 × 10-31 kg.
Plum Pudding Model
After Thomson discovered Electron he attempted to describe the structure of the atom. He postulated that an atom is a positively charged sphere in which negatively charged electrons were embedded. The popular name given to this model is the “plum pudding model” because it can be observed as a plum pudding dish where the positively charged atom signifies the pudding and the plum pieces stand for the electrons. Plum Pudding Model is also sometimes referred to as the Watermelon Model where the red edible part of a watermelon is a sphere of positive charge while the seeds of the watermelon are referred to as negatively charged electrons.
Drawbacks of Thomson's Atomic Model
The main drawback of Thomson’s model is that this model is not clear about the stability of an atom. This model could not adjust to other subatomic particles discovered in the future.
Rutherford Atomic Model
Rutherford who was a student of J. J. Thomson discovered Nucleus which contained protons and neutrons inside it. This discovery made huge changes to the atomic structure. The observations made by Thomson in his experiment were used by Rutherford to propose his theory for atomic structure through an experiment called Rutherford's Alpha Ray Scattering Experiment.
Alpha Ray Scattering Experiment
Rutherford used the radioactivity phenomenon in conducting his experiment. He used the radioactive material radium bromide (RaBr). RaBr emits α particles which is a form of radiation. A thin gold metal sheet was put up in the setup. Then the alpha 'α' particles were bombarded on this sheet. The α particle has a charge of +2. To observe the deflection of the particles a screen of Zinc Sulfide (ZnS) was used and placed behind the Gold foil. Rutherford further developed a detector in order to count the number of radioactive particles. Initially, he recorded the count rate of RaBr as he kept a count of α particles emitted per minute.
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Observation of Alpha Ray Scattering Experiment
Following observations were made by Rutherford and conclusions were drawn:
- Most of the α particles passed through thin sheets. This means most of the atom’s space is empty.
- Another observation made was that some of the α particles deflected a bit in every direction. This leads to the conclusion that the positive charge is not distributed uniformly throughout the atom.
- Very few α particles get deflected back along the path that they were traveling on. This happened because of charges repelling each other. Seeing this Rutherford concluded that the positive charge in an atom exists in a very small volume.
- Not only the positively charged particles but a lot of mass is also concentrated in a very small volume. Rutherford named this region as Nucleus.
- Rutherford also came up with the argument that electrons are present in orbits around the orbits, much like the planets in the solar system. Electrons are negatively charged and they revolve around the nucleus.
- The electrons and nucleus are held by the electrostatic force of attraction because they are negatively and positively charged respectively.
Conclusion of Rutherford’s model
Drawing conclusions from all the above observations, Rutherford proposed his Atomic structure which had the following properties -
- The nucleus lies at the center of the atom, and the maximum of the charge and mass is concentrated there only.
- Atoms are spherical in nature.
- Electrons revolve around the nucleus in a circular orbit.
Discovery of Nucleus
In Gold Foil Alpha Particle Experiment, Rutherford observed that most of the spaces inside an atom are vacant and there is a small dense region located at the center inside the atom. He termed this region as Nucleus and said that this Nucleus is positively charged and most of the masses of the atom are concentrated in Nucleus only.
Limitations of Rutherford Atomic Model
Just like other atomic models, Rutherford’s model also had many shortcomings.
- Since electrons revolve in a circular orbit around the nucleus in an atom it is an accelerated motion. As per Electromagnetic Theory when a charged particle is in accelerated motion it loses energy. Hence, electrons will spend a lot of energy and eventually, they will lose the entire energy and the atom will collapse. This raises serious questions about the stability of the atom.
- Rutherford didn't say anything about the position of electrons whether all electrons be in the same or different orbits and the reason behind it.
- If the electrons are revolving continuously around the nucleus, then the spectrum that they emit should be a continuous spectrum, but what we observe is a line spectrum.
Bohr’s Atomic Model
Neils Bohr, a student of Rutherford proposed his model in 1915 to address the limitation of Rutherford's Atomic Model. It is the most widely used atomic model and is based on Planck’s theory of quantization. It explains that electrons always move in fixed orbitals only, and they are not present everywhere in the atom. Bohr also explained that each orbit has a fixed energy level. An orbit is also called an Energy Shell. Rutherford only explained the nucleus of the atom while Bohr made changes to that model and added electrons and energy levels.
As per Bohr’s model, inside an atom, there is a small nucleus that is positively charged and is surrounded by negative electrons which move around in orbits which has specific energy level. To revolve in a particular orbit, electrons must possess energy equal to the energy level of the shell. Bohr found out that the larger the distance of an electron from the nucleus, the larger its energy which means the orbits near the nucleus has smaller energy and the shell farthest from the nucleus has larger energy.
Postulates of Bohr’s Atomic Theory
- Inside atoms, electrons are present in discrete orbits called “stationary orbits”.
- Quantum numbers are used to represent the energy levels of these shells.
- Electrons can go to higher levels by absorbing energy and move to lower energy levels by losing or emitting some energy.
- When an electron stays in its own orbit, no absorption or emission of energy takes place.
- Electrons revolve in these stationary orbits only.
- The energy of the stationary orbits is quantized.
Limitations of Bohr’s Atomic Theory
- It works only for single-electron species such as H, He+, Li2+, and Be3+
- When a more accurate spectrometer was used to observe the emission spectrum of hydrogen, each line spectrum was seen to be a combination of multiple smaller discrete lines.
- Bohr’s theory was unable to explain Stark and Zeeman's effects.
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Quantum Mechanical Model of Atom
Quantum Mechanics is the branch of physics that deals with the motion and kinematics of microscopic objects. Since atoms are of below microscopic size and the limitations of Bohr's Atomic Model motivated the scientists to give a more general and accurate atomic model based on Quantum Theory. The Quantum Mechanical Model of the Atom basically uses two following theories to explain the structure of the atom:
- Dual Behaviour of Matter
- Heisenberg Uncertainty Principle
Dual Behaviour of Matter
Dual Behaviour of Matter was proposed by French physicist de-Broglie. He stated that every matter irrespective of its size exhibits both wave-like properties and particle-like properties. He meant to say that just like a photon has both wavelength and momentum similarly an electron will have both wavelength(λ) and momentum(p). He called these waves Matter Waves. The relation between wavelength and momentum is given by
λ = h/p
where,
- λ is Wavelength
- p is Momentum
- h is Planck's Constant
Heisenberg Uncertainty Principle
Heisenberg's Uncertainty Principle states that when a microscopic particle is in motion it is impossible to find the exact position and momentum of the particle simultaneously. He meant that at a time we can find either position or momentum i.e. if the exact position is known then momentum is uncertain and vice-versa. It is represented as
Δx.Δp ≥ h/4π
where,
- Δx is Uncertainty in Position
- Δp is Uncertainty in Momentum
- h is Planck's Constant
From the formula, it means that if Δ for the position is very small i.e. if the position is known exactly then Δp will be very large hence, physically we will have a blurred image of the measurement. Hence, it talks about probability which is the basis of the Quantum Mechanical Model of Atom.
Although the above two concepts are important for understanding of Quantum Mechanical Model of Atom, it is equally important to know the Schrodinger Wave Equation which was the most fundamental equation of Quantum Mechanics related to the energy of the system.
Schrodinger Wave Equation
Schrodinger Wave Equation gives the equation for the total energy of the system (an atom or a molecule) whose energy doesn't change with time i.e. there is no loss or gain of energy. Mathematically, Schrodinger Wave Equation is represented as
Hψ = Eψ
where
- H is Hamiltonian Operator in Mathematics
- E is the Total Energy of the System
- ψ is a Wave function
The solution of the Schrodinger Wave Equation gives the value of E and ψ.
Postulates of Quantum Mechanical Model of Atom
Quantum Mechanical Model states the following about structure of the atom
- The energy of electrons in atoms is quantized i.e. energy level of an electron is an integral multiple of the smallest energy quantity.
- Quantized Energy levels exist due to Wave like Properties of electrons and their solution can be given by Schrodinger Wave Equation.
- Since it is impossible to find the position and momentum of an electron simultaneously therefore we talk about the probability of different physical points related to the electron.
- Atomic Orbital of an atom is represented by wave function ψ. Each orbital can be occupied by two electrons at maximum. When an electron occupies an orbital it is represented by ψ.
- Quantum Model states that there is an electron cloud around the nucleus inside an atom. The probability to find an electron inside an atom is given by |ψ|2, which is called Probability Distribution Function.
Quantum Number
To describe the location of an electron inside an atom we need a set of 4 numbers known as Quantum Numbers. These Quantum Number helps in distinguishing different orbitals which contain electron. Orbitals that have a smaller number mean they are closer to the nucleus, have a smaller size, and have a larger probability of finding an electron. The four types of Quantum Numbers are listed below:
- Principal Quantum Number
- Azimuthal Quantum Number
- Magnetic Quantum Number
- Spin Quantum Number
Principal Quantum Number(n)
It is represented by 'n'. It gives the idea of a shell in which an electron is present and also about its energy. A lower value of 'n' means the shell is closer to the nucleus and has lower energy. It is given by n = 1,2,3...
Azimuthal Quantum Number(l)
It is represented by 'l'. It gives an idea of the subshell and 3D shape of the orbital. The subshells are given as s, p, d, and f. The value assigned to subshells are 0 = s, 1 = p, 2 = d, 3 = f. A shell contains 0 to n-1 subshell. For Example, the third shell i.e. n = 3 will have 0 to (3-1) subshells i.e. 0 to 2 subshells which include 0,1 and 2.
| n | l | Subshell Notation |
|---|
| 1 | 0 | 1s |
| 2 | 0 | 2s |
| 2 | 1 | 2p |
| 3 | 0 | 3s |
| 3 | 1 | 3p |
| 3 | 2 | 3d |
Magnetic Quantum Number(ml)
It is represented by ml. It gives an idea of the orientation of orbital in space with respect to coordinate axes. A subshell contains -l to l orbitals. For Example, subshell p contains -1 to 1 orbital i.e. -1, 0, 1, a total of three orbitals oriented along different coordinate axes and coordinate planes.
Spin Quantum Number(ms)
It is represented by ms. It gives an idea about the spinning or orientation of electrons. It takes the value of +1/2 or -1/2. If ms is +1/2 it means the electron is rotating clockwise and is represented as ⇡ while if ms is -1/2 it means the electron is rotating anticlockwise and is represented as ⇣.
As of now, we have learned all the atomic models, now we will look at the properties of all the subatomic particles.
Subatomic Particles
The subatomic particles are the particles that are present inside the atom, There are three subatomic particles that are,
Protons
- Protons have a positive charge. This charge is 1e, which is approximately 1.602 × 10-19
- Mass of a proton is approximately 1.672 × 10-24
- Protons are over 1800 times heavier than electrons.
- Total number of protons in the atoms of an element and the atomic number of the element is always equal.
Neutrons
- Mass of a neutron is almost similar to that of a proton i.e. 1.674 × 10-24
- Neutrons are always electrically neutral particles and do not carry any charge.
- Isotopes of an element have the same number of protons but a different number of protons in their respective nuclei.
Electrons
- Charge of an electron is -1e, which is approximately -1.602 × 10-19
- Mass of an electron is approximately 9.1 × 10-31.
- Mass of an electron is almost negligible as compared to the mass of an atom, so an electron's mass is ignored while calculating the mass of an atom.
Isotopes
Isotopes are the atoms of same elements that have the same atomic number but different mass numbers. Example C-12, C-13 and C-14. Here all are Carbon atoms and have the same atomic number i.e. 6 but different mass numbers. This difference in mass numbers can be understood from their atomic structure.
Atomic Structure of Isotopes
The isotopes of an atom have the same atomic number which means that the number of protons are same. Also, their chemical properties are the same because their electronic configuration is the same. The difference in mass number arises due to the difference in number of neutrons present inside the nucleus. Hence, the atomic structure of isotopes comprises of the same number of electrons and protons but different number of neutrons. We can understand this with the example of isotopes of hydrogen illustrated below:
To describe the structure of an isotope, the element's symbol is used along with the atomic number and the mass number of the isotope. To give an example, Hydrogen has 3 isotopes named protium, deuterium, and tritium. The atomic configuration of three isotopes of hydrogen is tabulated below:
| Isotopes of Hydrogen | Atomic Number | Mass Number | No. of Electrons | No. of Protons | No. of Neutrons |
|---|
| Protium | 1 | 1 | 1 | 1 | 0 |
|---|
| Deuterium | 1 | 2 | 1 | 1 | 1 |
|---|
| Tritium | 1 | 3 | 1 | 1 | 2 |
|---|
The stability of isotopes is different. The half-lives are also different. But they generally have similar chemical behavior because they have the same electronic structures. The pictorial representation of isotopes of hydrogen can be seen below:
Electronic Configuration of Elements
The Electronic Configuration of Elements refers to the arrangement of electrons in different energy levels. The rule for the arrangement of electrons is governed by the following three laws:
Aufbau Principle
Aufbau is a German word that means 'to build'. In Chemistry, Aufbau Principle states that the electronic arrangement of an element is done by filling electrons in ascending order of energy of subshell. It means electrons first enter subshells of lower energy and then of higher energy levels. The energy of a subshell is determined by adding Principal Quantum Number and Azimuthal Quantum Number i.e. (n+l). If two subshells have the same (n+l) value then the subshell having a lower value of n is of lower energy. Hence, electrons enter in the order of 1s, 2s, 2p, 3s, 3p, 4s, and 3d.....
Hund's Rule
Hund's Rule states that electrons in the subshell in the manner that in the first attempt of filling the subshell is half-filled i.e. each orbital has one electron and then the pairing of electrons is done. This is because half-filled and full-filled orbitals are more stable than incompletely-filled orbitals.
Pauli Exclusion Principle
Pauli Exclusion Principle states that an orbital can have a maximum of two electrons with opposite spin. This is because if two electrons of the same spin are in an orbital then all four quantum numbers will be the same which is not possible as per the Quantum Mechanical Model of the atom.
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Summary - Atomic Structure
- Atom: The defining structure and basic units of matter of an element are called atoms. The term "atom" came from a Greek word that means indivisible because earlier atom was thought to be the smallest things in the universe that could not be divided
- Atomic Structure: The structure of an atom comprising a nucleus, in which the protons and neutrons are present. The negatively charged particles called electrons revolve around the center of the nucleus.
- Nucleus: A collection of particles called protons and neutrons is called Nucleus. Protons are positively charged and neutrons, are electrically neutral. Protons and neutrons are made up of particles called quarks. The chemical element of an atom is determined by the number of protons, or the atomic number, Z, of the nucleus.
- Proton: Positively charged particles found within atomic nuclei are given the name Proton. Rutherford discovered the proton in his famous cathode ray experiment that was conducted between 1911 and 1919. Protons are about 99.86% as massive as neutrons. The number of protons in an atom is unique for each element
- Electron: Electrons are very tiny compared to protons and neutrons, about 1800 times smaller than either a proton or a neutron. Electrons are just 0.054% as massive as neutrons. Electrons were discovered in 1897 by Joseph John (J.J.) Thomson, a British physicist. Electrons have a negative charge and are electrically attracted to the positively charged protons
- Neutron: Rutherford theorized the neutron's existence in 1920 and was later discovered by Chadwick in 1932. Neutrons were found during experiments where atoms were shot at a thin sheet of beryllium. Subatomic particles with no charge were released – and were named neutrons. Neutrons are uncharged particles found within all atomic nuclei
- Isotopes: Members of the same family of an element that all have the same number of protons but different numbers of neutrons are named isotopes. The number of protons in a nucleus determines the element's atomic number on the Periodic Table. All the isotopes have unique properties, just like all family members have their own qualities.
Atomic Structure Class 11
The study of atomic structure in Class 11 (part of high school curriculum in many countries) introduces fundamental concepts that lay the groundwork for understanding chemistry and physics at a deeper level. These topics are not only foundational for Class 11 students but also essential for anyone studying chemistry or physics, providing a base for more complex topics in these and related fields.
Understanding atomic structure allows students to grasp the nature of chemical reactions, the properties of elements and compounds, and the behavior of materials at the molecular and atomic levels.
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TorqueTorque is the effect of force when it is applied to an object containing a pivot point or the axis of rotation (the point at which an object rotates), which results in the form of rotational motion of the object. The Force causes objects to accelerate in the linear direction in which the force is ap
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Angular MomentumAngular Momentum is a kinematic characteristic of a system with one or more point masses. Angular momentum is sometimes called Rotational Momentum or Moment of Momentum, which is the rotational equivalent of linear momentum. It is an important physical quantity as it is conserved for a closed system
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Centre of MassCentre of Mass is the point of anybody where all the mass of the body is concentrated. For the sake of convenience in Newtonian Physics, we take the body as the point object where all its mass is concentrated at the centre of mass of the body. The centre of mass of the body is a point that can be on
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Centre of GravityCentre of Gravity is one of the fundamental concepts in the study of gravitational force. Engineers and Scientists while dealing with mechanics and gravity often come across solid bodies which can't be represented by point masses such as celestial objects. In those cases, it is assumed as well as pr
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Radius of GyrationRadius of gyration, R, is a measure used in mechanics and engineering to describe the distribution of mass or inertia of an object relative to its axis of rotation. Radius of Gyration, or the radius of a body, is always centered on its rotational axis. It is a geometric characteristic of a rigid bod
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Moment of InertiaMoment of Inertia is a property of a body in rotational motion that resists changes in its rotational state. It is analogous to mass (inertia) in linear motion. Mathematically, it is defined as the sum of the product of each particle’s mass and the square of its distance from the axis of rotation: I
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Fluid Mechanics
Mechanical Properties of FluidsFluids are substances that can flow and adapt to the shape of their container, including liquids and gases like water and air. Mechanical properties of fluids refer to viscosity, density, and pressure, which describe how fluids respond to external forces and influence their behavior in various situa
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What is Viscosity?Viscosity is a fundamental property of liquids that describes their internal resistance to flow. Imagine three bowls—one filled with water and the other with oil and honey. If you were to tip the three bowls and observe the flow, you’d quickly notice that water pours out much faster than oil and hon
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Buoyant ForceBuoyancy is a phenomenon due to the buoyant force that causes an object to float. When you put an object in a liquid, an upward force is exerted on the object by the liquid. This force is equal to the weight of the liquid that has been displaced. The amount of liquid that has been displaced depends
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Archimedes PrincipleArchimedes Principle is a fundamental concept in fluid mechanics, credited to the ancient Greek mathematician and physicist Archimedes. According to Archimedes' Principle, when an object is immersed in a fluid the object experiences an upward force whose magnitude is equal to the weight of the fluid
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Pascal's LawPascal's law establishes the relation between pressure and the height of static fluids. A static fluid is defined as a fluid that is not in motion. When the fluid is not flowing, it is said to be in hydrostatic equilibrium. For a fluid to be in hydrostatic equilibrium, the net force on the fluid mus
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Reynolds NumberAs liquid runs into a channel, it collides with the pipe. Engineers ensure that the liquid flow through the city's pipes is as consistent as possible. As a result, a number known as the Reynolds number predicts whether the flow of the liquid will be smooth or turbulent. Sir George Stoke was the firs
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Streamline FlowThe substance that can change its form under an external force is defined as fluid. Whenever an external force is applied to a fluid, it begins to flow. The study of fluids in motion is defined as fluid dynamics. Have you ever noticed a creek flowing beneath the bridge? When you see a streamline, wh
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Laminar and Turbulent FlowLaminar flow and turbulent flow describe the movement patterns of fluids. Laminar flow is characterized by smooth, orderly layers of fluid sliding over one another without mixing, ideal for scenarios where minimal resistance is desired. Turbulent flow features chaotic, swirling patterns with irregul
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Bernoulli's PrincipleBernoulli's Principle, formulated by Daniel Bernoulli and later expressed as Bernoulli's Equation by Leonhard Euler in 1752, is a fundamental concept in fluid mechanics. It describes the relationship between the pressure (P), velocity, and height (h) of a fluid in motion. The principle states that i
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Poiseuilles Law FormulaAccording to Poiseuille's law, the flow of liquid varies depending on the length of the tube, the radius of the tube, the pressure gradient and the viscosity of the fluid. It is a physical law that calculates the pressure drop in an incompressible Newtonian fluid flowing in laminar flow through a lo
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Stoke's LawStoke's Law: Observe a raindrop falling from a height if you look closely you will notice that the speed of all the raindrops is constant and even though it falls from a height under the influence of gravity its velocity seems constant. These questions are answered using Stoke's lawStoke's law was f
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Solid Mechanics
What is Stress?Stress in physics is defined as the force exerted on the unit area of a substance. Stress affects the body as strain in which the shape of the body changes if the stress is applied and sometimes it gets permanently deformed. On the basis of the direction of force applied to the body, we can categori
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Stress and StrainStress and Strain are the two terms in Physics that describe the forces causing the deformation of objects. Deformation is known as the change of the shape of an object by applications of force. The object experiences it due to external forces; for example, the forces might be like squeezing, squash
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Stress-Strain CurveStress-Strain Curve is a very crucial concept in the study of material science and engineering. It describes the relationship between stress and the strain applied on an object. We know that stress is the applied force on the material, and strain, is the resulting change (deformation or elongation)
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Elasticity and PlasticityYou've undoubtedly heard of the idea of elasticity by now. In layman's words, it indicates that after being stretched, some substances return to their former form. You've experimented with a slingshot. Didn't you? That is an elastic substance. Let us go into the ideas of elasticity and plasticity to
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Modulus of ElasticityModulus of Elasticity or Elastic Modulus is the measurement of resistance offered by a material against the deformation force acting on it. Modulus of Elasticity is also called Young's Modulus. It is given as the ratio of Stress to Strain. The unit of elastic modulus is megapascal or gigapascal Modu
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Modulus of RigidityModulus of rigidity also known as shear modulus, is used to measure the rigidity of a given body. It is the ratio of shear stress to shear strain and is denoted by G or sometimes by S or μ. The modulus of rigidity of a material is directly proportional to its elastic modulus which depends on the mat
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Young's ModulusYoung's Modulus is the ratio of stress and strain. It is named after the famous British physicist Thomas Young. It is also known as the "Modulus of Elasticity" and is a fundamental property that describes the relationship between stress and strain in elastic materials. It explains how a material def
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Bulk Modulus FormulaThe modulus of elasticity measures a material's resistance to elastic deformation under external forces. Understanding this property is important for designing structures with materials like metals, concrete, and polymers to ensure they can withstand stresses without permanent deformation.The modulu
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Shear Modulus and Bulk ModulusA rigid body model is an idealised representation of an item that does not deform when subjected to external forces. It is extremely beneficial for evaluating mechanical systems—and many physical items are quite stiff. The degree to which an item may be regarded as stiff is determined by the physica
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Poisson's RatioPoisson's Ratio is the negative ratio of transversal strain or lateral strain to the longitudinal strain of a material under stress. When a material particularly a rubber-like material undergoes stress the deformation is not limited to only one direction, rather it happens along both transversal and
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Stress, Strain and Elastic Potential EnergyElasticity, this term always reminds of objects like Rubber bands, etc. However, if the question arises, which one is more elastic- A rubber or an Iron piece? The answer will be an Iron piece. Why? The answer lies in the definition of Elasticity, elasticity is known to be the ability of the object t
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Thermodynamics
Basics Concepts of ThermodynamicsThermodynamics is concerned with the ideas of heat and temperature, as well as the exchange of heat and other forms of energy. The branch of science that is known as thermodynamics is related to the study of various kinds of energy and its interconversion. The behaviour of these quantities is govern
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Zeroth Law of ThermodynamicsZeroth Law of Thermodynamics states that when two bodies are in thermal equilibrium with another third body than the two bodies are also in thermal equilibrium with each other. Ralph H. Fowler developed this law in the 1930s, many years after the first, second, and third laws of thermodynamics had a
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First Law of ThermodynamicsFirst Law of Thermodynamics adaptation of the Law of Conservation of Energy differentiates between three types of energy transfer: Heat, Thermodynamic Work, and Energy associated with matter transfer. It also relates each type of energy transfer to a property of a body's Internal Energy. The First L
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Second Law of ThermodynamicsSecond Law of Thermodynamics defines that heat cannot move from a reservoir of lower temperature to a reservoir of higher temperature in a cyclic process. The second law of thermodynamics deals with transferring heat naturally from a hotter body to a colder body. Second Law of Thermodynamics is one
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Thermodynamic CyclesThermodynamic cycles are used to explain how heat engines, which convert heat into work, operate. A thermodynamic cycle is used to accomplish this. The application determines the kind of cycle that is employed in the engine. The thermodynamic cycle consists of a series of interrelated thermodynamic
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Thermodynamic State Variables and Equation of StateThe branch of thermodynamics deals with the process of heat exchange by the gas or the temperature of the system of the gas. This branch also deals with the flow of heat from one part of the system to another part of the system. For systems that are present in the real world, there are some paramete
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Enthalpy: Definition, Formula and ReactionsEnthalpy is the measurement of heat or energy in the thermodynamic system. It is the most fundamental concept in the branch of thermodynamics. It is denoted by the symbol H. In other words, we can say, Enthalpy is the total heat of the system. Let's know more about Enthalpy in detail below.Enthalpy
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State FunctionsState Functions are the functions that are independent of the path of the function i.e. they are concerned about the final state and not how the state is achieved. State Functions are most used in thermodynamics. In this article, we will learn the definition of state function, what are the state fun
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Carnot EngineA Carnot motor is a hypothetical motor that works on the Carnot cycle. Nicolas Leonard Sadi Carnot fostered the fundamental model for this motor in 1824. In this unmistakable article, you will find out about the Carnot cycle and Carnot Theorem exhaustively. The Carnot motor is a hypothetical thermod
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Heat Engine - Definition, Working, PV Diagram, Efficiency, TypesHeat engines are devices that turn heat energy into motion or mechanical work. Heat engines are based on the principles of thermodynamics, specifically the conversion of heat into work according to the first and second laws of thermodynamics. They are found everywhere, from our cars, power plants to
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Wave and Oscillation
Introduction to Waves - Definition, Types, PropertiesA wave is a propagating dynamic disturbance (change from equilibrium) of one or more quantities in physics, mathematics, and related subjects, commonly described by a wave equation. At least two field quantities in the wave medium are involved in physical waves. Periodic waves occur when variables o
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Wave MotionWave Motion refers to the transfer of energy and momentum from one point to another in a medium without actually transporting matter between the two points. Wave motion is a kind of disturbance from place to place. Wave can travel in solid medium, liquid medium, gas medium, and in a vacuum. Sound wa
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OscillationOscillations are defined as the process of repeating vibrations of any quantity about its equilibrium position. The word “oscillation†originates from the Latin verb, which means to swing. An object oscillates whenever a force pushes or pulls it back toward its central point after displacement. This
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Oscillatory Motion FormulaOscillatory Motion is a form of motion in which an item travels over a spot repeatedly. The optimum situation can be attained in a total vacuum since there will be no air to halt the item in oscillatory motion friction. Let's look at a pendulum as shown below. The vibrating of strings and the moveme
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Amplitude FormulaThe largest deviation of a variable from its mean value is referred to as amplitude. It is the largest displacement from a particle's mean location in to and fro motion around a mean position. Periodic pressure variations, periodic current or voltage variations, periodic variations in electric or ma
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What is Frequency?Frequency is the rate at which the repetitive event that occurs over a specific period. Frequency shows the oscillations of waves, operation of electrical circuits and the recognition of sound. The frequency is the basic concept for different fields from physics and engineering to music and many mor
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Amplitude, Time Period and Frequency of a VibrationSound is a form of energy generated by vibrating bodies. Its spread necessitates the use of a medium. As a result, sound cannot travel in a vacuum because there is no material to transfer sound waves. Sound vibration is the back and forth motion of an entity that causes the sound to be made. That is
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Energy of a Wave FormulaWave energy, often referred to as the energy carried by waves, encompasses both the kinetic energy of their motion and the potential energy stored within their amplitude or frequency. This energy is not only essential for natural processes like ocean currents and seismic waves but also holds signifi
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Simple Harmonic MotionSimple Harmonic Motion is a fundament concept in the study of motion, especially oscillatory motion; which helps us understand many physical phenomena around like how strings produce pleasing sounds in a musical instrument such as the sitar, guitar, violin, etc., and also, how vibrations in the memb
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Displacement in Simple Harmonic MotionThe Oscillatory Motion has a big part to play in the world of Physics. Oscillatory motions are said to be harmonic if the displacement of the oscillatory body can be expressed as a function of sine or cosine of an angle depending upon time. In Harmonic Oscillations, the limits of oscillations on eit
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Sound
Production and Propagation of SoundHave you ever wonder how are we able to hear different sounds produced around us. How are these sounds produced? Or how a single instrument can produce a wide variety of sounds? Also, why do astronauts communicate in sign languages in outer space? A sound is a form of energy that helps in hearing to
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What are the Characteristics of Sound Waves?Sound is nothing but the vibrations (a form of energy) that propagates in the form of waves through a certain medium. Different types of medium affect the properties of the wave differently. Does this mean that Sound will not travel if the medium does not exist? Correct. It will not, It is impossibl
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Speed of SoundSpeed of Sound as the name suggests is the speed of the sound in any medium. We know that sound is a form of energy that is caused due to the vibration of the particles and sound travels in the form of waves. A wave is a vibratory disturbance that transfers energy from one point to another point wit
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Reflection of SoundReflection of Sound is the phenomenon of striking of sound with a barrier and bouncing back in the same medium. It is the most common phenomenon observed by us in our daily life. Let's take an example, suppose we are sitting in an empty hall and talking to a person we hear an echo sound which is cre
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Refraction of SoundA sound is a vibration that travels as a mechanical wave across a medium. It can spread via a solid, a liquid, or a gas as the medium. In solids, sound travels the quickest, comparatively more slowly in liquids, and the slowest in gases. A sound wave is a pattern of disturbance caused by energy trav
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How do we hear?Sound is produced from a vibrating object or the organ in the form of vibrations which is called propagation of sound and these vibrations have to be recognized by the brain to interpret the meaning which is possible only in the presence of a multi-functioning organ that is the ear which plays a hug
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Audible and Inaudible SoundsWe hear sound whenever we talk, listen to some music, or play any musical instrument, etc. But did you ever wondered what is that sound and how is it produced? Or why do we hear to our own voice when we shout in a big empty room loudly? What are the ranges of sound that we can hear? In this article,
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Explain the Working and Application of SONARSound energy is the type of energy that allows our ears to sense something. When a body vibrates or moves in a ‘to-and-fro' motion, a sound is made. Sound needs a medium to flow through in order to propagate. This medium could be in the form of a gas, a liquid, or a solid. Sound propagates through a
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Noise PollutionNoise pollution is the pollution caused by sound which results in various problems for Humans. A sound is a form of energy that enables us to hear. We hear the sound from the frequency range of 20 to 20000 Hertz (20kHz). Humans have a fixed range for which comfortably hear a sound if we are exposed
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Doppler Effect - Definition, Formula, ExamplesDoppler Effect is an important phenomenon when it comes to waves. This phenomenon has applications in a lot of fields of science. From nature's physical process to planetary motion, this effect comes into play wherever there are waves and the objects are traveling with respect to the wave. In the re
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Doppler Shift FormulaWhen it comes to sound propagation, the Doppler Shift is the shift in pitch of a source as it travels. The frequency seems to grow as the source approaches the listener and decreases as the origin fades away from the ear. When the source is going toward the listener, its velocity is positive; when i
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Electrostatics
ElectrostaticsElectrostatics is the study of electric charges that are fixed. It includes an study of the forces that exist between charges as defined by Coulomb's Law. The following concepts are involved in electrostatics: Electric charge, electric field, and electrostatic force.Electrostatic forces are non cont
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Electric ChargeElectric Charge is the basic property of a matter that causes the matter to experience a force when placed in a electromagnetic field. It is the amount of electric energy that is used for various purposes. Electric charges are categorized into two types, that are, Positive ChargeNegative ChargePosit
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Coulomb's LawCoulomb’s Law is defined as a mathematical concept that defines the electric force between charged objects. Columb's Law states that the force between any two charged particles is directly proportional to the product of the charge but is inversely proportional to the square of the distance between t
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Electric DipoleAn electric dipole is defined as a pair of equal and opposite electric charges that are separated, by a small distance. An example of an electric dipole includes two atoms separated by small distances. The magnitude of the electric dipole is obtained by taking the product of either of the charge and
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Dipole MomentTwo small charges (equal and opposite in nature) when placed at small distances behave as a system and are called as Electric Dipole. Now, electric dipole movement is defined as the product of either charge with the distance between them. Electric dipole movement is helpful in determining the symmet
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Electrostatic PotentialElectrostatic potential refers to the amount of electrical potential energy present at a specific point in space due to the presence of electric charges. It represents how much work would be done to move a unit of positive charge from infinity to that point without causing any acceleration. The unit
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Electric Potential EnergyElectrical potential energy is the cumulative effect of the position and configuration of a charged object and its neighboring charges. The electric potential energy of a charged object governs its motion in the local electric field.Sometimes electrical potential energy is confused with electric pot
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Potential due to an Electric DipoleThe potential due to an electric dipole at a point in space is the electric potential energy per unit charge that a test charge would experience at that point due to the dipole. An electric potential is the amount of work needed to move a unit of positive charge from a reference point to a specific
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Equipotential SurfacesWhen an external force acts to do work, moving a body from a point to another against a force like spring force or gravitational force, that work gets collected or stores as the potential energy of the body. When the external force is excluded, the body moves, gaining the kinetic energy and losing a
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Capacitor and CapacitanceCapacitor and Capacitance are related to each other as capacitance is nothing but the ability to store the charge of the capacitor. Capacitors are essential components in electronic circuits that store electrical energy in the form of an electric charge. They are widely used in various applications,
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