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Chapter 2 – Structure of Atom

The following Topics and Sub-Topics are covered in this chapter and are available on MSVgo:

Introduction

The structure of atom is one of the most basic concepts in Chemistry that you need to memorize moving forward. An atom consists of a nucleus with protons and neutrons in it, while the electrons, which are negatively charged particles, spin around the centre of the nucleus. In this article, we are discussing the structure of atoms and the corresponding atomic theories to help you understand the basics.

Several scientists tried to describe the structure of the atom through atomic models during the 18th and 19th centuries. There were many advantages and disadvantages of these atomic models. However, they played a crucial role in the evolution of the modern atomic model. Let’s learn how.

John Dalton, an English chemist, put forth that all matters are made up of atoms, which are invisible and unbreakable. The postulates of Dalton’s Atomic Theory are:

  • Atoms are made up of matter.
  • Atoms are invisible.
  • Only one type of atom is present in specific elements.
  • The constant mass of each atom varies from element to element. 
  • In the course of chemical reaction atoms experience rearrangement. 
  • These atoms can be modified but cannot be created nor can be destroyed.

Sir Joseph John Thomson conducted an experiment called the cathode ray experiment. He realized that through the experiment you can define the atomic structure as a positively charged sphere having negatively charged electrons in it. Thomson used a tube made of glass with two openings through which you can pump in the gas and another a vacuum pump to get the gas out. According to Thomson, atoms are electrically neutral as positive and negative charges have equal magnitude.

The limitation of the Thomson Atomic Model is that it failed to explain clearly the stability of an atom and that other subatomic particles cannot be deposited inside this model.

Rutherford altered the atomic structure with the discovery of subatomic particles called the nucleus. His experiment employed Alpha ray scattering. His observations were:

  • The space inside the atom is empty. 
  • Due to repulsion, some rays get reflected as well, and because of the strong positive charge in the centre of the atom, 1/1000th rays got strongly deflected.  
  • The nucleus is occupied by the charge and mass of the atom.
  • If electrons spend energy while revolving around the nucleus, then it will lose all their energy; thus, the stability of the atom is not described.
  • If electrons revolve around the nucleus, then it will be a continuous spectrum. But in actuality, it is a line spectrum.

The Subatomic particles include:

  • Protons: They are positively charged subatomic particles having a 1e charge and mass of roughly 1.672 × 10-24.
  • Neutrons:  The mass of neutrons is nearly the same as that of a proton, i.e. 1.674×10-24. Neutrons carry no charge and are electrically neutral particles.
  • Electrons: It carries a charge of -1e and mass roughly 9.1 × 10-31. Electrons are disregarded while calculating the mass of an atom because of their relatively negligible mass.

Nucleons are the part of the nucleus of an atom. You can consider a nucleon as both a proton or a neutron. Atomic numbers illuminate the unique number of protons present in an element. However, an element’s atomic structure can differ in the total number of nucleons.

The variation of elements having different nucleon numbers is called isotopes of the elements. So if you find an element having the same number of protons but the number of neutrons being different then that will be an isotope of an element.

According to this theory proposed by Niels Bohr and Ernest Rutherford: 

  • The electrons inside atoms are placed in discrete orbits called stationary orbits.
  • Quantum numbers represent the energy level of these cells.
  • Electrons tend to jump to higher levels by absorbing energy and vice versa.
  • Electrons spin around the nucleus in these stationary orbits only. 
  • Stationary orbits energy is quantified.

Thomas Young was the first to prove that electrons have a photoelectric effect which states that they also have wave nature. He showed that through an experiment called the double-slit experiment.

1. Who discovered the structure of the atom?

Answer: Democritus was the first to propose the concept of atoms, but the idea of atomic theory was revived by John Dalton.

2. What is the atomic structure in physics?

Answer: It is a complex arrangement of negatively charged electrons put in shells about a positively charged nucleus. Atom’s mass which is made up of protons and neutrons is the content of the nucleus. Neutrons proved to help understand the structure of an atom.

3. Who found Neutron?

Answer:- British physicist James Chadwick, discovered neutrons in 1932.

4. Who discovered the electron?

Answer:- In 1897, British physicist J.J. Thomson discovered electrons.

The study of the structure of atom has greatly aided in understanding the whole class of chemical reactions, bonds, and their physical properties. Therefore, it is crucial to learn the core concept behind the structure of atom. To learn more about it, check out the MSVgo app and their official site. The MSVgo philosophy is to enable a core understanding of any concept. The video library of the app explains concepts with examples or explanatory visualisations or animations., Happy learning.

High School Physics

  • Alternating Current
  • Atoms
  • Communication Systems
  • Current Electricity
  • Dual nature of Radiation and Matter
  • Electric Charges and Fields
  • Electricity
  • Electromagnetic Induction
  • Electromagnetic Waves
  • Electron Beams and Radioactivity
  • Electrons and Photons
  • Electrostatic Potential and Capacitance
  • Fluid Pressure
  • Force and Acceleration
  • Force And Laws Of Motion
  • Gravitation
  • Internal Energy
  • Kinetic Theory
  • Law of motion
  • Light – Reflection And Refraction
  • Magnetic Effects Of Electric Current
  • Magnetism and Matter
  • Management Of Natural Resources
  • Mechanical properties of Fluids
  • Mechanical properties of Solids
  • Motion
  • Motion in a plane
  • Motion in a straight line
  • Moving Charges and Magnetism
  • Nuclear Energy
  • Nuclei
  • Oscillations
  • Our Environment
  • Paths of Heat
  • Physical world
  • Ray optics and optical instruments
  • Semiconductor Devices
  • Semiconductor Electronics: Materials, Devices and Simple Circuits
  • Simple Machines
  • Sound
  • Sources Of Energy
  • Specific and Latent Heats
  • Spherical Mirrors
  • Static Electricity
  • Systems of Particles and Rotational motion
  • Thermal properties of matter
  • Thermodynamics
  • Units and Measurement
  • Vectors, Scalar Quantities and Elementary Calculus
  • Wave Optics
  • Waves
  • Work, Power and Energy

High School Chemistry

  • Acids, Bases and Salts
  • Alcohols, Phenols and Ethers
  • Aldehydes, Ketones and Carboxylic Acids
  • Aliphatic and Aromatic Hydrocarbons
  • Alkyl and Aryl Halides
  • Amines
  • Analytical Chemistry 
  • Atomic Structure
  • Atoms And Molecules
  • Basic concepts of Chemistry
  • Biomolecules
  • Carbon And Its Compounds
  • Carboxylic acids and Acid Derivatives
  • Chemical Bonding and Molecular Structures
  • Chemical Energetics
  • Chemical Equilibria
  • Chemical Kinetics
  • Chemical Reactions And Equations
  • Chemical Reactions and Their Mechanisms
  • Chemistry in Everyday Life
  • Chemistry of p-Block elements
  • Chemistry of Transition and Inner Transition
  • Classification of Elements
  • Coordination Compounds
  • Cyanide, Isocyanide, Nitro compounds and Amines
  • Electrochemistry
  • Electrolysis
  • Elements, Compounds and Mixtures
  • Environmental Chemistry
  • Equilibrium
  • Ethers and Carbonyl compounds
  • Haloalkanes and Haloarenes
  • Hydrocarbons
  • Hydrogen
  • Ideal solutions
  • Introduction to Organic Chemistry
  • Ionic equilibria
  • Matter
  • Matter Around Us
  • Matter In Our Surroundings
  • Metallurgy
  • Metals And Non-Metals
  • Mole Concept and Stoichiometry
  • Natural Resources
  • Organic Chemistry – Basic Principles
  • Periodic Classification of Elements
  • Physical and Chemical Changes
  • Physical and Chemical Properties of Water
  • Polymers
  • Preparation, Properties and Uses of Compounds
  • Principles and Processes of Isolation of Elements
  • Redox Reactions
  • Relative Molecular Mass and Mole
  • States of Matter
  • Structure Of The Atom
  • Study of Compounds
  • Study of Gas Laws
  • Study of Representative Elements
  • Surface Chemistry
  • The d-block and f-block elements
  • The Gaseous State
  • The p-Block Elements
  • The Periodic Table
  • The s-Block Elements
  • The Solid State
  • Thermodynamics

High School Biology

  • Absorption and Movement of Water in Plants
  • Adolescent Issues
  • Anatomy of Flowering Plants
  • Animal Kingdom
  • Bacteria and Fungi-Friends and Foe
  • Biodiversity and Conservation
  • Biofertilizers
  • Biological Classification
  • Biomedical Engineering
  • Biomolecules
  • Biotechnology and its Applications
  • Biotic Community
  • Body Fluids and Circulation
  • Breathing and Exchange of Gases
  • Cell – Unit of Life
  • Cell Cycle and Cell Division
  • Cell Division and Structure of Chromosomes
  • Cell Reproduction
  • Cellular Respiration
  • Chemical Coordination and Integration
  • Circulation
  • Control And Coordination
  • Crop Improvement
  • Digestion and Absorption
  • Diversity In Living Organisms
  • Ecosystem
  • Environmental Issues
  • Excretory Products and their Elimination
  • Flowering Plants
  • Genes and Chromosomes
  • Health and Diseases
  • Health and Its Significance
  • Heredity And Evolution
  • Heredity and Variation
  • How Do Organisms Reproduce?
  • Human Diseases
  • Human Eye And Colourful World
  • Human Health and Disease
  • Human Population
  • Human Reproduction
  • Hygiene
  • Improvement In Food Resources
  • Integumentary System- Skin
  • Kingdom Fungi
  • Kingdom Monera
  • Kingdom Protista
  • Life Processes
  • Locomotion and Movement
  • Microbes in Human Welfare
  • Mineral Nutrition
  • Molecular Basis of Inheritance
  • Morphology of Flowering Plants
  • Neural Control And Coordination
  • Nutrition in Human Beings
  • Organism and Population
  • Photosynthesis
  • Photosynthesis in Higher Plants
  • Plant Growth and Development
  • Plant Kingdom
  • Pollination and Fertilization
  • Pollution; Sources and its effects
  • Principles of Inheritance and Variation
  • Reproduction and Development in Angiosperms
  • Reproduction in Organisms
  • Reproductive Health
  • Respiration in Human Beings
  • Respiration in Plants
  • Respiratory System
  • Sexual Reproduction in Flowering Plants
  • Strategies for Enhancement in Food Production
  • Structural Organisation in Animals
  • Structural Organisation of the Cell
  • The Endocrine System
  • The Fundamental Unit Of Life
  • The Living World
  • The Nervous System and Sense Organs
  • Tissues
  • Transpiration
  • Transport in Plants

High School Math

  • Algebra – Arithmatic Progressions
  • Algebra – Complex Numbers and Quadratic Equations
  • Algebra – Linear Inequalities
  • Algebra – Pair of Linear Equations in Two Variables
  • Algebra – Polynomials
  • Algebra – Principle of Mathematical Induction
  • Algebra – Quadratic Equations
  • Binomial Theorem
  • Calculus – Applications of Derivatives
  • Calculus – Applications of the Integrals
  • Calculus – Continuity and Differentiability
  • Calculus – Differential Equations
  • Calculus – Integrals
  • Geometry – Area
  • Geometry – Circles
  • Geometry – Conic Sections
  • Geometry – Constructions
  • Geometry – Introduction to Euclid’s Geometry
  • Geometry – Three-dimensional Geometry
  • Geometry – Lines and Angles
  • Geometry – Quadrilaterals
  • Geometry – Straight Lines
  • Geometry – Triangles
  • Linear Programming
  • Matrices and Determinants
  • Mensuration – Areas
  • Mensuration – Surface Areas and Volumes
  • Number Systems
  • Number Systems – Real Numbers
  • Permutations and Combinations
  • Probability
  • Sequence and Series
  • Sets and Functions
  • Statistics 
  • Trignometry – Height and Distance
  • Trignometry – Identities
  • Trignometry – Introduction

Middle School Science

  • Acids, Bases And Salts
  • Air and Its Constituents
  • Basic Biology
  • Body Movements
  • Carbon and Its Compounds
  • Cell – Structure And Functions
  • Changes Around Us
  • Chemical Effects Of Electric Current
  • Chemistry in Your Life
  • Coal And Petroleum
  • Combustion And Flame
  • Components Of Food
  • Conservation Of Plants And Animals
  • Crop Production And Management
  • Electric Current And Its Effects
  • Electricity And Circuits
  • Elements and Compounds
  • Fibre To Fabric
  • Food production and management
  • Force And Pressure
  • Forests: Our Lifeline
  • Friction
  • Fun With Magnets
  • Garbage In, Garbage Out
  • Getting To Know Plants
  • Health and Hygiene
  • Heat
  • Hydrogen
  • Life Processes: Nutrition in Animals and Plants
  • Light, Shadows And Reflections
  • Materials: Metals And Non-Metals
  • Matter and Its States
  • Metals and Non-metals
  • Micro Organisms: Friend And Foe
  • Motion And Measurement Of Distances
  • Motion And Time
  • Nutrition In Animals
  • Nutrition In Plants
  • Organization in Living Things
  • Our Environment
  • Physical And Chemical Changes
  • Pollution and conservation
  • Pollution Of Air And Water
  • Reaching The Age Of Adolescence
  • Reproduction In Animals
  • Reproduction In Plants
  • Respiration In Organisms
  • Rocks and Minerals
  • Separation Of Substances
  • Simple Machines
  • Soil
  • Some Natural Phenomena
  • Sorting Materials Into Groups
  • Sound
  • Stars And The Solar System
  • Structure of Atom
  • Synthetic Fibers And Plastics
  • The Living Organisms And Their Surroundings
  • Transfer of Heat
  • Transformation of Substances
  • Transportation In Animals And Plants
  • Universe
  • Waste-water Story
  • Water: A Precious Resource
  • Weather, Climate And Adaptations Of Animals To Climate
  • Winds, Storms And Cyclones

Middle School Math

  • Addition
  • Area and Its Boundary
  • Boxes and Sketches
  • Data Handling
  • Fun With Numbers
  • Heavy and Light
  • How Many
  • Long And Short
  • Mapping
  • Measurement
  • Money
  • Multiplication and Factors
  • Multiply and Divide
  • Numbers
  • Parts and Wholes
  • Pattern Recognition
  • Patterns
  • Play With Patterns
  • Rupees And Paise
  • Shapes And Angles
  • Shapes And Designs
  • Shapes and Space
  • Similarity
  • Smart Charts
  • Squares
  • Subtraction
  • Tables And Shares
  • Tenths and Hundredths
  • Time
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