# Chapter 5 – The periodic table

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

Introduction

When we look at so many elements present around us, it becomes necessary to arrange them in a particular order to retrieve the element’s information at any time. You must have heard about the periodic table in your science classes that is a systematic arrangement of the elements in a tabular form based on the increasing atomic number. There are rows and columns in the periodic table that holds the elements based on a particular atomic number algorithm. And surprisingly, the rows and columns groups the elements that provide certain common characteristics to those grouped elements. Let’s learn more about the periodic table in this article.

#### Dobereiner’s Triad and Newland’s law of octaves

Both of the above were some early attempts at classifying the periodic table of elements. And both worked on different algorithms.

• Dobereiner’s Triads: Dobereiner’s triads were identified and grouped based on the elements’ similar properties. This was done by the German chemist named Johan Wolfgang Dobereiner. He put three elements in a group with similar properties, and hence the name law of triads was given to it. The first and last element’s arithmetic mean was similar to the atomic mass of the second element. One example of Dobereiner’s triads is sodium, potassium and lithium. Their atomic numbers are 23, 39 and 7 g/ mol.
Limitations: However, there were some limitations to Dobereiner’s triads as the identification and discovery of new elements during that time made this system obsolete as the newly discovered elements did not fit in any of these triads. Also, not every element found at that time can be included in this triad.
• Newland’s Law of Octaves: Then came Newland’s law of octaves that organised the 62 known elements in a group of 8 with respect to their increasing atomic mass. This led to a fascinating discovery that every eighth element property was similar to the first one. It was compared to the music notes of eight octaves, and hence the name came from the law of octaves. An example of the law of octaves is lithium, sodium and potassium that share some chemical properties.
Limitations: Although the law of octaves was better than the law of triads in accommodating a large number of elements in a single periodic table, it still had its flaws. Many elements like nickel and cobalt did not fit in the table as they were allotted the same slot. Many times dissimilar property elements were placed in the same group. All these problems got rectified in the modern periodic table that takes the increasing order of atomic numbers as the organising means.

#### What is the Modern Periodic Table?

Periodic table invention dates back to the 19th century when different elements were grouped together based on certain characteristics in the late 20th century; Dmitri Mendeleev proposed a modern periodic table based on the number of electrons and protons of that element. Since it is a unique property of the elements, the atomic numbers proved to be a very useful algorithm for sorting the elements in a periodical and tabular form. Even the atomic number-based periodic table took care of the elements that have not been found yet, as space was left for that particular element in the table. Some of those elements were the f block elements.

#### Atomic Number As the Basis of Modern Periodic Table

As discussed above the Mendeleevs’s atomic mass table was re-designed based on the atomic numbers as the basis for the modern periodic table. The atomic number is the total number of electrons in the element atom.

#### Merits of the Modern Periodic Table

Although Mendeleev proposed the periodic table based on the atomic mass, it was soon modified to take the increasing atomic numbers as the deciding factor for the formation of the periodic table. Mendeleev’s periodic table was able to predict and account for the discovery of new elements in future with those particular numbers of electrons. While there are very few defects of the modern periodic table, it has been used internationally as a widely accepted periodic table.

#### Conclusion

The periodic table holds the different elements organised in a particular manner that groups the similar properties of the elements at a place. Dobereiner’s triads and the law of octaves were some of the early methods of grouping elements, and they also accompany many anomalies in them. Mendeleev proposed a periodic table based on the atomic number. It was developed and updated so that we have the atomic number as the basis for the modern periodic table. Many defects got rectified in this periodic table.

#### FAQs

1. What were the laws of triads?
The law of triads was made by a German chemist known as Dobereiner, who grouped three elements in a group according to similar properties. He found that the mean of the first and the third element’s atomic mass is very much similar to the second element atomic mass.
2. What is the law of octaves?
The Law of octaves was made by Newland and consisted of the different types of elements grouped in a periodic table, changing the row after every eighth element. He found that every eighth element property was similar to the first one, and it repeated the rule.
3. What is the basis for the modern periodic table?
The modern periodic table uses the atomic number in increasing order to group elements on the periodic table. It has mitigated all the previously made periodic table anomalies and is accepted by global standards.
4. What are some limitations of Mendeleev’s periodic table?
Mendeleev’s periodic table did not present a clear idea about the structure of the atom and the arrangement order.
5. What is the total number of elements in the periodic table?
The total number of elements in the periodic table is 118 as they have been found till now.

If you want to know more about the new elements discovered lately, then check the video tutorials from the MSVgo app that provides complete information regarding this topic.

### 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
• 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
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• Introduction to Organic Chemistry
• Ionic equilibria
• Matter
• Matter Around Us
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• Mole Concept and Stoichiometry
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• Periodic Classification of Elements
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• Preparation, Properties and Uses of Compounds
• Principles and Processes of Isolation of Elements
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• 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
• Anatomy of Flowering Plants
• Animal Kingdom
• Bacteria and Fungi-Friends and Foe
• Biodiversity and Conservation
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• Biological Classification
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• 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
• Binomial Theorem
• Calculus – Applications of Derivatives
• Calculus – Applications of the Integrals
• Calculus – Continuity and Differentiability
• Calculus – Differential Equations
• Calculus – Integrals
• Geometry – Area
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• Geometry – Introduction to Euclid’s Geometry
• Geometry – Three-dimensional Geometry
• Geometry – Lines and Angles
• Geometry – Straight Lines
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• 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
• 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
• 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

• 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