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How many covalent bonds can an atom form? Valency in Organic Chemistry

The atoms that form covalent bonds are the nonmetals (p-block elements), and they must have an electronegativity difference lower than 1.7. These values also help to classify the covalent bond into two kinds, polar and nonpolar.

What is the maximum number of covalent bonds?

The number of covalent bonds an atom can form depends on its valency. An atom’s valency is the number of electrons that is in excess or less to reach a stable noble gas configuration. The stable noble gas configuration has 8 electrons in the outermost shell. The atom will try to lose, gain, or share electrons to reach the coveted number 8. Therefore, valency is indicative of the combining capacity of the atom.
 
The common atoms of the p-block elements that engage in covalent bond formation have valencies 4, 3, 2, and 1. The Carbon group has valency 4, the Nitrogen group has valency 3, the Oxygen group has valency 2, and the Halogen group has valency 1.

What is valency valence in chemistry

The outermost shell of carbon has 4 electrons. It has 4 electrons less from a stable octet configuration of Neon. Carbon combines with other atoms so that it receives four electrons, forming four new bonds. The Nitrogen is less by 3, Oxygen by 2, and Halogen by one. These atoms will then combine in a manner so that they form a 3, 2, and 1 bond. Therefore, valence also provides information on the number of bonds an atom can form. 
 
The atom not necessarily has to find another partner to fulfill its valence; it can even form a bond with itself.
 
For example, Oxygen has a valency of two and can form two bonds. Oxygen can form these two bonds by combining with two Hydrogens to form a molecule of water (H-O-H), or it can form two bonds with itself to obtain an Oxygen (O=O) molecule. The Oxygen atom's valence of 2 can also be met by bonding with Carbon to form carbonyl (R2-C=O) or Carbon dioxide (O=C=O).
 
Nitrogen has a valency of 3 and can combine in various combinations like N2, NH3, CN, (CH3)3N, etc.
 
Halogen, with its valency of one, can form one covalent bond -for example, HF, CH3-Cl, Cl-Cl, etc.
 
Therefore, based on their valence, Carbon is tetravalent, Nitrogen is trivalent, Oxygen is divalent, and Halogen is monovalent.
 

number of covalent bonds


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About the chapter - Bonding in Atoms

Octet Rule determines Ionic and Covalent Bonds. The chapter offers in-depth coverage of the rule and demonstrates how to assess bonding in atoms by analyzing the nature, formation, requirement, types, number, and other bond-related properties. The chapter ends with metallic bonding, its nature, significance, and application, with a complete overview of the difference between various bond types.

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What is Organic Chemistry?

  • Introduction
  • Elements of a Chemical Reaction
  • Components of a Chemical Reaction

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Atom

  • Size of an atom- The world belongs to the tiniest!
  • Power of Protons
  • Mass Number
  • Average Atomic Mass
  • Molecule and Molecular Mass
  • The Electrons- An Atom’s Reactive Component
  • Atomic Orbitals- s, p, d, f
  • Filing of Atomic Orbitals and Writing Electronic Configuration
  • Valence and Core Electrons- How to Determine

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Bonding In Atoms

  • Octet Rule- Introduction and Bonding
  • Limitations of Octet Rule
  • Ionic Bond- Introduction and Formation
  • Formation of Ionic Compound
  • Requirements for Ionic Bonding
  • Appearance and Nature of Ionic Compounds
  • Physical Properties of Ionic Solids- Conductance, Solubility, Melting Point, and Boiling Point
  • Covalent Bond - How it Forms
  • Covalent Bond - Why it Forms?
  • Covalent Bond- Bond Pair (Single, Double, Triple) and Lone Pair
  • Number of Covalent Bonds- Valency
  • Types of Covalent Bonds- Polar and Nonpolar
  • Metallic Bonds- Introduction and Nature
  • Significance of Metallic Bonding
  • Impact of Metallic Bonding on the Physical Properties
  • Applications of Metallic Bonding
  • Difference Between Metallic and Ionic Bond

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Covalent Bond

  • Theories on Covalent Bond Formation
  • Valence Bond Theory- Introduction and Covalent Bond Formation
  • Valence Bond Theory- Types of Orbital Overlap Forming Covalent Bonds
  • Applications, Limitations, and Extensions of Valence Bond Theory
  • Hybridization- Introduction and Types
  • sp3 Hybridization of Carbon, Nitrogen, and Oxygen
  • sp2 Hybridization of Carbon, Carbocation, Nitrogen, and Oxygen
  • sp Hybridization of Carbon and Nitrogen
  • Shortcut to Determine Hybridization
  • VSEPR Theory- Introduction
  • Difference between Electron Pair Geometry and Molecular Structure
  • Finding Electron Pair Geometry and Related Shape
  • Predicting Electron-Pair Geometry and Molecular Structure Guideline
  • Predicting Electron pair geometry and Molecular structure - Examples
  • Finding Electron-Pair Geometry and Shape in Multicentre Molecules
  • Drawbacks of VSEPR Theory
  • Covalent bond Characteristics- Bond length
  • Factors affecting Bond Length
  • How does Electron delocalization (Resonance) affect the Bond length?
  • Covalent bond Characteristics- Bond Angle
  • Factors affecting Bond Angle
  • Covalent bond Characteristics- Bond Order
  • How Bond Order Corresponds to the Bond Strength and Bond Length
  • Solved Examples of Bond Order Calculations
  • Covalent Bond Rotation
  • Covalent Bond Breakage
  • Covalent Bond Properties -Physical State, Melting and Boiling Points, Electrical Conductivity, Solubility, Isomerism, Non-ionic Reactions Rate, Crystal structure

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Electronic Displacement in a Covalent Bond

  • Electronegativity- Introduction
  • Factors Affecting Electronegativity- Atomic number, Atomic size, Shielding effect
  • Factors Affecting Electronegativity-s-orbitals, Oxidation state, Group electronegativity
  • Application of Electronegativity in Organic Chemistry
  • Physical Properties Affected by Electronegativity
  • Inductive effect- Introduction, Types, Classification, and Representation
  • Factors Affecting Inductive Effect- Electronegativity
  • Factors Affecting Inductive Effect- Bonding Order and Charge
  • Factors Affecting Inductive Effect- Bonding Position 
  • Application of Inductive Effect- Acidity Enhancement and Stabilization of the counter ion due to -I effect 
  • Application of Inductive Effect-Basicity enhancement and stabilization of the counter ion due to +I effect
  • Application of Inductive Effect-Stability of the Transition States
  • Application of Inductive Effect-Elevated Physical Properties of Polar Compounds
  • Is the Inductive Effect the same as Electronegativity?
  • Resonance- Introduction and Electron Delocalization 
  • Partial Double Bond Character and Resonance Hybrid
  • Resonance Energy
  • Significance of Planarity and Conjugation in Resonance
  • p-orbital Electron Delocalization in Resonance
  • Sigma Electron Delocalization (Hyperconjugation)
  • Significance of Hyperconjugation
  • Resonance Effect and Types
  • Structure Drawing Rules of Resonance (Includes Summary)
  • Application of Resonance
  • Introduction to Covalent Bond Polarity and Dipole Moment
  • Molecular Dipole Moment
  • Lone Pair in Molecular Dipole Moment
  • Applications of Dipole Moment
  • Formal Charges- Introduction and Basics
  • How to Calculate Formal Charges (With Solved Examples)
  • Difference between Formal charges and Oxidation State

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Common Types of Reactions

  • Classification of common reactions based on mechanisms
  • Addition Reactions
  • Elimination Reactions (E1, E2, E1cb)
  • Substitutions (SN1, SN2, SNAr, Electrophilic, Nucleophilic)
  • Decomposition
  • Rearrangement
  • Oxidation-Reduction

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Drawing Organic Structures

  • Introduction
  • Kekulé
  • Condensed
  • Skeletal or Bond line
  • Polygon formula
  • Lewis Structures- What are Lewis structures and How to Draw
  • Rules to Draw Lewis structures- With Solved Examples
  • Lewis structures- Solved Examples, Neutral molecules, Anions, and Cations
  • Limitation of Lewis structures
  • 3D structure representation- Dash and Wedge line
  • Molecular models for organic structure representation- Stick model, Ball-stick, and Space-filling
  • Molecular Formula

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Functional Groups in Organic Chemistry

  • What are functional groups? 
  • Chemical and Physical Properties affected by the Functional Groups
  • Identifying Functional Groups by name and structure
  • Functional Group Categorization- Exclusively Carbon-containing Functional Groups
  • Functional Group Categorization- Functional Groups with Carbon-Heteroatom Single Bond
  • Functional Group Categorization- Functional Groups with Carbon-Heteroatom Multiple Bonds
  • Rules for IUPAC nomenclature of Polyfunctional Compounds
  • Examples of polyfunctional compounds named according to the priority order
  • Examples of reactions wherein the functional group undergoes transformations

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Structural Isomerism

  • Introduction
  • Chain Isomerism
  • Position Isomerism
  • Functional Isomerism
  • Tautomerism
  • Metamerism
  • Ring-Chain Isomerism

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Intermolecular Forces

  • Ion-Dipole Interactions-Introduction and Occurrence
  • Factors Affecting the Ion-Dipole Strength
  • Importance of Ion-Dipole Interactions
  • Ion-Induced Dipole- Introduction, Strength and Occurrence
  • Factors Affecting the Strength of Ion-Induced Dipole Interactions
  • Ion-Induce Dipole Interactions in Polar Molecules
  • Vander Waals Forces -Introduction
  • Examples of Vander Waals' forces
  • Vander Waals Debye (Polar-Nonpolar) Interactions
  • Factors affecting the Strength of Debye Forces
  • Vander Waals Keesom Force- Introduction, Occurrence and Strength
  • Vander Waals London Forces- Introduction, Occurrence, And Importance
  • Factors Affecting the Strength of London Dispersion Forces- Atomic size and Shape
  • Introduction, Occurrence and Donor, Acceptors of Hydrogen Bond
  • Hydrogen bond Strength, Significance and Types
  • Factors Affecting Hydrogen Bond Strength
  • Impact of Hydrogen bonding on Physical Properties- Melting and boiling point, Solubility, and State
  • Calculation of the Number of Hydrogen Bonds and Hydrogen bond Detection

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Physical Properties

  • Physical Properties- Introduction, Role of Intermolecular Forces
  • Physical State Change-Melting Point
  • Role of Symmetry, Role of Carbon numbers, Role of Geometry
  • Physical State Change-Boiling Point
  • Intermolecular Forces and their Effect on the Boiling Point, Role of Molecular Weight (Size), Molecular Shape, Polarity
  • Boiling Point of Special Compounds- Amino acids, Carbohydrates, Fluoro compounds
  • Solubility in Water
  • Density

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Fundamentals of Organic Reactions

  • Types of Arrows Used in Chemistry
  • Curved Arrows in Organic Chemistry- with Examples
  • Electrophiles- Introduction, Identification and Reaction
  • Formation and Classification of Electrophiles- Neutral and Charged 
  • Difference between Electrophiles and Lewis Acids
  • Nucleophile- Identification and Role in a Reaction
  • Types of Nucleophiles- Lone Pair
  • Types of Nucleophiles- Pie Bond
  • Types of Nucleophiles- Sigma Bond
  • Periodic Trend and Order in Nucleophilicity
  • Introduction to Reactions Involving Nucleophiles
  • Nucleophile Reactions- Aliphatic Displacement type - SN1, SN2
  • Nucleophile Reactions- Acyl Displacement type
  • Nucleophile reactions- Aromatic Displacement type- Electrophilic, Nucleophilic
  • Addition Reactions- Electrophilic, Nucleophilic, and Acyl
  • Ambident Nucleophiles- Introduction and Formation 
  • Ambident Nucleophile - Nature of the Substrate
  • Ambident Nucleophile- Influence of the Positive Counter Ions
  • Ambident Nucleophile- Effect of Solvent 
  • Lone Pair - Introduction and Formation
  • Physical Properties Affected by the Lone Pair- Shape and Bond Angle
  • Physical Properties Affected by the Lone Pair- Hydrogen Bonding
  • Physical Properties Affected by the Lone Pair- Polarity and Dipole Moment
  • Chemical property affected by the Lone pair- Nucleophilicity
  • Leaving Group- Introduction and Nature
  • Good and Bad Leaving Group
  • Factors Determining Stability of the Leaving Groups- Electronegativity, Size, Resonance Stability
  • Using pKa as a Measure of Leaving Group Ability
  • Leaving Groups in Displacement Reactions
  • Leaving Groups in Elimination Reactions

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Reactive Intermediates

  • Carbocation- Introduction, Nature, and Types
  • Formation of Carbocation
  • Stability of Carbocations- Inductive, Resonance, and Hyperconjugation
  • Other Structural Features Increasing Carbocation Stability
  • Structural Feature Decreasing Carbocation Stability
  • Fate of the Carbocation
  • General Carbocation Formation Reactions
  • Carbanion- Introduction, Nature, and Types
  • Formation of Carbanions
  • Carbanion Stabilization
  • Ease of Formation of Carbanion -Acidic proton
  • Fate of the Carbanion
  • Free Radical- Introduction and Types of Carbon-Centred Radicals
  • Structure of Carbon-Centred Free Radical
  • Formation of Radicals
  • Stability of the Carbon-Centred Radicals
  • Other Structural Feature Increasing Free Radical Stability
  • Comparing Free Radical Stability using Dissociation energies (D-H) 
  • Fate of Free Radicals
  • Common Reactions Involving Carbon-Free Radicals

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