Chemical Bonding

Chemical Bonding

Table of Contents

Introduction

Definition: Chemical bonding refers to the attraction and attachment between two or more atoms to form molecules or compounds.

Importance of chemical bonding

  • Understanding chemical bonding is crucial in chemistry, biology, material science, and pharmacology.
  • It helps in predicting the properties and behavior of substances.
  • Essential for drug design, material synthesis, and environmental studies.

Types of chemical bonds

  • Ionic bonds: Formed by the transfer of electrons from one atom to another, resulting in charged ions.
  • Covalent bonds: Result from the sharing of electrons between atoms, creating molecules.
  • Metallic bonds: Occur in metals, where electrons are delocalized and move freely among metal atoms.

Ionic Bonding

Explanation of ionic bonding

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  • Ionic bonding is a type of chemical bond that forms between two ions of opposite charges.
  • It involves the transfer of valence electrons from one atom to another.
  • The result is the formation of positive and negative ions.

Formation of ions and their charges

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  • Ions are formed when atoms gain or lose valence electrons.
  • Cations are positively charged ions formed by losing electrons.
  • Anions are negatively charged ions formed by gaining electrons.

Electrostatic attraction between oppositely charged ions

Why is ionic bonding stronger than hydrogen bonding? | Socratic

  • The oppositely charged ions are attracted to each other due to electrostatic forces.
  • This attraction is strong and results in the formation of an ionic bond.
  • The bond is stable due to the balance of positive and negative charges.

Examples of compounds formed through ionic bonding

  • Sodium Chloride (NaCl): Sodium (Na) loses an electron to become a cation, and chlorine (Cl) gains this electron to become an anion.
  • Calcium Chloride (CaCl2): Calcium (Ca) forms a 2+ cation, and chlorine (Cl) forms anions, resulting in a 2:1 ratio.
  • Potassium Bromide (KBr): Potassium (K) forms a cation, and bromine (Br) forms an anion, leading to the ionic bond between them.

Covalent Bonding

Explanation of covalent bonding

Covalent Bond - Definition, Examples, Types, Properties, & FAQs

  • Covalent bonding is a type of chemical bond where atoms share electrons to achieve stability.
  • It occurs between non-metal atoms which have similar electronegativities.
  • The shared electrons move around the nuclei of both atoms, binding them together.

Sharing of electrons between atoms

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  • In covalent bonding, two atoms share one or more pairs of electrons.
  • This sharing allows both atoms to attain a full outer electron shell, similar to the noble gases.

Types of covalent bonds: single, double, and triple bonds

Types of Chemical Bonds

  • Single Bond: One pair of electrons is shared between two atoms. Represented by a single line in chemical structures.
  • Double Bond: Two pairs of electrons are shared between two atoms. Represented by a double line in chemical structures.
  • Triple Bond: Three pairs of electrons are shared between two atoms. Represented by a triple line in chemical structures.

Examples of compounds formed through covalent bonding

  • Water (H2O): Formed by the covalent bonding between hydrogen and oxygen atoms.
  • Methane (CH4): Consists of carbon and hydrogen atoms bonded covalently.
  • Oxygen gas (O2): Comprises two oxygen atoms bonded by a double covalent bond.
  • Nitrogen gas (N2): Formed by a triple covalent bond between two nitrogen atoms.

Key Points

  • Covalent bonding involves the sharing of electrons between non-metal atoms.
  • It results in the formation of molecules.
  • Different types of covalent bonds (single, double, and triple) are distinguished by the number of electron pairs shared between atoms.

Metallic Bonding

Explanation of metallic bonding

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  • Atoms: Metallic bonding involves the attraction between metal atoms.
  • Electrons: Outer valence electrons are loosely held and can move freely.
  • Positive Nuclei: Metallic atoms release positive ions.

Delocalized electrons and their role in metallic bonding

Lesson Explainer: Metallic Bonding | Nagwa

  • Delocalized Electrons: Valence electrons are not tied to a specific atom.
  • Mobility: These electrons can move freely throughout the metal structure.
  • Attraction: They are attracted to the positive metal ions.

Properties of metals resulting from metallic bonding:

  • Malleability: Metals can be hammered into thin sheets.
  • Ductility: They can be drawn into wires.
  • Conductivity: Excellent electrical and thermal conductivity due to free electrons.
  • Luster: Shiny appearance due to reflective electrons.

Examples of metals with metallic bonding:

  • Gold: Used in jewelry due to its malleability and luster.
  • Copper: Important for electrical wiring because of its conductivity.
  • Iron: Used in construction due to its strength and ductility.

Intermolecular Forces

Definition of intermolecular forces

  • Intermolecular forces are weak attractions between molecules.
  • These forces are responsible for holding molecules together in liquids and solids.

Types of intermolecular forces:

  • London Dispersion Forces

Define London dispersion forces. Draw a picture showing how London forces  arise. Are London forces relatively strong or relatively weak? Explain.  Although London forces exist among all molecules, for what type of 

    • Temporary and weakest intermolecular forces.
    • Occur in all molecules due to momentary fluctuations in electron distribution.
  • Dipole-Dipole Interactions

20 Enigmatic Facts About Ion-Dipole Interactions - Facts.net 

    • Result from the attraction between permanent dipoles in polar molecules.
    • Stronger than London dispersion forces.
  • Hydrogen Bonding

Diagram of hydrogen bonding. | Download Scientific Diagram 

    • A special type of dipole-dipole interaction.
    • Involves a hydrogen atom bonded to a highly electronegative atom (like O, N, or F) in one molecule and another electronegative atom in another molecule.
    • Strongest among the intermolecular forces.

Influence of intermolecular forces on physical properties of substances

  • Boiling point and melting point:
    • Substances with stronger intermolecular forces tend to have higher boiling and melting points.
  • State of Matter:
    • Gases typically have weak intermolecular forces.
    • Liquids have moderate intermolecular forces.
    • Solids have strong intermolecular forces.
  • Viscosity:
    • Higher intermolecular forces lead to higher viscosity (resistance to flow).
  • Surface Tension:
    • Higher intermolecular forces result in higher surface tension (resistance to increase in surface area).

Examples of substances with different types of intermolecular forces

  • London Dispersion Forces:
    • Noble gases like helium (He), neon (Ne), and argon (Ar).
  • Dipole-Dipole Interactions:
    • HCl (hydrogen chloride), CH₂Cl₂ (dichloromethane).
  • Hydrogen Bonding:
    • Water (H₂O), ammonia (NH₃), ethanol (C₂H₅OH).

Molecular Geometry

Properties of Molecular Geometry

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  • Shape dictates function: The arrangement of atoms in a molecule influences how it interacts with other molecules.
  • Reactivity: Molecules with different shapes exhibit varying degrees of reactivity.
  • Polarity: Geometry affects the distribution of charge within a molecule, leading to differences in polarity.
  • Physical properties: Molecular geometry influences properties like melting and boiling points.

VSEPR Theory

VSEPR theory - Labster

  • VSEPR stands for: Valence Shell Electron Pair Repulsion theory.
  • Basic idea: Electron pairs (both bonding and non-bonding) around a central atom repel each other.
  • Predicting shape: VSEPR helps determine the most stable arrangement of atoms around a central atom to minimize electron pair repulsion.
  • Steps:
    1. Count the total number of electron pairs around the central atom.
    2. Determine the number of bonding pairs and non-bonding pairs.
    3. Predict the molecular shape based on these counts.

Examples of Different Molecular Geometries

  • Linear:
    • Geometry: Two atoms around a central atom with a 180° bond angle.
    • Example:
  • Trigonal Planar:
    • Geometry: Three atoms in the same plane around a central atom with a 120° bond angle.
    • Example:
  • Tetrahedral:
    • Geometry: Four atoms around a central atom with a 109.5° bond angle.
    • Example:
  • Trigonal Bipyramidal:
    • Geometry: Five atoms around a central atom in a bi-pyramid shape with bond angles of 90° and 120°.
    • Example:
  • Octahedral:
    • Geometry: Six atoms around a central atom with a 90° bond angle.
    • Example:

Bond Polarity

Definition of bond polarity

3.4: Bond Polarity - Chemistry LibreTexts

  1. Bond polarity refers to the distribution of electrons between two atoms in a chemical bond.
  2. It determines whether a bond is polar (unequal sharing of electrons) or nonpolar (equal sharing of electrons).

Explanation of electronegativity

Electronegativity | Mulliken's Scale and Pauling's scale

  1. Electronegativity is the ability of an atom to attract electrons in a chemical bond.
  2. Atoms with higher electronegativity values tend to attract electrons more strongly.
  3. The difference in electronegativity between two bonded atoms determines the degree of bond polarity.
    • Large electronegativity difference: polar bond
    • Small or no electronegativity difference: nonpolar bond

Polar covalent bonds and nonpolar covalent bonds

Polar covalent bonds:

  • Formed between atoms with different electronegativities.
  • Electrons are unequally shared, leading to partial charges on atoms.
  • Examples: H2O (water), HCl (hydrochloric acid).

Covalent Bond - Definition, Examples, Types, Properties, & FAQs

Nonpolar covalent bonds:

  • Formed between atoms with similar electronegativities.
  • Electrons are equally shared, no partial charges present.
  • Examples: O2 (oxygen gas), N2 (nitrogen gas).

Examples of compounds with polar and nonpolar bonds

Compounds with polar bonds:

  • Water (H2O): Oxygen (O) is more electronegative than hydrogen (H), leading to a polar bond.
  • Hydrochloric acid (HCl): Chlorine (Cl) is more electronegative than hydrogen (H), resulting in a polar bond.

Compounds with nonpolar bonds:

  • Oxygen gas (O2): Both oxygen atoms have similar electronegativities, leading to a nonpolar bond.
  • Nitrogen gas (N2): Both nitrogen atoms share electrons equally, resulting in a nonpolar bond.

Conclusion

  • Chemical bonding is the process by which atoms combine to form molecules and compounds.
  • Atoms bond to achieve a more stable and lower energy state.
  • Covalent bonds occur when atoms share electrons, leading to molecules.
  • Ionic bonds form when atoms transfer electrons, resulting in ions.
  • Metallic bonds involve a sea of electrons shared between metal atoms, giving metals their unique properties.
  • Intermolecular forces play a role in holding molecules together in liquids and solids.
  • Understanding chemical bonding is crucial in predicting and explaining the properties and behaviors of substances.
  • The type of bond influences the physical and chemical properties of a substance.

In essence, the study of chemical bonding is fundamental to understanding the structure, properties, and interactions of matter at the atomic level.

FAQ’s

Imagine tiny building blocks (atoms) holding hands. A chemical bond is the “handhold” that keeps these atoms stuck together, forming new substances called molecules or compounds.

  • Ionic Bonding: This is like a tug-of-war between a metal and a non-metal atom. The metal lets go of electrons (becomes positive), and the non-metal happily grabs them (becomes negative). Opposite charges attract, so they bond! (Think of salt: Na⁺ and Cl⁻)
  • Covalent Bonding: Here, atoms share electrons, like two kids holding onto the same toy. They take turns “playing” with the electrons, creating a strong bond. (Think of water: H₂O)
  • Metallic Bonding: In metals, it’s a party! Electrons aren’t attached to any one atom, but instead move freely throughout the metal. This “sea of electrons” creates a strong attraction between positive metal ions, holding the metal together. (Think of a wire)
  • London Dispersion Forces (weaker bond): Even though some atoms are shy about sharing electrons, they can still be attracted to each other slightly. These temporary attractions are like weak handshakes between atoms. (Think of the reason why boiling water turns to gas)

If you’re in Class 11 chemistry, you’ll be diving deeper into the world of chemical bonds. You’ll learn the details of each bond type, how they affect properties of substances, and how to predict what kind of bond will form between different atoms.

There are two main categories for chemical bonds:

  • Ionic Bonds: These involve a complete transfer of electrons between atoms, creating charged ions that attract each other.
  • Covalent Bonds: Here, atoms share electrons, achieving a stable outer shell configuration.

Beyond the two main types, there are additional bonding forces:

  • Metallic Bonding: The unique bonding in metals with a “sea of electrons.”
  • London Dispersion Forces: Weaker attractions between otherwise non-bonding atoms.
  • Hydrogen Bonding: A special type of covalent bond with hydrogen that creates strong attractions in some molecules (like water).

MCQs of Chemical Bonding


1. Which type of bond involves the sharing of electrons between atoms?

  • A. Ionic bond
  • B. Metallic bond
  • C. Covalent bond
  • D. Hydrogen bond

Answer: C. Covalent bond


2. In an ionic bond, electrons are:

  • A. Shared
  • B. Transferred
  • C. Lost
  • D. Gained

Answer: B. Transferred


3. What type of bond is formed between a metal and a non-metal?

  • A. Covalent bond
  • B. Metallic bond
  • C. Ionic bond
  • D. Van der Waals bond

Answer: C. Ionic bond


4. The bond between two oxygen atoms in an oxygen molecule (O2) is:

  • A. Covalent
  • B. Ionic
  • C. Metallic
  • D. Hydrogen

Answer: A. Covalent


5. Which bond is characterized by a sea of electrons?

  • A. Covalent bond
  • B. Metallic bond
  • C. Ionic bond
  • D. Polar bond

Answer: B. Metallic bond


6. Intermolecular forces are responsible for holding molecules together in which state of matter?

  • A. Gas
  • B. Liquid
  • C. Solid
  • D. Both B and C

Answer: D. Both B and C


7. What type of bond is formed between hydrogen and oxygen atoms in a water molecule?

  • A. Ionic bond
  • B. Covalent bond
  • C. Metallic bond
  • D. Van der Waals bond

Answer: B. Covalent bond


8. Which bond is the weakest among the following?

  • A. Covalent bond
  • B. Ionic bond
  • C. Hydrogen bond
  • D. Metallic bond

Answer: C. Hydrogen bond


9. What causes the formation of a hydrogen bond?

  • A. Sharing of electrons
  • B. Transfer of protons
  • C. Attraction between a hydrogen atom and an electronegative atom
  • D. Sharing of protons

Answer: C. Attraction between a hydrogen atom and an electronegative atom


10. Which type of bond is found in a diamond?

  • A. Ionic bond
  • B. Covalent bond
  • C. Metallic bond
  • D. Hydrogen bond

Answer: B. Covalent bond


11. Which bond is formed due to the electrostatic attraction between positively charged ions and negatively charged ions?

  • A. Covalent bond
  • B. Metallic bond
  • C. Ionic bond
  • D. Polar bond

Answer: C. Ionic bond


12. The bond between two atoms of the same element is always:

  • A. Ionic
  • B. Metallic
  • C. Covalent
  • D. Hydrogen

Answer: C. Covalent


13. What is the main factor that determines the strength of an ionic bond?

  • A. Number of protons
  • B. Size of the ions
  • C. Number of neutrons
  • D. Distance between the ions

Answer: D. Distance between the ions


14. In which type of bond are electrons not shared equally?

  • A. Nonpolar covalent bond
  • B. Polar covalent bond
  • C. Ionic bond
  • D. Metallic bond

Answer: B. Polar covalent bond


15. What is the charge on an ion that loses two electrons?

  • A. +1
  • B. +2
  • C. -1
  • D. -2

Answer: B. +2


16. The bond between sodium (Na) and chlorine (Cl) in NaCl is:

  • A. Covalent
  • B. Ionic
  • C. Metallic
  • D. Hydrogen

Answer: B. Ionic


17. Which bond type is characterized by the sharing of both electrons in the bond?

  • A. Single covalent bond
  • B. Double covalent bond
  • C. Triple covalent bond
  • D. Ionic bond

Answer: A. Single covalent bond


18. Which bond is responsible for the unique properties of water?

  • A. Covalent bond
  • B. Metallic bond
  • C. Ionic bond
  • D. Hydrogen bond

Answer: D. Hydrogen bond


19. What type of bond is formed between carbon atoms in diamond?

  • A. Ionic bond
  • B. Covalent bond
  • C. Metallic bond
  • D. Van der Waals bond

Answer: B. Covalent bond


20. Which bond is primarily responsible for the structure of proteins and DNA?

  • A. Covalent bond
  • B. Metallic bond
  • C. Ionic bond
  • D. Hydrogen bond

Answer: A. Covalent bond

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