ATOMIC BONDINGS IN SOLID
Bonding Forces and Energies
Metallic Bonding
Introduction to Atomic Bonding
• Properties of solids are determined by atomic bonds.
• Focus on bonding forces, energies, and metallic bonding.
• Atoms bond to achieve a more stable, lower energy state.
Valence Electrons and Bonding
• Valence electrons (outermost shell) are key to bonding.
• Electrons are transferred or shared to form bonds.
• Atoms tend to achieve stable electron configurations (like noble
gases).
Types of Primary Chemical Bonds
• Ionic Bonding: Electron transfer creates ions, which attract.
• Covalent Bonding: Electron sharing holds atoms together.
• Metallic Bonding: Delocalized electrons shared among a "sea" of
atoms.
Bonding Forces
• Attractive Forces: Pull atoms together (electrostatic).
• Repulsive Forces: Oppose attraction, significant at close range.
• Nucleus-nucleus repulsion.
• Electron cloud repulsion (Pauli Exclusion Principle).
Bonding Energy
• Bonding energy: Energy needed to separate bonded atoms to infinite
distance.
• Measure of bond strength.
• Potential energy curve illustrates bonding energy.
Potential Energy Curve
• X-axis: Interatomic distance (r).
• Y-axis: Potential energy (E).
• Minimum energy at equilibrium distance (r0).
• Bonding energy (E0) at minimum point.
• Net Energy (EN) = Attractive Energy (EA) + Repulsive Energy (ER)
Metallic Bonding: The Electron Sea Model
• Valence electrons delocalized throughout metal lattice.
• Positive ion cores in a "sea" of mobile electrons.
Characteristics of Metallic Bonding
• alized Electrons
• Positive Ion Cores
• Electrostatic Attraction
• Non-directional Bonding
Properties of Metals Explained by Metallic
Bonding
• High Electrical Conductivity: Free electron movement.
• High Thermal Conductivity: Efficient energy transfer.
• Malleability and Ductility: Non-directional bonding allows atoms to
slide.
• Metallic Luster: Electron interaction with light.
• Variable Strength
Factors Affecting Metallic Bond Strength
• Number of Valence Electrons: More electrons, stronger bonds.
• Atomic Radius: Smaller radius, stronger bonds.
• Nuclear Charge: Greater charge, stronger bonds
• Crystal Structure: Close-packed structures = stronger bonds
• Electronegativity: Influences electron distribution in alloys
Significance of Understanding Metallic Bonding
• Alloy Design: Tailoring properties.
• Material Selection: Choosing the right metal.
• Predicting Material Behavior.
• Advanced Materials: High-entropy alloys, metallic glasses.
Conclusion
• Atomic bonding, especially metallic bonding, is key to understanding
solid material properties.
• Metallic bonding with delocalized electrons explains unique metallic
properties.
• Understanding bonding is essential for utilizing metals in technology.