6.2 Bonding in Solids

Bonding in solids shapes their properties and behavior. From ionic crystals to metallic structures, different bond types create unique characteristics. Understanding these bonds helps predict how solids will act in various situations.

Intermolecular forces play a key role in solid formation and stability. These forces influence crystal structures and properties like melting points. Knowing how they work is crucial for grasping solid-state chemistry concepts.

Bonding in Solids

Types of Bonding

Top images from around the web for Types of Bonding

• 

  10.6 Lattice Structures in Crystalline Solids – Chemistry View original

  Is this image relevant?

• 

  Ionic bonding - Wikipedia View original

  Is this image relevant?

• 

  Mrstinechemistry - Ionic Bonding View original

  Is this image relevant?

• 

  10.6 Lattice Structures in Crystalline Solids – Chemistry View original

  Is this image relevant?

• 

  Ionic bonding - Wikipedia View original

  Is this image relevant?

1 of 3

Top images from around the web for Types of Bonding

• 

  10.6 Lattice Structures in Crystalline Solids – Chemistry View original

  Is this image relevant?

• 

  Ionic bonding - Wikipedia View original

  Is this image relevant?

• 

  Mrstinechemistry - Ionic Bonding View original

  Is this image relevant?

• 

  10.6 Lattice Structures in Crystalline Solids – Chemistry View original

  Is this image relevant?

• 

  Ionic bonding - Wikipedia View original

  Is this image relevant?

1 of 3

• Distinguish between the various types of bonding in solids, such as ionic, covalent, and metallic bonding
• Ionic bonding in solids involves the electrostatic attraction between oppositely charged ions, resulting in the formation of ionic crystals with high melting points and brittleness (sodium chloride, NaCl)
• Covalent bonding in solids involves the sharing of electrons between atoms, leading to the formation of covalent crystals with directional bonds and varying properties depending on the network structure
  • In diamond, each carbon atom forms four strong covalent bonds with its neighbors, resulting in a rigid, hard, and thermally conductive structure
  • In graphite, each carbon atom forms three covalent bonds in a planar arrangement, with weaker van der Waals forces between the layers, leading to softness and electrical conductivity
• Metallic bonding in solids involves the delocalization of valence electrons, creating a "sea" of electrons that holds the metal cations together, resulting in high electrical and thermal conductivity, ductility, and malleability (copper, Cu)

Properties and Bonding Characteristics

• Predict the properties of solids based on their bonding characteristics
• Ionic solids typically have high melting points, are brittle, and are good electrical insulators due to the strong electrostatic attractions between ions and the lack of mobile charge carriers (potassium chloride, KCl)
• Covalent solids exhibit a wide range of properties depending on their network structure, with diamond being hard, thermally conductive, and electrically insulating, while graphite is soft, electrically conductive, and thermally insulating in the direction perpendicular to the layers
• Metallic solids are typically ductile, malleable, and excellent conductors of heat and electricity due to the presence of delocalized electrons (aluminum, Al)
• Molecular solids generally have lower melting and boiling points compared to ionic, covalent, and metallic solids, and their properties are influenced by the strength of intermolecular forces (ice, H2O)

Intermolecular Forces in Solids

Role in Formation and Stability

• Explain the role of intermolecular forces in the formation and stability of solid state structures
• Intermolecular forces, such as van der Waals forces (dispersion forces, dipole-dipole interactions, and hydrogen bonding), play a crucial role in the formation and stability of molecular solids (naphthalene, C10H8)
• The strength of intermolecular forces determines the melting and boiling points of molecular solids, with stronger forces leading to higher melting and boiling points (acetic acid, CH3COOH)
• Hydrogen bonding, the strongest type of intermolecular force, is responsible for the unique properties of water and the stability of many biological structures, such as DNA and proteins

Influence on Crystal Structure

• The arrangement of molecules in a solid is influenced by the balance between intermolecular forces and the tendency to maximize packing efficiency, leading to different crystal structures
• Molecular solids can exhibit various crystal structures, such as the face-centered cubic (FCC) structure of solid noble gases (neon, Ne) or the hexagonal close-packed (HCP) structure of ice
• The presence of intermolecular forces can lead to the formation of layered structures, as seen in graphite, where the weak van der Waals forces between the layers allow for the sliding of planes

Properties of Solids

Electrical and Thermal Properties

• Ionic solids are typically good electrical insulators due to the lack of mobile charge carriers, while metallic solids are excellent conductors of electricity due to the presence of delocalized electrons
• Covalent solids can be electrical insulators (diamond) or semiconductors (silicon, Si) depending on their band structure and the presence of impurities or dopants
• Metallic solids are excellent conductors of heat due to the free movement of electrons, while ionic and molecular solids are generally poor thermal conductors (quartz, SiO2)

Mechanical Properties

• Ionic solids are typically brittle due to the strong electrostatic attractions between ions, which prevent the movement of dislocations (magnesium oxide, MgO)
• Metallic solids are ductile and malleable due to the presence of delocalized electrons, which allow for the movement of atoms without breaking bonds (gold, Au)
• Covalent solids can be hard and rigid (diamond) or soft and layered (graphite) depending on their network structure and the strength of the covalent bonds

Electronic Structure of Solids

Band Theory

• Analyze the electronic structure of solids using band theory and the concept of energy bands
• Band theory describes the electronic structure of solids by considering the energy levels of electrons as they are affected by the periodic potential of the crystal lattice
• The overlap of atomic orbitals in a solid leads to the formation of energy bands, which are continuous ranges of allowed energy levels for electrons
• The valence band is the highest occupied energy band at 0 K, while the conduction band is the lowest unoccupied energy band

Band Gap and Electrical Properties

• The energy gap between the valence and conduction bands, known as the band gap, determines the electrical properties of a solid
• Insulators have a large band gap, preventing electrons from easily moving from the valence band to the conduction band (diamond, band gap: 5.5 eV)
• Semiconductors have a smaller band gap, allowing some electrons to be excited into the conduction band at higher temperatures or with an external energy source (silicon, band gap: 1.1 eV)
• Conductors have overlapping valence and conduction bands, or a partially filled conduction band, enabling electrons to move freely and conduct electricity (copper)