C3: Structure and Bonding

• Types of bonding


  • Ionic
  • Covalent
  • Metallic
• Ionic bonding

  Electrostatic attraction between oppositely charged ions
• Elements that typically form ionic bonds

  • Metals
  • Non-metals
• Covalent bond

  Shared pair of electrons between two non-metal atoms
• Molecule

  A group of atoms bonded together by covalent bonds
• Metallic bonding

  Electrostatic attraction between positive metal ions and the sea of delocalized electrons
• Properties of ionic compounds

  • High melting and boiling points
  • Conduct electricity when molten or dissolved in water
  • Usually soluble in water
• Structure of simple molecular substances

  • Molecules held together by weak intermolecular forces
• Properties of simple molecular substances

  • Low melting and boiling points
  • Do not conduct electricity
  • Often insoluble in water
• Giant covalent structure

  Network of atoms bonded by covalent bonds
• Giant covalent structures

  • Diamond
  • Graphite
  • Silicon dioxide
• Properties of diamond

  • Very hard
  • High melting point
  • Does not conduct electricity
• Properties of graphite

  • Conducts electricity
  • Slippery
  • High melting point
• Structure of graphite

  • Layers of carbon atoms arranged in hexagons, with each carbon atom bonded to three others and one delocalized electron
• Structure of diamond

  • Each carbon atom is bonded to four other carbon atoms in a tetrahedral structure
• Properties of metals

  • Good conductors of heat and electricity
  • Malleable
  • Ductile
  • High melting and boiling points
• Alloy

  A mixture of two or more elements, where at least one is a metal
• Why are alloys stronger than pure metals?

  The different sized atoms distort the layers, making it harder for them to slide over each other
• Nanoparticle

  A particle between 1 and 100 nanometers in size
• Properties of nanoparticles

  • High surface area to volume ratio
  • Unique optical, electrical, and mechanical properties
• Uses of nanoparticles

  • Drug delivery
  • Catalysts
  • Sunscreens
  • In electronics
• Fullerenes

  Molecules of carbon atoms with hollow shapes, like tubes or spheres
• Graphene

  A single layer of carbon atoms arranged in a hexagonal lattice
• Properties of graphene

  • Very strong
  • Excellent electrical and thermal conductivity
  • Nearly transparent