Bonding

• What type of elements does ionic bonding occur between?

  A metal and a non-metal
• What happens to electrons during ionic bonding?

  Electrons are transferred from the metal to the non-metal
• What are charged particles created during ionic bonding called?

  ions
• How do oppositely charged ions interact in ionic bonding?

  They attract through electrostatic forces
• What is an example of an ionic compound?

  Sodium chloride (NaCl)
• What is the purpose of transferring electrons in ionic bonding?

  To achieve full outer shells
• What are the characteristics of covalent bonding?

  • Forms between two non-metals
  • Electrons are shared between outer shells
  • Multiple electron pairs can be shared
  • Represented by dot and cross diagrams or straight lines
• What is a dative bond?

  A bond where both electrons in the shared pair come from a single atom
• How is a dative bond indicated in diagrams?

  With an arrow from the lone electron pair
• How is a dative bond treated after it forms?

  It is treated as a standard covalent bond
• What are the characteristics of metallic bonding?

  • Consists of a lattice of positively charged ions
  • Surrounded by a 'sea' of delocalised electrons
  • Strong electrostatic forces of attraction

  
• How does the charge of a positive ion affect metallic bonding?

  A greater charge leads to a stronger attractive force
• What effect does the size of an ion have on metallic bonding?

  Larger ions produce a weaker attraction
• What are the physical properties influenced by bonding and crystal structure?

  • Boiling point
  • Melting point
  • Solubility
  • Conductivity
• What are the four main types of crystal structure?

  1. Ionic
  2. Metallic
  3. Simple molecular
  4. Macromolecular
• What is a characteristic of ionic substances regarding melting and boiling points?

  They have high melting and boiling points
• Why can ionic substances conduct electricity when molten or in solution?

  Because the ions are free to move and carry a flow of charge
• What happens to ionic substances when layers of charges are distorted?


  They become brittle and break apart
• What is a characteristic of metallic substances regarding conductivity?

  They are good conductors of electricity
• Why are metals malleable?

  Because layers of positive ions can slide over one another
• What is the only liquid metal at room temperature?

  Mercury
• What are the characteristics of simple molecular substances?

  • Consist of covalently bonded molecules
  • Held together by weak van der Waals forces
  • Have low melting and boiling points
  • Very poor conductors
• Why do simple molecular substances have low melting and boiling points?

  Because weak van der Waals forces require little energy to overcome
• What is an example of a simple molecular substance?

  Iodine
• What are the characteristics of macromolecular substances?

  • Covalently bonded into a giant lattice structure
  • Very high melting points
  • Rigid structure
• What is an example of a macromolecular structure?

  Diamond
• How does graphite differ from diamond in terms of bonding?

  Graphite has layers of carbon atoms bonded in flat sheets

  
• Why can graphite conduct electricity?

  Because free electrons move between layers
• What determines the shape of a molecule?

  • Number of electron pairs around the central atom
  • Repulsion between electron pairs
  • Lone pairs provide additional repulsive forces
• How does the presence of lone pairs affect bond angles?

  Each lone pair reduces the bond angle by 2.5°
• What are some common molecular shapes and their characteristics?

  • Linear: 2 bonding pairs, 0 lone pairs, 180°
  • V-shaped: 2 bonding pairs, 2 lone pairs, 104.5°
  • Trigonal planar: 3 bonding pairs, 0 lone pairs, 120°
  • Triangular pyramid: 3 bonding pairs, 1 lone pair, 107°
  • Tetrahedral: 4 bonding pairs, 0 lone pairs, 109.5°
  • Trigonal bipyramid: 5 bonding pairs, 0 lone pairs, 90° and 120°
  • Octahedral: 6 bonding pairs, 0 lone pairs, 90°
• What is electronegativity?

  The power of an atom to attract negative charge towards itself within a covalent bond
• How does electronegativity change across a period and down a group?

  It increases across a period and decreases down a group
• What forms a polar bond?

  When two atoms with different electronegativities bond
• What is a permanent dipole?

  A separation of charge in a polar bond producing ∂- and ∂+ regions
• How can polar molecules align in a lattice structure?

  They can align due to their permanent dipoles
• What is an induced dipole?

  A dipole formed when electron orbitals are influenced by another charged particle

  
• What are the three main types of intermolecular forces?

  1. Van der Waals forces
  2. Permanent dipole
  3. Hydrogen bonding
• What are van der Waals forces?

  The weakest type of intermolecular force acting as an induced dipole between molecules
• How does the molecular weight (Mr) affect van der Waals forces?

  The larger the Mr, the stronger the intermolecular forces