Chemical Bonds

• What are compounds?


  Substances in which 2 or more elements are chemically combined
• What are the three types of strong chemical bonds?


  Ionic, covalent, and metallic
• What characterizes ionic bonds?


  Particles are oppositely charged ions
• In which compounds do ionic bonds occur?


  In compounds formed from metals combined with non-metals
• What defines covalent bonds?


  Particles are atoms which share pairs of electrons
• Where do covalent bonds typically occur?


  In most non-metallic elements and in compounds of non-metals
• What characterizes metallic bonds?


  Particles are atoms which share delocalised electrons
• In which materials do metallic bonds occur?


  In metallic elements and alloys
• What happens to electrons during ionic bonding?


  Electrons in the outer shell of the metal atom are transferred

  
• What happens to metal atoms during ionic bonding?


  They lose electrons to become positively charged ions

  
• What happens to non-metal atoms during ionic bonding?


  They gain electrons to become negatively charged ions
• What is an ion?


  An atom that has lost or gained electron(s)
• Which groups of elements produce ions in ionic bonding?


  Metals in Groups 1 and 2 and non-metals in Groups 6 and 7
• What is the result of ion formation in terms of electron configuration?


  They gain a full outer shell of electrons, resembling a noble gas
• How can electron transfer during ionic compound formation be represented?


  By a dot and cross diagram

  
• What is the structure of ionic compounds?


  A giant structure of ions
• How are ionic compounds held together?


  By strong electrostatic forces of attraction between oppositely charged ions
• How does the 3D structure of ionic compounds affect the forces acting on them?


  The forces act in every direction
• Give an example of an ionic compound.


  Sodium chloride (NaCl)

  
• What is covalent bonding?


  When atoms share one or more pairs of electrons
• What are polymers?


  Large covalently bonded molecules
• What are giant covalent structures?


  Macromolecules consisting of many atoms covalently bonded in a lattice structure
• Give examples of giant covalent structures.


  Diamond, silicon dioxide
• How can covalent substances be represented in diagrams?


  Using dot and cross, repeat units for polymers, ball and stick, and 2D/3D diagrams
• What is the arrangement of particles in metallic bonding?


  Positive ions and delocalised electrons arranged in a regular pattern
• What is the delocalised electron system in metallic bonding?


  The electrons ‘lost’ from the atoms to form positive ions
• What is the significance of delocalised electrons in metals?


  They are free to move through the structure, contributing to metallic bonding strength
• Why are metallic bonds considered strong?


  Because delocalised electrons are shared throughout the structure