Bonding

Bonding

1. Ionic Compounds

   • Chemical bonds
     • There are 3 types of strong chemical bonds
       • Ionic
       • Metallic
       • Covalent
   • Ionic Bonding
     • Ions are formed when atoms gain or lose electrons, giving them an overall charge
     • Ions have a complete outer shell of electrons
     • Ionic bonding involves a transfer of electrons from metal atoms to non-metal atoms
     • The metal atoms lose electrons to become positively charged ions
     • non-metal atoms gain electrons to become negatively charged ions
     • the ionic bond is a strong electrostatic force of attraction between the positive metal ion and the negative non-metal ion
   • Properties of ionic compounds
     • ionic compounds are giant structures of ions
     • They are held together by strong forces of attraction that act in all directions between oppositely charged ions
     • ionic compounds
       • high melting and boiling points
       • don`t conduct electricity when solid because the ions can`t move
       • conduct electricity when molten because the particles are free to move and carry their charge

2. Covalent Bonding

   • A covalent bond is a shared pair of electrons between atoms
   • where covalent bonds occur
     • non-metallic elements
     • compounds of non-metals
   • covalent bonds in molecules can be shown using dot and cross diagrams
   • covalent bonds are very strong
   • Small Molecules
     • small molecules contain a relatively small number of non-metal atoms joined by covalent bonds
     • the molecules have no overall charge, so they can`t conduct electricity
     • substance that consist of small molecules usually have low melting and boiling points
       • this is because of weak intermolecular forces between the molecules
     • these intermolecular forces are very weak compared to the strength of the covalent bondsin the molecules themselves
     • the larger the molecules are the stronger the intermolecular forces between the molecules become
     • larger molecules have higher melting and boiling points
   • giant covalent structures
     • all the atoms in giant covalent structures are linked by strong covalent bonds
     • these bonds must be broken for the substance to melt or boil
     • means that giant covalent structures have very high melting and boiling points
     • diamond is a form of carbon
       • giant, rigid covalent structure (lattice)
       • each carbon atom forms four strong covalent bonds with other carbon atoms
       • all the strong covalent bonds mean that it is a very hard substance with a very high melting point
       • no charged particles, so it doesn`t conduct electricity