Ionic and covalent bonding

• How do you work out the formula of an ionic compound


  work out the formula for these examples $Ca^2$$^+$and $O^2$$^-$

  
• What factors influence the melting points of ionic lattices?

  The melting points are influenced by ionic charges and the size of the ions.
• How does ionic charge affect the melting point of a lattice?

  Lattices with greater ionic charges have higher melting points.
• In addition to ionic charge, what other factor affects the melting point of ionic lattices?

  The size of the ions also affects the melting point.
• What is the relationship between ionic charge, ion size, and melting point in ionic lattices?

  Higher ionic charges and smaller ion sizes lead to higher melting points.
• Many ionic compounds dissolve in polar solvents. Explain why?


  Polar molecules such as water can break down or disrupt the ionic lattice and surround each ion in solution. The solubility of an ionic compounds depends on the relative strength of electrostatic forces of attraction within the ionic lattice and the attractions between the ions and the polar molecules.

  In general the greater the ionic charge the less soluble a ionic compound is.
• electrical conductivity of ionic compounds 


  Ionic compounds cannot conduct electricity when solid because ions are in a fixed position within the solid lattice so there are no mobile charge carriers.

  When molten or aqueous ions are no longer in fixed positions as the lattice has broken down therefore ions are free to move and act as mobile charge carries.
• what is covalent bonding?


  Covalent bonding is the strong electrostatic attraction between a shared pair of electrons and the nuclei of the bonded atoms.

  • occurs between two non metal atoms
• why do simple molecules have low melting and boiling points?


  Simple molecules that make up a compound are arranged in a regular lattice held by weak intermolecular forces, since these are weak interactions not much energy is required to overcome them.
• why can simple molecules not conduct electricity?

  Simple molecules cannot conduct electricity because there are no mobile ions or electrons to carry the current.
• what is a dative covalent bond?


  When one atom donates 2 electrons to another atom or ion to form a covalent bond
• what is average bond enthalpy?


  serves as a measurement of covalent bond strength. the larger the value of the average bond enthalpy the stronger the covalent bond.