5 - electrons and bonding

• Electron configuration


  The arrangement of electrons in an atom.
• Principal energy levels


  Energy levels or quantum shells where electrons are arranged.
• Principal quantum numbers (n)


  Used to number the energy levels or quantum shells.
• How does the principal quantum number (n) affect the energy of the shell?


  The higher the principal quantum number (the further away from the nucleus), the greater the energy of the shell.
• How many electrons can n=1 hold?

  2
• How many electrons can n=2 hold?

  8
• How many electrons can n=3 hold?

  18
• How many electrons can n=4 hold?

  32
• Subshells


  Subdivisions of principal quantum shells (s, p, d, f)
• Atomic orbitals


  Orbitals exist at specific energy levels and electrons can only be found at these specific energy levels, not in between them.
• How many electrons can be occupied in an orbital?


  2
• How many orbitals in the s-subshell?


  1
• How many electrons can occupy an s-subshell?


  2
• How many orbitals in the p-subshell?


  3
• How many electrons can occupy the p-subshell?


  6
• How many orbitals in the d-subshell?


  5
• How many electrons can occupy the d-subshell?


  10
• How many orbitals in the f-subshell?


  7
• How many electrons can occupy the f-subshell?


  14
• What is the shape of an s-orbital


  Spherical shape.
• How does the size of s orbitals change with increasing quantum shell number?


  The size of the s orbitals increases with increasing shell number.
• What is the shape of a p-orbital?


  Dumbbell shape.
• Two exceptions to the filling of orbitals rules?


  Chromium and copper.
• Principal quantum number (n)


  Number used to indicate the energy level or quantum shell
• Filling order of subshells


  s, p, d, f
• Relative atomic mass

  Weighted mean mass of one atom of an element compared to one-twelfth the mass of an atom of carbon-12.
• Relative isotopic mass

  The mass of one atom of an isotope compared with one-twelfth the mass of an atom of carbon-12.
• Simplifying electron notations

  Using noble gas/shorthand configurations.
• Ionic bonding


  The electrostatic force of attraction between oppositely charged ions formed by electron transfer. It holds together cations and anions in ionic compounds.
• Strucutre of ionic compounds


  Giant ionic lattice structures.

  
• Why do ionic compounds form giant ionic lattices?


  Each ion attracts oppositely charged ions in all directions.
• What are the properties of ionic compounds usually explained in terms of?


  The giant ionic lattice structure and ionic bonding
• What state are almost all ionic compounds at room temperature?


  Solids
• Why are almost all ionic compounds solids at room temperature?


  At room temperature, there is insufficient energy to overcome the strong electrostatic forces of attraction between the oppositely charged ions in the giant ionic lattice.
• Why do ionic compounds have high melting and boiling points?


  High temperatures are needed to provide the large quantity of energy needed to overcome strong electrostatic forces of attraction between the ions.
• How do melting points differ between ionic compounds?


  Melting points are higher for lattices containing ions with greater ionic charges. This is due to a stronger attraction between the ions.

  
  

  E.g. NaF (Na⁺ and F⁻) have a melting point of 993°C, whereas CaO (Ca²⁺ and O²⁻) have a melting point of 2614°C.
• How does the radius of atoms in an ionic compound affect melting point?


  The smaller the radius (determined by Ar) the stronger the electrostatic forces of attraction and therefore the higher the melting point.

  
  

  However, the role of charges on each ion in an ionic compound, take prioirity over the size of the atoms.
• What do many ionic compounds dissolve in?


  Polar solvents, e.g. water.
• How do polar solvents dissolve ionic compounds?


  Polar molecules, such as water, can break down or disrupt the ionic lattice and surround each ion in solution.

  
  

  - The δ+ end of the polar molecule can surround the negative anion.

  - The δ- end of the polar molecule can surround the positive cation.
• How does ionic charge affect the solubility of an ionic compound?


  The greater the ionic charge the less soluble an ionic compound is.