Electrons, bonding and structure

• What is an orbital?

  A region that hold up to two electrons with opposite spins
• How many electrons can each orbital hold?

  2 electrons
• How do orbitals fill?

  Fill singly before pairing
• When is the d orbital exception?

  d4 and d9 - S orbital promotes an electron to make d5 or d10
• How can electronic configuration be written?

  Fully or from previous noble gas e.g. Li = 1s2 2s1 or [He] 2s1
• What is ionic bonding?


  The electrostatic attraction between oppositely charged ions
• What is a giant ionic lattice?

  A Giant Ionic lattice is where every positive ion is surrounded by negative ion
• How does ionic bonding affect properties?

  Increased bp/mp, soluble in polar solvents, only conduct in molten/ aqueous states where free ions are able to move and pass on charge
• What is covalent bonding?

  The electrostatic attraction between a shared pair of electrons and the nuclei of the bonded atoms
• What is average bond enthalpy?

  A measure of how strong a covalent bond is
• Order of electron repulsion

  LP/LP>LP/BP>BP/BP
• How much does a lone pair repel?

  2.5 degrees more than bond pairs
• Linear

  2 atoms bonded to the central atom, 180 degrees
• Non-linear


  2 atoms bond to a central atom, 2 lone pairs, 104.5 degrees
• Trigonal planar

  3 bonds, 0 lone pairs, 120 degrees
• Tetrahedral


  4 bonds, 0 lone pairs, 109.5 degrees
• Octahedral

  6 bonds, 0 lone pairs, 90 degrees
• Pyramidal


  3 bonds, 1 lone pair, 107 degrees
• What structures do ionic compounds tend to form?

  Giant ionic lattices
• What is the nitrate ion?

  NO3
• What is the carbonate ion?

  CO3 2-
• What is the sulphate ion?

  SO4 2-
• What is the ammonium ion?

  NH4+
• What is a covalent bond?

  A shared pair of electrons
• What is a dative covalent bond?

  A covalent bond in which a shared pair of electrons is supplied by one of the bonding atoms only
• What is metallic bonding?

  The attraction between positive metallic ions and delocalised electrons
• Properties of ionic compounds?

  High MP/BP from strong electrostatic forces

  - Conducts in liquid/ aqueous forms but not solid
• What is electronegativity?

  The ability of an atom to attract the bonding electrons in a covalent bond
• What are the most electronegative elements?

  NOF - Nitrogen, oxygen, fluorine
• What is a polar bond?

  A covalent bond in which electrons are shared unequally
• What is a dipole?

  The difference in polarity in a polar bond
• How is polarity represented?


  Delta positive/ negative symbols
• What is induced dipole-dipole interactions?

  When the charge density of one molecule repels the electrons in another molecule, causing the delta positive end to be attracted to the original molecule
• Why is ice less dense than water?


  Because ice forms a rigid, open lattice due to hydrogen bonding
• Why does ice have a high mp/bp?

  because hydrogen bonding between molecules is strong, causing high latent heat capacity, requiring a large amount of energy to break bonds
• Why are some covalent molecules covalent lattices?

  They can form repeating geometric structures
• Physical properties of simple covalent

  Low mp/by, not electrically conductive in solid state, soluble depending on polarity of solvent