Topic 14.1 - Further aspects of covalent bonding and structure Flashcards
Metallic bonding
The electrostatic attraction between a lattice of protons and a sea of delocalised electrons
Formal charge
Number of valence electrons - 1/2 x bonding electrons - number of non-bonding electrons
The most likely structure is the one that is most correct (ie has the correct charge on the molecule and also has the - or + charge on the most or least electronegative atom)
Resonance structures
Have a bond order (typically) of .5 as the double bond has two possible positions (like in NO₂ and CH₃COO⁻) and so the structure shares the double bond over both bonding atoms. These electrons are considered delocalised.
Drawing lewis structures
When drawing lewis structure make sure to remember to include all valence electrons and remember to include square brackets showing charge on the molecule
Carbon dioxide (CO₂)
EDG: Linear
MDG: Linear
Bond angle: 180°
Boron trifluoride (BF₃)
EDG: Trigonal planar
MDG: Trigonal planar
Bond angle: 120°
Silicon dioxide (SO₂)
EDG: Trigonal planar
MDG: Bent
Bond angle: 117.5°
Ammonium (NH₄⁺)
EDG: Tetrahederal
MDG: Tetrahederal
Bond angle: 109.5°
Ammonia (NH₃)
EDG: Tetrahederal
MDG: Trigonal pyramidal
Bond angle: 107°
Water (H₂O)
EDG: Tetrahederal
MDG: Bent
Bond angle: 104.5°
Phosphorus pentafluoride (PF₅)
EDG: Trigonal bipyramidal
MDG: Trigonal bipyramidal
Bond angle: 120°, 90°
Sulfur tetrafluoride (SF₄)
EDG: Trigonal bipyramidal
MDG: See-saw
Bond angle: <120°, <90°
Chlorine trifluoride (ClF₃)
EDG: Trigonal bipyramidal
MDG: T-shape
Bond angle: <90°
Trioiodide ion (I₃⁻)
EDG: Trigonal bipyramidal
MDG: linear
Bond angle: 180°
Sulfur hexafluoride (SF₆)
EDG: Octahedral
MDG: Octahedral
Bond angle: 90°
