Metallic bonding Ammonia + HCl
= strong electrostatic attraction between metal cations and NH3 + HCl → NH4Cl (solid ∴ thick white smoke)
the sea of delocalised electrons NH3 + HCl → NH4^+ + Cl^-
Ionic bonding H+ leaves its e- w/ Cl (making it -ve) and moves to the lone
= the strong electrostatic attraction between 2 oppositely pair on the N (making NH3→NH4^+)
charged ions Aluminium chloride:
Stronger attraction between ions = stronger bonds
Al2Cl6 sublimes at 180°C (quite low)
Forces of attraction determined by:
CHARGE ∴ covalent
- Length of bond (AKA size of ion)
DENSITY Mr shows Al2Cl6 is Al2Cl6, and not AlCl3
- Charge on ions
Stronger bond = ↑ charge, small ion
- Cations are smaller than their atoms Bond energy and length:
- Anion are larger than their atoms Bond energy = the energy required to break 1 mole of a
Ionic radii: particular covalent bond in the gaseous state, kJ/mol
- Down a group, radii ↑ due to ↑ shells - ↑ bond energy = stronger bond
- Across a period, radii ↑ w/ ↑ -ve charge Bond length = the distance from the nucleus of one atom to
radii ↓ w/ ↑ +ve charge another, which forms the bond
(more -ve = bigger) - ↑ forces attraction = atoms pulled together = ↓ bond
Evidence for ionic bonding: length = ↑ strength of bond
- Electrolysis of CuCrO4 Strong bond = big bond energy & small bond length
Blue Cu^2+ (cations) to cathode Electronegativity:
Yellow CrO4^2- (anions) to anode = the ability of an atom to attract a BP of electrons in a
- Electrolysis of KMnO4 (purple) on filter paper covalent bond
Purple MnO4^- (anion) to anode ↑ across a period
Covalent bonding ↓ down a group
= the strong electrostatic attraction between a shared pair of Affected by atomic number & distance of valent e- from
electrons & the nuclei of the bonding atoms nucleus
Dative covalent bonding Polar bonds:
= one atom contributes both e-’s in a bond e.g. In a covalent bond w/ 2 different electronegativities, the BP of
e-’s will be puller towards the more EN atom (polar)
, Shapes of molecules: TRIGONAL
- Max separation, min repulsion PLANAR
- LP’s repulse more than BP’s BP = 3
LP-LP > LP-BP > BP-BP LP = 0
120°
LINEAR
BP = 2
LP = 0
180°
TETRAHEDRAL
BENT (V-
BP = 4
SHAPED)
LP = 0
BP = 2
109.5°
LP = 1
118°
TRIGONAL
TRIGONAL BIPYRAMIDAL
PYRAMIDAL BP = 5
BP = 3 LP = 0
LP = 1 120° & 90°
107°
OCTAHEDRAL
BP = 6
BENT (V- LP = 0
SHAPED) 90°
BP = 2
LP = 2
104.5°
= strong electrostatic attraction between metal cations and NH3 + HCl → NH4Cl (solid ∴ thick white smoke)
the sea of delocalised electrons NH3 + HCl → NH4^+ + Cl^-
Ionic bonding H+ leaves its e- w/ Cl (making it -ve) and moves to the lone
= the strong electrostatic attraction between 2 oppositely pair on the N (making NH3→NH4^+)
charged ions Aluminium chloride:
Stronger attraction between ions = stronger bonds
Al2Cl6 sublimes at 180°C (quite low)
Forces of attraction determined by:
CHARGE ∴ covalent
- Length of bond (AKA size of ion)
DENSITY Mr shows Al2Cl6 is Al2Cl6, and not AlCl3
- Charge on ions
Stronger bond = ↑ charge, small ion
- Cations are smaller than their atoms Bond energy and length:
- Anion are larger than their atoms Bond energy = the energy required to break 1 mole of a
Ionic radii: particular covalent bond in the gaseous state, kJ/mol
- Down a group, radii ↑ due to ↑ shells - ↑ bond energy = stronger bond
- Across a period, radii ↑ w/ ↑ -ve charge Bond length = the distance from the nucleus of one atom to
radii ↓ w/ ↑ +ve charge another, which forms the bond
(more -ve = bigger) - ↑ forces attraction = atoms pulled together = ↓ bond
Evidence for ionic bonding: length = ↑ strength of bond
- Electrolysis of CuCrO4 Strong bond = big bond energy & small bond length
Blue Cu^2+ (cations) to cathode Electronegativity:
Yellow CrO4^2- (anions) to anode = the ability of an atom to attract a BP of electrons in a
- Electrolysis of KMnO4 (purple) on filter paper covalent bond
Purple MnO4^- (anion) to anode ↑ across a period
Covalent bonding ↓ down a group
= the strong electrostatic attraction between a shared pair of Affected by atomic number & distance of valent e- from
electrons & the nuclei of the bonding atoms nucleus
Dative covalent bonding Polar bonds:
= one atom contributes both e-’s in a bond e.g. In a covalent bond w/ 2 different electronegativities, the BP of
e-’s will be puller towards the more EN atom (polar)
, Shapes of molecules: TRIGONAL
- Max separation, min repulsion PLANAR
- LP’s repulse more than BP’s BP = 3
LP-LP > LP-BP > BP-BP LP = 0
120°
LINEAR
BP = 2
LP = 0
180°
TETRAHEDRAL
BENT (V-
BP = 4
SHAPED)
LP = 0
BP = 2
109.5°
LP = 1
118°
TRIGONAL
TRIGONAL BIPYRAMIDAL
PYRAMIDAL BP = 5
BP = 3 LP = 0
LP = 1 120° & 90°
107°
OCTAHEDRAL
BP = 6
BENT (V- LP = 0
SHAPED) 90°
BP = 2
LP = 2
104.5°
