Unit 2 Flashcards
(19 cards)
Bond Classification (Electronegativity)
EN = higher EN - lower EN
• non polar covalent: EN <0.5
• polar covalent: EN = 0.5 - 1.7
• ionic: EN > 1.7
Partial Charges
δ− : element with more electrons in a bond (to the right)
δ+ : element with less electrons in a bond (to the left)
*Hydrogen is an exception. It has a duplet so it is usually gains a negative partial charge
Properties of Ionic Compounds
- crystalline solid
- soluble in water
- good electrolytes
- high melting/ boiling points
Properties of Molecular Compounds
- solid, liquid, gas
- insoluble in water
- poor electrolytes
- low melting/ boiling points
Shapes of Molecules
AX2: Linear, polar AX2E: Bent, non-polar AX3: Planar triangular, non-polar AX3E: Triangular pyramidal, non-polar AX4 (E): Tetrahedral (polar if all surrounding atoms are the same)
Ion-Dipole
Not a true intermolecular force. Attraction between ion (+,-) and partial charge in a polar molecule.
Dipole-Dipole
Attraction between opposite partial charges in neighbouring polar molecules. Effective only when molecules are close together. For molecules of almost equal size and mass, increasing polarity increases attractive force.
Hydrogen Bonding
Very strong dipole-dipole attraction between δ+ in H and δ− in polar molecules containing F,O,N
London Dispersion Forces
Very weak attraction between atoms in neighbouring non polar molecules based on temporary dipoles formed from asymmetrical electron distributed.
Metal and Non-Metal (Ionic)
Name of metal (Roman numerals for multivalent cation)
+
stem of nonmetal + ide
Two Nonmetals (Covalent/Molecular)
Prefix + name of 1st nonmetal
+
Prefix + stem of 2nd nonmetal + ide
H + Metal
Metal name
+
hydride
H + Carbons
Special names
eg. Methane = CH4
H + Group 15 Nonmetals
Common names
eg. NH3 = ammonia
eg. PH3 = phosphine
H + Group 16/17 Nonmetals (Dry)
Hydrogen
+
Stem of nonmetal + ide
H + Group 16/17 Nonmetals (Aqueous)
Hydro + stem of 2nd nonmetal + ic
+
acid
Containing Polyatomic Ions (Ionic)
Metal or NH4+ Cation
Name of metal or ammonium
+
Polyatomic ion
Containing Polyatomic Ions (Ionic)
H+ Cation (Dry)
Hydrogen
+
Polyatomic ion
Containing Polyatomic Ions (Ionic)
H+ Cation (Aqueous)
Stem of polyatomic ion + ous (ite)/ ic (ate)
+
acid
