Molecular compounds
rather than forming ions, the atoms of a molecule share their valence electrons in a way that forms bonds between the atoms
Properties
- gas,liquid or soils at room temperature
- variable water solubility
- low melting and boiling point
- poor electrical conductivity
- tend to be soft and relatively Flexible
- more flammable than ionic
Naming
- remove ending of second element and change to ide
- prefixes to indicate the number of a given element present in the compound
- drop prefix if only one in first element
- general more electropositive first followed by electronegative
Prefixes
Mono Di Tri Tetra Penta Hexa Hepta Octo Nona Deca
Acid Naming H+Element
- all start with hydro
- end with acid
- element ending changes to ic
H+ Polyatomic ion
+1 : per and ic
Base: ic
-1: ous
-2: hypo and ous
Bases
- most bases end with hydroxide expect for NH3 and NH4
- metal + hydroxide ion
What do we use electronegative difference to determine
If a bond is covalent or ionic
If a bond is polar or non polar
Covalent or ionic
-covalent: 1.69 or less
Ionic: 1.7 or greater
Polar and non plat
if electrons share equally or pull closer one atom
- equal EN= 0
- not equal .1 or higher bond is polar
Linear
Bonded pairs:varies
lone pairs on central atom: 0 when 3 or more atoms
Bent
Bonded pairs:2 Lone pairs on CA: 2
Ex: H20
Trigonal Planar
Bonded pairs: 3 lone pairs CA: Ex. BH3
Trigonal Pyramid
Bonded pairs : 3 Lone pairs on CA: 1
Ex. PH3
Tetrahedral
Bonded pairs : 4
Lone pairs on central atom: 0
Ex CH4
Observe Symmetry for Molecule Polarity
- when a compound is symmetrical, it is non-polar molecule
- lone pairs on central atom interfere with symmetry
- asymmetrical atom is consider polar
Using charge cancellation and dipole moment
In a compound we normally have charged atoms, so when we have an atom with a larger EN this is called slightly negative, the smaller the EN is called slightly positive
What does charge cancellation mean
No charge cancellation molecule is polar
No charge remain molecule is non polar
