period 3 Flashcards
what explains why period 3 oxides and chlorides form aq solns with pH?
- it has to dissolve
- then HYDROLYSIS
solubility of period 3 metal oxides?
decreasing solubility in water across period
solubility of periode 3 metal chlorides?
all soluble in water
period 3 metal oxides?
Na2O, MgO, Al2O3, SiO2, P4O10
period 3 metal chlorides?
NaCl, MgCl2, AlCl3, SiCl4, PCl5
pH of soluble period 3 metal oxides?
soluble ones: strongly alkaline (O2- + H2O -> 2OH-)
non-solubles: neutral
period 3 metal chloride pH and explanation?
neutral to acidic (based on the metal)
since all are soluble, the metal cations complex ions (6 H2Os) are formed.
the difference in acidity is from the polarising power of the metal cation (charge/size) which distorts and weakens the O-H bond in the H2Os, hence 6H2O -> (5H2O)(OH) releasing H+
Period 3 OXIDES reaction with Acid/Base?
metal oxide with ionic bonds = basic -> reacts with acid
metal oxide with giant ionic lattice/ significant covalent = amphoteric -> reacts with acid and base
non-metal oxides = acidic -> reacts with base
Group 2 metal thermal stability (CO3, NO3)
- cation of higher charge/size ratio
- polarises the polyatomic ion’s (CO3) electron cloud
- and weakens the C-O/N-O bond
- thus it requires less heat energy to decompose
thus: higher charge/size = lower thermal stability = lower temp
*mp/bp NOT EQUALS thermal stability
Describe and explain trend in thermal stability in grp 2 carbonates
- Decreasing charge / size ratio down grp
- decrease in polarizing power
- Electron cloud of the CO3 ion distorted to smaller extent
- Decreasing extent of weakening of bond
- More energy required to break C-O bond
Thermal stability INCREASES down grp
What does Na2O form in water
2 NaOH
What does MgO form in water
Mg(OH)2
What does Al2O3 and SiO2 form in water
no rxn
What does P4O10 form in water
4 H3PO4
What does SO3 form in water
H2SO4
