PERIOD 3 Flashcards
Why does SO3 have a higher melting point than SO2
•bigger molecule
•stinger van der waals between molecules
SO2 reacts with water to form ions
What are the ions?
H+
HSO3-
Why does SO2 form a weakly acidic solution?
Reaction is in equilibrium
Why is SiO2 described as acidic even though it is soluble in water
Reacts with bases
Why is white phorosphorus kept under water
To prevent it from reacting with oxygen
Why is P4O10 not presented as P2O5
P4O10 is it’s molecular formula
Why can magnesium oxide be used in excess when used for a neutralisation of phosphoric acid
Insoluble
Why can an excess of NaOH be dangerous
Can turn water alkaline
Two products of Cl and H2O
HClO
HCl
Flame colour for Na and oxygen
Orange
Flame colour for Mg and oxygen
White flame
Flame colour for aluminium and oxygen
White flame
Flame colour for Si and oxygen
Orange flame
Flame colour for white phosphorus and oxygen
White flame
Reaction of Al and O2
4Al + 3O2 —> 2Al2O3
Flame colour for sulphur and oxygen
Pale blue flame
Which oxides form a white ppt
Na2O
Na2O2
Al2O3
SiO2
What is the trend in bonding across period 3
Ionic on left
Covalent on right
Why does Al2O3 have more covalent character than MgO
Al3+ is smaller
Al3+ is more polarising
Distorts electron cloud around O2-
Why do aluminium oxide and silicon dioxide not react in water
They are insoluble
What is covalent character?
The tendency of an atom to attract a pair of electrons towards itself in an ionic bond
Give two examples of how Al2O3 is amphoteric
as a base
Al2O3+6HCl –> 2AlCl3 + 3H2O
As an acid
Al2O3+ 2NaOH + 3H2O –> 2NaAl(OH)4
