Period 3 Oxides Flashcards
Why is Na more reactive than Mg
Na needs less energy to remove 1 electron compared to Mg who needs more to remove two
How does Na react with water
- sodium reacts vigorously with cold water, forms a ball and fizzes
- gas produced is h2
- produces alkaline solution of NaOH
2Na +2H20 -> 2NaOH +H2
How does magnesium react with water
Reacts slowly
Forms weak alkaline solution of Mg(OH)2
-it’s weak because magnesium hydroxide is sparingly soluble
Mg + H20 -> Mg(OH)2 + H2
When it reacts with steam
It’s fast and it makes Mgo and H2
Which element in period three does not form an oxide
Sulphur forms sulphur dioxide
With higher temps and a catalyst can form so3
What is the equation of sodium forming an oxide and how does it react with
- Air
2Na + 1/2 o2 —> 2Na2o
Oxide: sodium oxide
Reacts very fast
White/yellow solid
yellow or orange flame
What is the equation of magnesium forming an oxide and what are the observations
- Air
Mg + 1/2 o2 —> Mgo
Oxide: MgO
Reaction: very fast
White solid
bright white light
What is the equation of aluminium forming an oxide and how does it react with
- Air
2Al + 1/2 o2 —> Al203
Oxide: Al2o3
Reaction: slow generally (fast if a powder)
What is the equation of silicon forming an oxide and how does it react with
- Air
Si + o2 —> Sio2
Reaction is slow
What is the equation of a phosphorus forming an oxide and how does it react with
- Air
P4 + 5o2 —> P4o10
Oxide: P4o10
Reaction: spontaneously combusts
What is the equation of sulphur forming an oxide and how does it react with
- Air
S + o2 —> SO2
Oxide: SO2
Reaction: steadily burns
Why does Magnesium oxide have a higher melting point that sodium oxide
Mg forms 2+ ions whereas Na forms 1+, so 2+ ions are attracted more strongly to the oxygen
Why does aluminium oxide have a lower melting point that magnesium oxide
Al 3+ ions distort election cloud of oxygen, pull electrons from oxygen towards it
So aluminium oxide has some covalent character as well as ionic interactions
This means less energy is required to break the bond
What kind of structure and bonding is there in silicon dioxide
Forms a macromolecular structure
Has many strong covalent bonds so lots of energy is retired to break then
What kind of structure and bonding do p4010 and SO2 form
Structure: simple molecular
Bonding: van der waals,
Less energy is required to break them compared to silicon dioxide
Ionic oxides
What kind of solution do Na and Mg form in water
What kind of ph is there and why
Both form alkaline solutions
Na2O creates alkaline solution of 12-14 as it dissolves readily (strong base)
MgO creates an alkaline solution of 9-10 as it dissolves sparingly in water
Simple Covalent oxides
What kind of solution does P4O10 and So2 form in water
What kind of ph is there
What is the equation for Sulphur dioxide reacting with water
Solution: acidic
pH: is 1-2
Phosphore dioxide forms phosphoric acid which can dissociate to form H+ ions
H3PO4 —> 3H+ + Po4 3-
Equation
So2 + H20 —> H2So3 (sulphuric IV acid or sulphurous acid)
To make sulphuric acid
Sulphur trioxide needs to react with water
What happens to silicon dioxide in water
Insoluble in water
Silicon dioxide is sand by the way
As there are many covalent bonds
Will react with a base to form salt so it’s classed as an acid
How does silicon dioxide react with water
It’s amphoteric, as it has both covalent and ionic characters
Insoluble in water
But will react with both acids and bases to form salts
What happens when aluminium oxide acts as an acid
1:2:3
Produces no water
2NaoH + Al2o3 +3H20 —> 2NaAl(OH)4
What happens aluminium oxide acts as an alkali
3H2SO4 + Al2O3 -> Al2(SO4)3+ 3H20
