Summary - Unit 3.2.4 - Properties of Period 3 elements and their oxides (A-level only)

Potatoes Reaction with water
PERIOD 3 OXIDES

Nature of
Oxide Mpt (ºC) Structure & comments Reaction with acids Reaction with alkalis
What happens Equation & comments pH oxide

Dissolves i.e
“Dissolves” (i.e. Nazo 2NaOHlag
H2O  2NaOH(aq)
Na2O +H2O


1min
+




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1275 dissolves and then + 2- Na2O + 2 H 
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The Na and O ions dissolves in
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Na2O Ionic 14 + basic
(solid) reacts with water to 2-
water and then the O ions react with 2Na + H2O
form a solution) 2-
water: O + H2O  2 OH
-


MgO + H2O  Mg(OH)2(aq)
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“Slightly soluble”

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Ionic (higher melting point



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2+ 2-
(i.e. some dissolves Some Mg & O ions dissolve in water
andandisson
2+ +
2900 than Na2O as the Mg ions MgO + 2H 
e as
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MgO then reacts with (less soluble than Na2O due to higher 10 basic
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(solid) are smaller and higher 2- Mg + H2O
+ water to form a lattice enthalpy) and then the O ions
charged than Na ) 2- -
solution) react with water: O + H2O  2 OH
Ionic (not as high a melting
n

togidaat affino
point as expected due to -

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+
2040 Insoluble due to very high lattice Al2O3 + 6H  Al2O3 + 2OH + 3H2O
aporia
Al2O3 some covalent character Insoluble 3+ - amphoteric
(solid) enthalpy 2Al + 3H2O  2 Al(OH)4
due to polarising nature of

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3+
Al ions)

Insoluble dueto lattice oflinked
Insoluble due to lattice of atoms
SiO2 + 2OH 
-
2-

Gwent luble SiO3 + H2O

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1610
SiO2 Giant covalent Insoluble by strong covalent bonds that would acidic
(solid) (must be hot,
have to be broken
to be broken concentrated NaOH)

Simple molecular
simple P4O10 + 6H2O  4H3PO4
P0
Py ,0 1204 -

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580 molecular 4O10 + 12OH 
P4O10
(solid)
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(but quite a
big molecule)
reaaintly
Reacts violently
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H2O molecules attach the + P atoms,
+
d0
leading to the release of H ions from
0
faradic
3-
4PO4 + 6 H2O
acidic
the water molecules.


simple
“Dissolves” i.e
Dissolves (i.e. 5022
120 SO
SO + H O  H 12503
2 2 3
502 20H-
-75 Simple dissolves and then H2O molecules attach the + S atoms, SO2 + 2OH 

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SO2
mowar 3
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acidic



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2-


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(gas) molecular reacts with water to +
leading to the release of H ions from SO3 + H2O
form a solution) the water molecules.


simple
SO3 + H2O  H2SO4 503 20H -


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17 Simple SO3 + 2OH 
mbar d
H2O molecules attach the + S atoms,
Paainty
gfEa Total
SO3 Reacts violently 0 2- acidic
(liquid?) molecular +
leading to the release of H ions from SO4 + H2O
the water molecules.




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coaches 14-June-2016 Chemsheets A2 1073