3.2.4 Period 3 Elements Flashcards
State how and under what conditions, sodium and magnesium react with water
Sodium- reacts with cold water vigorously
Floats on water, fizzes, melts
2Na + 2H2O —> 2NaOH + H2
Magnesium- reacts with steam/slowly with water
Steam: Mg + H2O —> MgO + H2
Water: Mg + 2H2O —> Mg(OH)2 + H2 sparingly soluble
State how the group 3 elements react with oxygen?
Na: burns with yellow-orange flame to produce white powder
Mg,Al,Si: burns with white flame to produce white powder
P4: burns with very bright white flame to produce white powder
S8: burns with blue flame + gives off choking gas
Cl2: No reaction
4Na + O2 —> 2Na2O / 2Na + O2 —> Na2O2
2Mg + O2 —> 2MgO
4Al + 3O2 —> 2Al2O3
Si + O2 —> SiO2
P4 + 5O2 —> P4O10 / P4 + 3O2 —> P4O6
S + O2 —> SO2
Structure, bonding, melting point of Na2O, MgO, Al2O3
All ionic-lattice structure, high boiling points (solid)
Bp order: MgO, Al2O3, Na2O
MgO + Al2O3 > Na2O as Mg2+ ions are smaller + more charged
MgO > Al2O3 as Al2O3 has some covalent character due to polarising nature of Al3+
Structure, bonding, melting point of SiO2
Giant covalent (solid)
High boiling point
Structure, bonding, melting point of P4O10
Simple molecular
Relatively high boiling point (solid)
Large molecule-strong IMF
Structure, bonding, melting point of SO2 + SO3
Simple molecular
Low boiling points
Bp- SO3 is larger molecule than SO2 so higher- more IMF
SO2- gas
SO3- liquid
Group 2 oxide reaction with water trend + how the structures explain their reactions
General increase in solubility
Na2O- dissolves + reacts with water to form solution
Na2O + H2O —> 2NaOH(aq)
MgO- slightly soluble- some dissolves + reacts with water to form solution
MgO + H2O —> Mg(OH)2(aq)
Al2O3- insoluble - high lattice enthalpy
SiO2- insoluble - high lattice enthalpy due to covalent bonds
P4O10- violent reaction
P4O10 + 6H2O —> 4H3PO4
SO2- dissolves + reacts with water to form solution
SO2 + H2O —> H2SO3
SO3- violent reaction
SO3 + H2O —> H2SO4
Na+/Mg2+ and O2- ions dissolve in water
O2- + H2O —> 2OH- (ionic)
P/S are partially positive so attach to H2O molecules to produce H+ ions from water molecules (simple molecular)
Describe how the period 3 oxides react with acids
Metals react with acids (Na2O,MgO,Al2O3) to produce metal cations and water
Na2O + 2H+ —> 2Na+ + H2O
MgO + 2H+ —> Mg2+ + H2O
Al2O3 + 6H+ —> 2Al3+ + 6H2O
Basic oxides
Describe how the period 3 oxides react with bases
Al2O3,SiO2,P4O10,SO2,SO3 react with bases to form negative ions
Al2O3 + 2OH- + 3H2O —> 2Al(OH)4-
SiO2 + 2OH- —> SiO32- +H2O (hot, conc NaOH)
P4O10 + 12OH- —> 4PO43- + 6H2O
SO2 + 2OH- —> SO32- + H2O
SO3 + 2OH- —>SO42- + H2O
Which metal oxide is amphoteric + define
Al2O3
Acts as acid or base
pH of
NaOH
Mg(OH)2
4H3PO4
H2SO3
H2SO4
SO2
SO3
14
10
1-2
3
0
2-3
0-1
Explain why sodium oxide forms an alkaline solution when it reacts with water
Na2O contains O^2- ions
Ions react with water to form OH^-
Silicone melting point
Very high
Very strong covalent structure
Lots of energy required to break strong covalent bonds
Melting point of phosphorus to chlorine
Simple covalent held together by weak van der Waals
Less energy required to overcome
Why does Argon have lower melting point than chlorine
Noble gas
Individual atoms with full outer shell electrons
Stable with weak Van der Waals
Less energy required to overcome
Appearance and physical properties of sodium
Metallic, shiny, conducts electricity
Appearance and physical properties of magnesium
Metallic, shiny, conducts electricity
Appearance and physical properties of aluminum
Metallic, shiny, conducts electricity
Reaction of Al with cold water
No reaction
Why is aluminium considered unreactive even though the metal itself is reactive
Covered by Al2O3 from oxidation
If Al2O3 scratched off, Al reacts rapidly with air to form new coat
Appearance and physical properties of silicon
Semimetal, semiconductor of electricity
Appearance and physical properties of phosphorus
Non-metal, low melting + boiling point, doesn’t conduct electricity
Red has crystal structure
White as P4
Reaction of phosphorus in limited oxygen
Incomplete combustion
4P + 3O2 —> P4O6
Appearance and physical properties of sulphur
Non-metal, low melting + boiling point, doesn’t conduct electricity
Which period 3 oxides are basic
Na2O and MgO, Al2O3
Is aluminium oxide soluble
Not in water
Reaction of aluminium oxide with NaOH
Al2O3 + 2NaOH + 3H2O —> 2NaAl(OH)4
Sodium aluminate
Is silicon dioxide soluble in water
No
In what conditions will silicon dioxide act as an acid
Reacts as weak acid with strong base
Reaction of silicon dioxide with hot conc NaOH
SiO2 + 2NaOH —> H2O + Na2SiO3
Sodium silicate
How is silicon dioxide used in the production of Fe
SiO2 + CaO —> CaSiO3
Calcium silicate
Reaction of P4O10 with NaOH
3NaOH + H3PO4 —> Na3PO4 + 3H2O
Reaction of SO2/SO3 with water
SO2 + H2O —> H2SO3
SO3 + H2O —> H2SO4
Reaction of SO2 with NaOH (2 reactions)
SO2 + NaOH —> NaHSO3
NaHSO3 + NaOH —> Na2SO3 + H2O
Structure, bonding and shape in PO4^3-/SO4^2-
Electrons delocalise to give tetrahedral structure
Each P-O/S-O bond same length
109.5°
Structure, bonding and shape of SO3^2-
Trigonal pyramid shape
Each S-O bond the same
S has one lone pair of electrons
107° bond angle
Uses of MgO
Additive to cattle feed
Uses of SO2
Reactant in contact process making H2SO4
