Z = 11 Sodium Na in Group 1 Alkali Metals
The structure of the element: element : o
Giant lattice metallic structure of immobile positive metal ions surrounded by a 'sea' of freely moving mobile electrons (so -called delocalised electrons).
Physical properties: properties: o
2
2-
+
2-
4Na(s) + O2(g) ==> 2Na2O(s) sodium oxide (Na )2O . +
and Na(s) + O2(g) ==> Na2O2(s) sodium peroxide, (Na )2[O2]
2-
Reaction of oxide with water : o
Na2O is a very basic oxide, readily dissolving/reacting to form an alkaline solution of sodium hydroxide of pH 14.
Na2O(s) + H2O(l) ==> 2NaOH(aq)
Reaction of oxide with acids: o
Behaves as a basic oxide dissolving to form the chloride, sulphate and nitrate salt in the relevant dilute acid.
o
Na2O(s) + 2HCl (aq) ==> 2NaCl(aq) + H2O(l)
o
Na2O(s) + H2SO4(aq) ==> Na2SO4(aq) + H2O(l)
o
Na2O(s) + 2HNO 3(aq) ==> 2NaNO 3(aq) + H2O(l)
o
In all cases the ionic equation is: Na2O(s) + 2H
+
+
(aq)
==> 2Na
(aq)
+ H2O(l)
Reaction of oxide with strong bases/alkalis: o
1
+
6
Burns when heated in air to form the ionic white solid oxides, sodium oxide, Na 2O or (Na )2O .
2
Gp1 Alkali Metal; Metal ; e.c. 2,8,1 or 1s or 1s 2s 2p 3s ; (+1 (+1 only) e.g. in NaCl, Na 2O etc.
Reaction of element with oxygen: oxygen : o
o
Group, electron configuration (and oxidation states): states) : o
o
A Soft silvery solid, less dense than water; mpt 98 C; bpt 883 C; good conductor of heat/electricity.
None, None, sodium oxides are ONLY basic.
Reaction of element with chlorine: chlorine : o
+
-
Burns when heated in chlorine to form white powder/colourless crystals of ionic sodium chloride, NaCl or Na Cl .
2Na(s) + Cl2(g) ==> 2NaCl (s)
Reaction of chloride with water : o
The salt readily dissolves forming a neutral solution of sodium and chloride ions (pH 7). + (aq)
-
NaCl(s) + aq ==> Na
+ Cl (aq)
The chloride ion is such a weak base it shows no chemical interaction with water and the sodium ion shows virtually no acidic character, so sodium chloride solution is neutral ~pH 7.
Reaction of element with water : o
The metal reacts quite quickly forming hydrogen gas and alkaline sodium hydroxide, pH 14.
2Na(s) + 2H2O(l) ==> 2NaOH(aq) + H2(g) Z = 12 Magnesium Mg in Group 2 Alkaline Earth Metals
The structure of the element: o
Giant lattice metallic structure of immobile positive metal ions surrounded by a 'sea' of freely moving mobile electrons (so -called delocalised electrons).
Physical properties: o
2
6
2
2+
2-
Burns brightly when heated in air to form a white powder of ionic magnesium oxide Mg O when heated strongly in air.
2Mg(s) + O2(g) ==> 2MgO(s)
Reaction of oxide with water : o
It is slightly soluble in water, and is a basic oxide forming an alkaline solution of magnesium hydroxide
o
Mg (OH )2, of about pH12.
2+
2
Gp2 Alkaline Earth Metal; e.c. 2,8,2 or 1s 2s 2p 3s ; (+2 only) e.g. MgCl 2, MgO.
Reaction of element with oxygen: o
o
Group, electron configuration (and oxidation states): o
o
A moderately hard silvery-white solid; mpt 649 C; bpt 1090 C; good conductor of heat/electricity.
-
MgO(s) + H2O(l) ==> Mg(OH)2(aq)
Reaction of oxide with acids: o
Behaves as a basic oxide dissolving to form the chloride, sulphate and nitrate salt in the relevant dilute acid.
o
MgO(s) + 2HCl(aq) ==> MgCl2(aq) + H2O(l)
o
MgO(s) + H2SO4(aq) ==> MgSO4(aq) + H2O(l)
o
MgO(s) + 2HNO3(aq) ==> Mg(NO3)2(aq) + H2O(l)
o
In all cases the ionic equation is: MgO(s) + 2H
2+ (aq)
+ H2O(l)
None, sodium oxide is ONLY basic. 2+
-
Forms colourless solid ionic magnesium chloride, Mg (Cl )2, when heated in chlorine.
Mg(s) + Cl2(g) ==> MgCl2(s)
Reaction of chloride with water : o
The salt dissolves in water forming a nearly neutral solution of about pH6.
o
o
MgCl2(s) + aq ==> Mg
2+ (aq)
-
+ 2Cl (aq)
or more correctly ...
2+ (aq)
MgCl2(s) + 6H2O(l) ==> [Mg(H 2O)6]
-
+ 2Cl (aq)
The solution is slightly acidic, because the hexa-aqa magnesium ion can donate a proton to a water molecule forming the oxonium ion, more simply H
==> Mg
Reaction of element with chlorine: o
(aq)
Reaction of oxide with strong bases/alkalis: o
+
+
(aq).
2+ (aq)
[Mg(H2O)6]
+ H2O(l)
+
[Mg(H2O)5OH]
(aq)
+ H3O
+ (aq)
Reaction of element with water : o
Very slow reaction with cold water to form hydrogen (bubbles form slowly on the surface) and alkaline magnesium hydroxide.
o
Mg(s) + 2H2O(l) ==> Mg(OH) 2(aq) + H2(g)
Ignited magnesium will continue to burn in steam to form the white powder of magnesium oxide and hydrogen gas and you get the same reaction if steam is passed over heated magnesium.
Mg(s) + H2O(g) ==> MgO (s) + H2(g)
Other comments: Z = 13 Aluminium Al in Group 3/13
The structure of the element: o
Giant lattice metallic structure of immobile positive metal ions surrounded by a 'sea' of freely moving mobile electrons (so -called delocalised electrons).
Physical properties: o
o
Group, electron configuration (and oxidation states): o
o
Moderately hard silvery-white high melting solid; mpt 661 C; bpt 2467 C; good conductor heat/electricity. 2
2
6
2
1
Gp3; e.c. 2,8,3 or 1s 2s 2p 3s 3p ; (+3 only) e.g. Al2O3 and AlCl3.
Reaction of element with oxygen: o
3+
4Al(s) + 3O2(g) ==> 2Al2O3(s)
The above reaction occurs very rapidly on a freshly cut aluminium surface, but the microscopic oxide layer inhibits any further reaction, giving aluminium a 'lower reactivity' than expected, and its excellent anti-corrosion properties.
Reaction of oxide with water : o
2-
Reacts when heated strongly in air to form a white powder of aluminium oxide which has a giant ionic structure, (Al )2(O )3.
Insoluble, no reaction but it is an amphoteric oxide and forms salts with both acids and alkali (see below).
Reaction of oxide with acids: o
It behaves as a basic oxide dissolving to form the chloride, sulphate and nitrate salt in the relevant dilute acid.
o
Al2O3(s) + 6HCl (aq) ==> 2AlCl3(aq) + 3H2O(l)
o
Al2O3(s) + 3H2SO4(aq) ==> Al2(SO4)3(aq) + 3H2O(l)
o
Al2O3(s) + 6HNO 3(aq) ==> 2Al(NO 3)3(aq) + 3H2O(l)
o
ionic equation: Al2O3(s) + 6H
+
3+
(aq)
==> 2Al
(aq)
+ 3H2O(l)
Reaction of oxide with strong bases/alkalis: o
The oxide also behaves as an acidic oxide by dissolving in strong soluble bases to form aluminate(III) salts.
o
e.g. Al2O3(s) + 2NaOH(aq) + 3H2O(l) ==> 2Na[Al(OH)4](aq)
o
forming sodium aluminate(III) with sodium hydroxide.
o
ionic equation: Al2O3(s) + 2OH (aq) + 3H2O(l) ==> 2[Al(OH) 4] (aq)
o
Therefore aluminium oxide is an amphoteric oxide, because of this dual acid-base behaviour.
-
Reaction of element with chlorine:
-
o o
*
Burns when heated strongly in chlorine gas to form the white solid aluminium chloride on heating in chlorine gas.
2Al(s) + 3Cl2(g) ==> 2AlCl 3(s)
*
It is often a faint yellow in colour, due to traces of iron forming iron(III) chloride.
Aluminium chloride is a curious substance in its behaviour. The solid, AlCl3, consists of an ionic lattice of Al -
3+
ions, each
o
surrounded by six Cl ions, BUT on heating, at about 180 C, the thermal kinetic energy of vibration of the ions in the lattice is sufficient to cause it break down and sublimationtakes place (s ==> g). In doing so the co-ordination number of the aluminium changes from six to four to form the readily vapourised covalent dimer molecule, Al2Cl6, shown above.
Reaction of chloride with water : o
With a little water it rapidly, and exothermically hydrolyses to form aluminium hydroxide and nasty fumes of hydrogen chloride gas.
o
AlCl3(s) + 3H2O(l) ==> Al(OH) 3(s) + 3HCl(g)
However, if a large excess of water is rapidly added, a weakly acidic solution of aluminium chloride is formed, with the minimum of nasty fumes!
o
3+
-
AlCl3(s) + aq ==> Al
or more correctly: AlCl3(s) + 6H2O(l) ==> [Al(H2O)6]
(aq)
+ 3Cl (aq) 3+ (aq)
-
+ 3Cl (aq)
The solution is slightly acidic, because the hexa-aqa aluminium ion can donate a proton to a water molecule forming the oxonium ion.
[Al(H2O)6]
3+ (aq)
+ H2O(l)
2+ (aq)
[Al(H2O)5OH]
+
+ H3O
(aq)
Reaction of element with water : o
None due to protective oxide layer.
Reactions of the hexa-aqua aluminium ion: o
It gives a gelatinous white precipitate with sodium hydroxide or ammonia solution which displays amphoteric behaviour by dissolving in excess strong alkali ( NaOH(aq), NOT NH 3(aq)) and acids. 3+ (aq)
-
Al
+ 3OH (aq) ==> Al(OH) 3(s)
or [Al(H2O)6]
3+ (aq)
-
+ 3OH (aq) ==> [Al(OH)3(H2O)3] + 3H2O(l)
The hydroxide readily dissolves in acids to form salts:
Al(OH) 3(s) + 3H
+
3+
(aq)
==> Al
(aq)
+ 3H2O(l) +
3+ (aq)
or more elaborately: [Al(OH)3(H2O)3] + 3H3O
Thus showing amphoteric behaviour, since the hydroxide ppt. also dissolves in excess strong
(aq)
[Al(H2O)6]
+ 3H2O(l)
alkali (below).
3+ [Al(H2O)6] (aq)
o
-
3(aq)
+ 6OH (aq) ==> [Al(OH)6]
or [Al(OH) 3(H2O)3](s) +
3OH (aq)
or more simply Al(OH) 3(s) +
+ 6H2O(l) (from original aqueous ion) 3(aq)
==> [Al(OH)6]
3OH (aq)
+ 3H2O(l) (from hydroxide ppt.) 3(aq)
==> [Al(OH)6]
(from hydroxide ppt.)
With aqueous sodium carbonate solution, the hydroxide ppt. is formed, and, because of its acidic nature, bubbles of carbon dioxide gas are evolved. 3+ (aq)
2(aq)
+ CO3
2+ (aq)
2[Al(H 2O)6]
2[Al(H2O)5(OH)]
+ H2O(l) + CO2(g)
this process of proton donation continues until the gelatinous ppt. [Al(OH)3(H2O)3](s) is formed, but will not dissolve in excess of the weak base/alkali.
See Appendix 1 in Transition Metal Chemistry pages for more examples and equations etc.
No Cr 2(CO3)3 is formed because of the acid-base reaction above, due to the acidity of the chromium(III) ion. Note the 3+
3+
similarly highly charged and small ions Cr and Fe
behave in the same way.
Z = 14 Silicon Si in Group 4/14
The structure of the element:
o
Non-metal existing as a giant covalent lattice, Sin, where n is an extremely large number, held together by tetrahedrally arranged Si-Si bonds.
Physical properties: o
o
o
Hard high melting solid; mpt 1410 C; bpt 2355 C; poor conductor of heat/electricity, but with other elements added, conducts better, hence use in microchips.
Group, electron configuration (and oxidation states): o
2
None and insoluble.
None, only acidic in nature.
Reaction of oxide with bases/alkalis: o
It is a weakly acidic oxide dissolving very slowly in hot concentrated sodium hydroxide solution to form sodium silicate.
o
SiO2(s) + 2NaOH(aq) ==> Na2SiO3(aq) + H2O(l)
o
or simplified ionic equation: SiO2(s) + 2OH (aq) ==> SiO3
-
Si(s) + 2Cl2(g) ==> SiCl4(l)
Reaction of chloride with water : o
Hydrolyses to form gelatinous hydrated silicon oxide and hydrochloric acid.
SiCl4(l) + 2H2O(l) ==> SiO2(s) + 4HCl(aq)
Reaction of element with water : o
+ H2O(l)
On heating in chlorine forms the covalent liquid silicon tetrachloride.
2(aq)
Reaction of element with chlorine: o
Si(s) + O2(g) ==> SiO2(g)
Reaction of oxide with acids: o
2
Reaction of oxide with water : o
2
Reacts when strongly heated in air to form silicon dioxide (silica, silicon(IV) oxide).
6
Reaction of element with oxygen: o
2
Gp4; e.c. 2,8,4 or 1s 2s 2p 3s 3p ; (+4 only) e.g. SiO2 and SiCl4 etc.
None
Other comments:
o
-
Links to other pages on site:
Z = 15 Phosphorus P in Group 5/15
The structure of the element: o
Physical properties: o
o
2
2
6
2
3
o
Gp5; e.c. 2,8,5 or 1s 2s 2p 3s 3p ; Variety of oxidation states from -3 to +5 e.g.
o
PH3 (-3), P4O6 (+3), P4O10, PCl5 and H3PO4 (+5).
Reaction of element with oxygen: With limited air/oxygen, on heating the phosphorus, the covalent white solid phosphorus(III) oxide is formed.
o
P4(s) + 3O2(g) ==> P4O6(s)
With excess air/oxygen, on heating the phosphorus, the co valent white solid phosphorus(V) oxide is formed.
P4(s) + 5O2(g) ==> P4O10(s)
Reaction of the oxides with water : Both oxides dissolve in water to form acidic solutions. o
Phosphoric(III) oxide forms phosphoric(III) acid.
o
P4O6(s) + 6H2O(l) ==> 4H3PO3(aq)
Phosphoric(III) oxide forms phosphoric(V) acid.
o
Colourless gas; mpt 44 C; bpt 280 C; poor conductor of heat/electricity.
Group, electron configuration (and oxidation states):
o
Two solid allotropes (red and white) consisting of P4 molecules, also a polymer form.
P4O10(s) + 6H2O(l) ==> 4H 3PO4(aq)
Reaction of element with chlorine: o
With limited chlorine, on heating the phosphorus, the covalent liquid phosphorus(III) chloride is formed.
P4(s) + 3Cl2(g) ==> 4PCl 3(l)
o
*
With excess chlorine, on heating the phosphorus, the ionic solid phosphorus(III) chloride is formed.
P4(s) + 5Cl2(g) ==> 4PCl 5(s) *
PCl5 is a bit unusual for an 'expected covalent' liquid chloride.
+
-
It is an ionic solid with the structure [PCl4] [PCl6]
Hence its melting point is much greater than the liquid phosphorus(III) chloride, where the molecules are only held together by the inter-molecular forces.
Reaction of oxide with acids: o
None, only acidic in nature.
Reaction of oxide with bases/alkalis: o
Both oxides dissolve in alkalis to form a whole series of phosphate(III) and phosphate(V) salts.
o
with excess strong bases like sodium hydroxide, the simplified equations are:
P4O6(s) + 12NaOH(aq) ==> 4Na3PO3(aq) + 6H2O(l) sodium phosphate(III) formed from phosphorus(III) oxide
o
-
ionic equation: P4O6(s) + 12OH (aq) ==> 4PO3
3(aq)
+ 6H2O(l)
P4O10(s) + 12NaOH (aq) ==> 4Na3PO4(aq) + 6H2O(l) sodium phosphate(V) formed from phosphorus(V) oxide
However, gaseous phosphorus(V) chloride consists of PCl5 covalent molecules.
-
3(aq)
ionic equation: P4O10(s) + 12OH (aq) ==> 4PO4
+ 6H2O(l)
If the empirical formulae P 2O3 and P2O5 are used, just halve all the balancing numbers.
Other than using excess sodium hydroxide, other salts can be formed.
e.g. P4O10(s) + 4NaOH(aq) + 2H2O(l) ==> 4NaH2PO4(aq) sodium dihydrogen phosphate(V)
or P4O10(s) + 8NaOH(aq) ==> 4Na2HPO4(aq) + 2H2O(l) disodium hydrogen phosphate(V)
-
Reaction of the chlorides with water : o
Phosphorus(III) chloride hydrolyses rapidly and exothermically to form phosphoric(III) acid.
o
PCl3(l) + 3H2O(l) ==> H3PO3(aq) + 3HCl(aq)
Phosphorus(V) chloride initially hydrolyses to form phosphorus oxychloride and hydrochloric acid.
PCl5(s) + H2O(l) ==> POCl 3(aq) + 2HCl(aq)
Then on boiling the aqueous solution, phosphoric(V) acid is formed and more hydrochloric acid.
POCl3(aq) + 3H2O(l) ==> H 3PO4(aq) + 3HCl(aq)
overall: PCl5(s) + 4H2O(l) ==> H3PO4(aq) + 5HCl(aq)
Reaction of element with water : None.
o
Z = 16 Sulphur S in Group 6/16
The structure of the element: o
Three solid allotropes. Two are crystalline lattices based on S8 molecules (rhombic and monoclinic sulfur). A 3rd form is
an unstable dark brown-black polymeric form called plastic sulphur, formed when boiling sulphur is poured onto cold water, great fun, but of little use!
Physical properties: o
o
Group, electron configuration (and oxidation states): 2
2
6
2
4
o
Gp6; e.c. 2,6 or 1s 2s 2p 3s 3p ; ranges from (-2 to +6) e.g.
o
Na2S (-2), S2Cl2 (+1), SO2 (+4) and H2SO4, SF6, SO3 (all +6).
Reaction of element with oxygen: o
Burns in air with a pale blue flame to f orm sulphur dioxide (sulphur(IV) oxide), with a little sulphur trioxide.
o
S(s) + O2(g) ==> SO2(g)
Sulphur trioxide (sulphur(VI) oxide) has to be made by the industrial Contact Process.
o
Colourless gas; mpt 117 C; bpt 445 C; poor conductor of heat/electricity.
o
2SO2(g) + O2(g) == V2O5 catalyst, 450 C ==> 2SO3(g)
Reaction of the oxides with water : Both dissolve to form acid solutions. o
Sulphur dioxide forms the weak 'fictitious' sulphurous acid.
SO2(g) + H2O(l) ==> H 2SO3(aq)
the reaction is better represented ionically as ..
o
-
(aq)
+ HSO3 (aq)
SO3(g) + H2O(l) ==> H 2SO4(l)
In water, the sulphuric acid is almost fully ionised. +
H2SO4(aq) + 2H2O(l) ==> 2H 3O
(aq)
2(aq)
+ SO4
Reaction of oxide with acids: o
H
Sulphur trioxide reacts very violently and exothermically to form the oily liquid, strong sulphuric acid.
+
SO2(aq) + H2O(l)
None, only acidic in nature.
Reaction of oxide with bases/alkalis: o
Sulphur dioxide dissolves in strong bases to form sulphites/sulphate(IV)s
o
2NaOH(aq) + SO2(g) ==> Na2SO3(aq) + H2O(l) formation of sodium sulphite/sulphate(IV)
o
ionic equation: 2OH (aq) + SO2(g) ==> SO3
o
You would NOT attempt to react sulphur trioxide with water, the reaction is very violent and exothermic.
o
but theoretically: 2NaOH(aq) + SO3(g) ==> Na2SO4(aq) + H2O(l)
-
2(aq)
+ H2O(l)
Reaction of element with chlorine: o
When chlorine is passed over molten sulphur a variety of chlorides are formed.
o
The main product is disulphur dichloride
o
2S(s) + Cl2(g) ==> S2Cl2(l) (SiCl2, SiCl4 also possible)
Reaction of chloride with water : o
Slowly hydrolyses in water, via a complex reaction, to form an acid solution of several products (not meant to be a balanced equation).
S2Cl2(g) + H2O(l) ==> HCl (aq), S(s), SO2(aq), H2SO3(aq), H2SO4(aq), H2S(aq) - complex redox/hydrolysis reaction! Z = 17 Chlorine Cl in Group 7/17 The Halogens
The structure of the element: o
Non-metal existing as covalent diatomic molecule, Cl2, with a single bond.
Physical properties:
o
2
2
5
o
HCl and NaCl (-1), NaClO and Cl 2O (+1), NaClO 2 (+3), KClO3 (+5), Cl2O7 and HClO 4 (+7).
Reaction of element with oxygen: None, but there are several oxides made indirectly.
Reaction of the oxides with water :
o
Chlorine(I) oxide forms weak chloric(I) acid. Cl2O(g) + H2O(l) ==> 2HClO (aq)
Chlorine(V) oxide forms the strong chloric(VII) acid.
Cl2O7(l) + H2O(l) ==> 2HClO 4(aq)
Reaction of oxide with acids: o
None, only acidic in nature.
Reaction of oxide with bases/alkalis: o
o
6
Gp7 Halogens; e.c. 2,8,7 or 1s 2s 2p 3s 3p ; (ranges from -1 to +7) e.g.
2
o
o
o
Group, electron configuration (and oxidation states):
o
o
Pale green gas; mpt -101 C; bpt -34 C; poor conductor of heat/electricity.
chlorine(I) oxide forms sodium chlorate(I) with sodium hydroxide,
Cl2O(g) + 2NaOH (aq) ==> 2NaClO(aq) + H2O(l)
ionic equation: Cl2O(g) + 2OH (aq) ==> 2ClO (aq) + H2O(l)
-
-
and chlorine(VII) oxide will dissolve to form sodium chlorate(VII)
Cl2O7(l) + 2NaOH(aq) ==> 2NaClO 4(aq) + H2O(l)
ionic equation: Cl2O7(l) + 2OH (aq) ==> 2ClO4 (aq) + H2O(l)
-
-
Reaction of element with water : o
Slightly reacts to form an acid mixture of chloric(I) acid and hydrochloric acid, but the position of the equilibrium is very much on the left.
Cl2(g) + H2O(l)
HClO(aq) + HCl(aq)
or more accurately and ionically ...
Cl2(g) + 2H2O(l)
HClO(aq) + H3O
+
-
(aq)
+ Cl (aq)
Z = 18 Argon Ar in Group 0/18 The Noble Gases
The structure of the element: o
Physical properties: o
Exists as single atoms, sometimes described as 'monatomic molecules'. o
o
Colourless gas, more dense than air; mpt -189 C, bpt -186 C; poor conductor of heat/electricity.
Group, electron configuration (and oxidation states): o
2
2
6
2
6
Gp0/8 Noble gas; e.c. 2,8,8 or 1s 2s 2p 3s 3p ; no stable oxidation states (other than 0 for the element itself!) so no compounds!
Reaction with anything: o
None! Far too stable electron configuration.
Other comments: o
Last element in the period, as the outer principal quantum level (shell) is full to the maximum number of electrons, conferring extra chemical stability on the atom.
