Fig.1 Some metals give off Hydrogen rapidly.
Reactivity of metals vary widely. If we know the order of reactivity it would be easy to predict chemical reactions. It would be also become easier to remember their properties. Here is the generally accepted Activity series of metals which also include Carbon and Hydrogen for comparison. |
| Li | K | Ca | Na | Mg | Al | C | Zn | Cr | Fe | Cd | Co | Metal |
| 520 | 419 | 590 | 496 | 737 | 578 | 1086 | 506 | 653 | 763 | 868 | 760 | Ionization energy |
| Ni | Sn | Pb | H | As | Cu | Hg | Ag | Pt | Au | Metal |
| 737 | 709 | 716 | 1312 | 947 | 746 | 1007 | 731 | 870 | 890 | Ionization energy |
First let us break this up into groups and learn some common behavior.
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METAL
GROUPS
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REACTIONS
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In air
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With
Water
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Li,K, Ca,Na
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Tarnishes in air.
(stored in Kerosene oil)
Metal + Oxygen
give
metal
oxide.
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Vigorously react in cold.
M + water
Give
M hydroxide + Hydrogen
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Mg,Al, Zn
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Burns in air
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React with steam
M + Water
Give
Mhydroxide + H2
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Cr,Fe, Cd,Co, Ni
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Combine with oxygen slowly
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Rea→→→ct with steam.
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Sn,Pb,H2,As
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Combine with oxygen.
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No
No Reaction
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Cu,Hg,
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Combine with oxygen when heated.
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Ag Pt,Au
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Did you ever wonder , why certain metals are so active while some are very passive.
The activity of an element depends on several factors.
Size of the atom.
- Number of protons and how the electrons are distributed.
- The nature of the reactants
- and The environmental conditions are mainly responsible.
We have an idea of the activity series but according to Lord Rutherford it not science unless we have a way to introduce it in numbers. So is there a way to do that?
There are two factors that can measure according to the accepted units.
They are:-
1. The electrode potential. 2. Ionization energy.
Most metals can lend electrons(Oxidation) to non metals like Oxygen and chlorine.
Sodium atom - electron = sodium ion.
Na - e = Na+
The energy required for this is called ionization energy.
If the ionization energy is low , it would be easier to donate an electron.
This is not the only factor that governs the activeness. For exxample the ability of the other partner to accept electrons is also important.
Reaction with dil. acids and electrode potentials.
Name | E° (volts) | Reactions with dil. Hydrochloric acid. | Reaction with dil. Sulphuric acid. |
Li Lithium | -3.03 |
DANGER | DANGER |
K Potassium | -2.92 | Never Try |
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Sr Strontium. |
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| Never Try |
Ca Calcium | -2.87 |
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Na Sodium | -2.71 |
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Mg Magnesium. | -2.37 | Mg(s) +2 HCl(aq) → MgCl2(aq)+H 2 ↑
| Mg(s) + 2H2O(g) → Mg(OH)2(aq)+H2 ↑ |
Al Aluminium | -1.66 | 2Al +6 HCl →2 AlCl3 +3 H2↑ Very slow start due to an oxide layer. | 2Al + 3H2SO4 → Al2(SO4)3 + 3H2 ↑ |
Carbon |
| No reaction | No reaction |
Zn Zinc | -0.76 | Zn(s) + 2HCl → ZnCl2 + H2 | Zn + H2SO4 → ZnSO4 + H2 ↑ |
Cr Chromium |
| Cr(s) + 2HCl(aq) → CrCl2(aq + H2 Pure metal resists | Cr2 + H2SO4 → CrSO4 + H2 ↑ |
Fe Irion | 0.44 | Fe(s) + 2HCl →FeCl2 + H2 | 2Fe(s) + H2SO4 → Fe2SO4 + H2 ↑ |
Cd Cadmium |
| Cd (s)+ 2 HCl (aq)→ CdCl2 (s) + H2 ↑ Very slow | Cd + H2SO4 → CdSO4 + H2↑
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Co Cobalt |
| Co + 2HCl → CoCl2 + H2↑; | Co + H2SO4 → CoSO4 + H2↑ |
Ni Nickel |
| Ni + 2HCl → NiCl2 + H2↑ | Ni + H2SO4 → NiSO4 + H2↑. |
Sn Tin |
| Sn + HCl → SnCl2 + H2 | Sn +H2SO4 → SnSO4 + H2 |
Pb Lead | -0.13 | Pb(s) +2HCl → PbCl2 + H2 Very slow. | No reaction |
H2 Hydrogen | 0.0 | 2 H2(g) + No reactionO2(g) → 2H2O(l) |
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As Arsenic |
| 4As(s) + 3O2(g) → As4O6(s |
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Cu Copper | + 0.34 |
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Hg Mercury |
| 2Hg + O2 = 2HgO (reversible) |
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Ag Silver | +0.80 | 2 Ag + S → Ag2S 2 Ag2 O → 4Ag + O2 |
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Pt Platinum |
| Pt(s) + 3F2(g) → PtF6(s) [dark red] |
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Au Gold | +1.50 | 2Au(s) + 3Cl2(g) →2AuCl3(s) Forms amalgam with Hg and dissolves in aqua regia | |
Electrochemical Series
| Li | K | Ca | Na | Mg | Al | C | Zn | Cr | Fe | Cd | Co | Metal |
| -3.03 | -2.92 | -2.87 | -2.71 | -2.37 | -1.66 | +0.21 | -0.76 | | -0.44 | | | Electrodde potential |
| Co | Ni | Sn | Pb | H | As | Cu | Hg | Ag | Pt | Au | Metal |
+1.2
Co3+ | -0.05 | +2.0 | +1.8 | 0.0 | -0.2 | +0.15
Cu2+ | +0.85 | +0.8 | + 1.2 | +1.5 | Electrode potential
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Out of all the elements in the Earth almost 80% are metals. Even hydrogen which we normally consider as a non - metal due to its gaseous state is predicted to behave as a metal if frozen to solid state. Metals have a number of common properties but they become very interesting due to their subtle variations.
Remembering the properties of nearly 100 metals is no easy task. This arrangement of metals, ,'Activity Series', according to the ascending order of reactivity, is a boon to students as well as to Industrial chemists.
Any scholar will get enthralled by the beauty of patterns emerging not only from chemical properties but also from completely unconnected factors such as age of discovery and demand. We table here a few of those.
Activity Series and the Discovery of Metals.
Activity series and the cost of metals
Name | Density g/cm3 | Reactions with air | Reaction with Water |
Li Lithium | 0.5 | 4Li(s) + O2(g) → 2Li2O(s)
| 2Li(s) + 2H2O → 2LiOH(aq) + H2(g) |
K | 0.9 | K(s) + O2(g) → KO2(s) K2O also possible | 2K(s) + 2H2O → 2KOH(aq) + H2(g) |
Sr Strontium. | 2.6 | 2Sr(s) + O2(g) → 2SrO(s) 3Sr(s) + N2(g) → Sr3N2(s) |
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Ca Calcium | 1.6 | 2Ca(s) + O2(g) → 2CaO(s) 3Ca(s) + N2(g) → Ca3N2(s) | Ca(s) + 2H2O(g) → Ca(OH)2(aq) + H2(g) |
Na Sodium | 0.97 | 4Na s + O2 g → 2Na2O s | 2Na(s) + 2H2O → 2NaOH(aq) + H2(g) |
Mg Magnesium. | 1.74 | 2Mg(s) + O2(g) → 2MgO(s) 3Mg(s) + N2(g) → Mg3N2(s) | Mg(s) + 2H2O(g) → Mg(OH)2(aq)+H2(g) |
Al Aluminium | 2.7 | 4Al(s) + 3O2(l) → 2Al2O3(s | Very slow reaction |
Carbon | | | |
Zn Zinc | 7.1 | 2Zn(s) + O2(g) → 2ZnO(s) |
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Cr | 7.2 | 2Cr(s) + 3Cl2(g) → 2CrCl3(s) |
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Fe Irion | 7.9 | 4Fe(s) + 3O2(g) → 2Fe2O3(s) | 2Fe(s) + 3H2O(g) Fe2O3(s) +3H2(g) |
Cd Cadmium | 8.7 | 2Cd(s) + O2(g) → 2CdO(s) | No reaction |
Co Cobalt | 8.9 | 2Co(s) + O2(g) → 2CoO(s) |
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Ni Nickel | 6.9 | 2Ni(s) + O2(g) → 2NiO(s) |
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Sn Tin | 7.3 | Sn(s) + O2(g) → SnO2(s) |
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Pb Lead | 11.3 | 2 Pb(s) +O2 (g)→ 2PbO(s) |
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H2 Hydrogen | 0.09 g/L | 2 H2(g) + O2(g) → 2H2O(l) |
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Ar Assenic | 5.8 | 4As(s) + 3O2(g) → As4O6(s |
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Hg Mercury | 13.5 | 2Hg + O2 = 2HgO (reversible) |
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Ag Silver | 10.5 | 2 Ag + S → Ag2S 2 Ag2 O → 4Ag + O2 |
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Pt Platinum | 21.5 | Pt(s) + 3F2(g) → PtF6(s) [dark red] |
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Au Gold | 19.3 | 2Au(s) + 3Cl2(g) →2AuCl3(s) Forms amalgam with Hg and dissolves in aqua regia |
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Activity series and Ionization energy.
110 |
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100 |
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90 |
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80 |
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70 |
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60 |
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50 |
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40 |
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30 x10 | Li 52 | K 42 | Ca 59 | Na 50 | Mg 74 | Al 58 | Zn 51 | Cr 65 | Fe 76 | Cd 87 | Co 76 | Ni 74 | Sn 71 | Pb 72 | As 95 | Cu 75 | Hg 101 | Ag 73 | Pt 87 | Au 89 |
Ionization is the formation of ions from atoms. For a better account click
IonizationQ.1.0
A. Give equations to show how these metals react with chlorine
and water.
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Metal
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Ion
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With
Oxygen
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With water
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Copper
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Cu++
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Cu + O2
→
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Cu + H2O→
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Calcium
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Ca++
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Ca + O2
→
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Ca + H2O→
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Silver
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Ag+
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Ag + O2
→
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Ag + H2O→
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Sodium
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Na+
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Na + O2
→
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Na+ H2O→
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B. Arrange the four metals according to their activity starting from the most active.
15 marks.
Q.2.0
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Metal
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In air
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In Cold water
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A
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Tarnishes slowly
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Bubbles form
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B
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Shine remains for years.
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No reaction
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C
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Tarnishes quickly
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Floats and move about releasing hydrogen.
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D
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Burns when heated.
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No reaction
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Some metals have been named as A,B,C and D. How they reacted in air and with cold water
is given in the chart. RE arrange them according to the activity series taking
the most active one first.
15 maarks
Q.3.0
1. What will be the solid remainder when a sample of Ag2O is heated in air?.
A, Ag, b. O2, . c..N2 d. N2
2. Iron can be obtained by heating an oxide of iron with carbon. What can remain if you heat calcium carbonate with carbon?
a. Ca, b. CaO, c. CaC, d. Ca(OH)2
3. Which metal could produce zinc metal, if heated with zinc oxide?
a. Al., b. Cu c. Fe d. Pb/
4 Which is the correct equation for the reaction of magnesium with hot steam.
a. Mg +H2 O MgO +H2 b. Mg + 2 H2O → Mg(OH)2 + H2
c. 2 Mg + 2H2O → 2MgH2 + O2 d. 2 Mg + 2H2O →2 Mg(OH)2
5. A,B,C and D are 4 metals according to the activity series. A is the most active. Which equation could be predicted as possible.
a. An oxide of A can decompose when heated.
b . If the oxide of C is heated with D we can get the metal C,
c. If D is added to a sulphate solution of B the metal B will be displaced.
d. If C is added to a nitrate of D the metal D will be displaced.
6x5 = 30 marks
Q. 4.0
Select the answers from these words.
Aluminium, Calcium,
Copper, Iron, Lead , Mercury, Potassium,
Silver, Sodium, , Zinc,
1. A
coloured metal that has been used by man since earliest times.
2. Size of
a pea can produce a purple flame on cold water.
3. Fairly
an active metal but widely used in structural work and utensils.
4. Slowly
reacts with water to form a slightly soluble hydroxide.
5. Shows a
reversible reaction with oxygen.
6. Widely
used and a historic era/an age had been given this name.
7. The
yellow oxide of this metal can be reduced by magnesium to give a heavy metal.
8. The
oxide of this gives off oxygen when heated.
9. This is
used to protect iron as a sacrificial metal
10. Very
light , soft and tarnishes instantly in air.
4 x10 = 40 marks
For answers click Answer page - A to K.
