CONTENT LIST
METALS & NON METALS
PHYSICAL PROPERTIES OF METALS
1. Metals, in their pure state, have a shining surface except Iodine is a non-metal but it is lustrous. This property is called metallic lustre.
2. Metals are generally hard and hardness of metal varies from metal to metal.
3. Metals can be beaten into thin sheets. This property is called malleability.
4. The ability of metals due to which drawn into thin wires is called ductility. Gold is the most ductile metal.
5. Due to malleability and ductility that metals can be given different shapes according to our needs.
6. Metals are good conductors of heat and electricity and have high melting points. The best conductors of heat are silver and copper, Gallium and caesium have very low melting points.
7. All metals except mercury exist as solids at room temperature.
PHYSICAL PROPERTIES OF NON METALS
1. Non-metals are generally brittle. They are neither malleable nor ductile.
2. Non-metals are generally bad conductors of heat and electricity (except graphite).
3. Non-metals are generally non-lustrous (dull) and cannot be polished (except iodine).
4. Non-metals may exist in solids, liquids or gases at room temperature.
5. Non-metals are generally neither tough nor strong.
CHEMICAL PROPERTIES OF METALS
Reaction of metals with Oxygen
Metals combine with oxygen to form metal oxides.
Metal + Oxygen → Metal oxide
Example 1:
When copper is heated in air, it reacts with oxygen to form copper(II) oxide, a black oxide.
2Cu + O2 → 2CuO
Example 2:
When aluminium heated in air, it reacts with oxygen to form aluminium oxide, a black oxide.
4Al + 3O2 → 2Al2O3
Amphoteric oxides
Metal oxides react with both acids as well as bases to produce salts and water are known as amphoteric oxides.
Examples: Aluminium oxide, zinc oxide show both acidic as well as basic behaviour
Example 1:
Reaction of Aluminium oxide with acid.
Al2O3 + 6HCl → 2AlCl3+ 3H2O
Example 2:
Reaction of Aluminium oxide with base.
Al2O3 + 2NaOH → 2NaAlO2+ H2O
Example 3:
Reaction of Zinc oxide with acid.
ZnO + 2HCl → ZnCl2 + H2O
Example 4:
Reaction of Zinc oxide with base.
ZnO + 2NaOH → Na2ZnO2 + H2O
Alkalis
Metal oxides are generally insoluble in water but some of them dissolve in water to form alkalis.
Examples: Sodium oxide and potassium oxide dissolve in water to produce alkalis as follows –
Na2O(s) + H2O(l) → 2NaOH(aq)
K2O(s) + H2O(l) → 2KOH(aq)
Metals react with oxygen at the different rate. They have different reactivity towards oxygen.
Metals like potassium and sodium react so vigorously that they catch fire if kept in the open. That's why to protect them and to prevent accidental fires, they are kept immersed in kerosene oil.
Reaction of metals with water:
Metals generally react with water and produce a metal oxide and hydrogen gas. Metal oxides soluble in water dissolve in it to further form metal hydroxide.
Metals react with oxygen at the different rate. They have different reactivity towards oxygen.
Metals like potassium and sodium react so vigorously that they catch fire if kept in the open. That's why to protect them and to prevent accidental fires, they are kept immersed in kerosene oil.
Metal + Water → Metal oxide + Hydrogen
Metal oxide + Water → Metal hydroxide
All metals do not react with water.
Many Metals like potassium and sodium react violently with cold water. In case of sodium and potassium react so violently and are exothermic that the evolved hydrogen immediately catches fire.
2K(s) + 2H2O(l) → 2KOH(aq) + H2(g) + heat energy
2Na(s) + 2H2O(l) → 2NaOH(aq) + H2(g)
Calcium with water reaction is less violent and the heat generated is not sufficient for the hydrogen to catch fire.
Ca(s) + 2H2O(l) → Ca(OH)2 (aq) + H2(g)
Magnesium does not react with cold water but reacts with hot water and form magnesium hydroxide with hydrogen.
Mg(s) + 2H2O(l) → Mg(OH)2 (aq) + H2(g)
Metals such as aluminium, iron and zinc do not react either with cold or hot water. But they react with steam and form the metal oxide and hydrogen.
2Al(s) + 3H2O(g) → Al2O3(s) + 3H2(g)
3Fe(s) + 4H2O(g) → Fe3O4(s) + 4H2(g)
Metals like lead, copper, silver and gold do not react with water at all.
Reaction of metals with acid:
Reactions of magnesium, aluminium, zinc and iron with dilute hydrochloric acid.
(i) Magnesium reacts with dilute hydrochloric acid and form magnesium chloride and hydrogen gas.
Mg(s) + 2HCl(aq) →MgCl2(aq) + H2(g)(ii) Aluminium reacts with dilute hydrochloric acid and form aluminum chloride and hydrogen gas.
2Al(s) + 6HCl(aq) → 2AlCl3(aq) + 3H2(g)(iii) Zinc reacts with dilute hydrochloric acid and form zinc chloride and hydrogen gas.
Zn(s) + 2HCl(aq) → ZnCl2(aq) + H2(g)(iv) Iron reacts with dilute hydrochloric acid and form iron (II) chloride and hydrogen gas.
Fe(s) + 2HCl(aq) → FeCl2(aq) + H2(g)The rate of formation of bubbles was the fastest in the case of magnesium and most exothermic in this case.
The reactivity decreases in the order Mg > Al > Zn > Fe.
In the case of copper, no bubbles were seen andthe temperature also remained unchanged. This reflects that copper does not react with dilute HCl.
Nitric acid is a strong acid . Metals react with acids to form salt and hydrogen gas, but when metal reacts with nitric acid to form only salt and water and an oxide of nitrogen (NO,N2O,NO2 etc.). because nitric acid is a strong oxidizing agent.
Zn+4HNO3→Zn(NO3)2+2NO2+2H2O
Exception:-
Magnesium and manganese react with very dilute nitric acid to generate hydrogen gas.
The reaction for it is:-
Mg+2HNO3→Mg(NO3)2+H2
Aqua ragia
Aqua regia, (a Latin for ‘royal water’) is a freshly prepared mixture of concentrated hydrochloric acid and concentrated nitric acid in the ratio of 3:1. It can dissolve gold, even though neither of these acids can do so alone. Aqua regia is a highly corrosive, fuming liquid. It is one of the few reagents that is able to dissolve gold and platinum.
Reaction of metal with solutions of other Metal Salts
Reactive metals can displace less reactive metals from their compounds in solution or molten form.
Metal A + Salt solution of B → Salt solution of A + Metal B
In above reaction, metal A displaces metal B from its solution, it is more reactive than B.
Fe+CuSO4→FeSO4+Cu
In above reaction Cu is displaced from its salt copper sulphate by Fe and formed FeSO4 because Fe is more reactive than Cu.
Order of reactivity of metal:
The reactivity series of metals is a chart reflecting metals in order of decreasing reactivity.
K > Na > Ca > Mg > Al > Zn > Fe > Sn > Pb > Cu > Ag
Most reactive metals Na (sodium) is at the top while the least reactive metals at the bottom.
Reactivity of elements is the tendency to attain a completely filled valence shell.
Sample question:
Q1: What happens when you place a Copper strip in a jar containing the MgSO4 solution?
Answer: When we place a copper strip in a jar contaning MgSO4 solution, there will be no reaction. This is beacause copper lies below magnesium in the reactivity series.
Q2: What happens when a Cu coin is dropped in water?
Answer: When a Cu coin is dropped in water, there will be no reaction. This is beacause copper lies below hydrogen gas in the reactivity series.
Q3: Which metal is found uncombined in the Earth's crust?
Answer: Gold is the metal which is found uncombined in the Earth's crust.
Q4: Mention the name of metals which are less reactive then hydrogen.
Answer: Metals which are less reactive then hydrogen are copper(Cu), Silver(Ag), Gold(Au) and Platinum(Pt).
Q5: Two displacement reactions are given below:
A + BSO4 → ASO4 + B
C + ASO4 → CSO4 + A
What is the correct order of reactivity of the metals A, B and C?
Answer: C > A > B.
Q6: On the basis of the given reaction, state weather it is correct or not.
Zinc + magnesium chloride → zinc chloride + magnesium
Answer: The given reaction is not possible. This is because magnesium is more reactive than zinc which can't displace magnesium with its salt solution.
Q7: Why is the reactivity of different metals different?
Answer: The reactivity of different metals different because they have different tendency of loosing the electron.
Q8: Which of the following metals would liberate H2 gas from a dil. solution of HCl? Zn, Ag, Hg Why?
Answer: Among the metals Zn, Ag and Hg, only Zn is more reactive than H2 in reactivity series. So, only zinc will liberate H2 from dil. HCl.
HOW DO METALS AND NON-METALS REACT?
Electrovalent bonds or Ionic bonds are produced when one or more electrons are transferred from atoms of one element to atoms of another element.
Element loosing electrons become cations and another who is getting electrons become anion. Thus the cation and anions hold together with an electrostatic attraction
The bond formed by the transfer of electrons between the atoms is called electrovalent bond or ionic bond.
Electrovalent bonds are formed only between metals and non-metals.
Salt (NaCl) has ionic bond that consists of Sodium (Na) which is a metal with positive charge due to loss of electron that combines with Chlorine (Cl), a non-metal with a negative charge due to gain of electron.
Properties of Ionic Compounds:
- Ionic Compounds have high boiling and melting points that’s why they are very strong and require a lot of energy to break.
- Ionic compounds are found in crystals.
- Ionic compounds are brittle and break into small pieces easily.
- These compound usually dissolve in water and are insoluble in solvents like oil, petrol, kerosene, etc.
- Ionic compounds are bad conductors of electricity in a solid-state but they do conduct electricity in the molten state.
Sample question:
Q1: When is ionic bond formed?
Answer: Ionic bond is formed when metals react with non metal.
Q2: Name a compound having both ionic and covalent bonds.
Answer: Calcium Carbonate (CaCO3)
Q3: Why electrovalent compounds dissolve in water but not in petrol?
Answer: Since petrol is a organic solvent. So, it cannot dissovle any electrovalent compound.
Q4: Give few properties of ionic compounds?
Answer: Properties of ionic compound are:
i) They are polar in nature.
ii) They have high melting and boiling point.
iii) They are soluble in water.
Q5: Why ionic compounds do not conduct electricity in solid state?
Answer: Ionic compounds do not conduct electricity in solid state because cations and anions are closely packed with a strong electrostatic force. That's the reason they cannot move.
Q6: What is the charge on an Aluminium ion?
Answer: The charge present on an Aluminium ion is +3.
Q7: Differentiate between an ionic bond and a covalent bond.
Answer: Ionic compound:
i) They are formed by the tranfer of electron(s).
ii) They have high melting and boiling point.
iii) They are soluble in water.
iv) Aqueous solution of electrovalent compound conduct electricity.
Covalent compound:
i) They are formed by the sharing of electron(s).
ii) They have low melting and boiling point.
iii) They are insoluble in water.
iv) Aqueous solution of covalent compound don't conduct electricity.
Q8: Covalent compounds have low melting and boiling point. Why?
Answer: Covalent compounds have low melting and boiling point because they are formed with sharing of electron(s), so we need very less energy to break these bond(s).
OCCURRENCE OF METALS
Occurrence of metals in combined State
Most of the metals are reactive that's why they do not occur in free elements in nature, they occur in the form of their compounds. The compounds of metals are found in the form of oxides, sulphides, carbonates, chlorides.
Metals which are at the top of reactivity series are more reactive and never found in free state.
Potassium, sodium, calcium, magnesium, and aluminium, which are found on the top of the re-activity series, and are highly reactive and invariably occur in a mixed state. They do not exist in their natural condition.
- Oxides: Copper, zinc, aluminium, iron
- Sulphides: Copper, zinc, silver, lead, iron, mercury, arsenic (As)
- Chlorides: Silver, sodium, potassium, magnesium
- Fluorides: Aluminium, sodium, calcium
- Carbonate: Copper, zinc, lead, calcium, sodium, magnesium
- Sulphates: Barium, calcium, lead
- Phosphate: Lithium, iron, manganese, lead
- Nitrates: Sodium, potassium
Various metals are found
The natural material in which the metals or their compounds are found in the earth crust, they are known as minerals.
Some of them may contain a large percentage of metal whereas others may contain only a small percentage of metal.
Ores are the minerals from which metals can be extracted conveniently and profitably. All ores are minerals but all minerals are not ores.
Extraction of metals
To obtain a metal from its ore is called extraction of metal.
The processes involved in the extraction of metal from their ores and refining is called metallurgy.
- Concentration of ore
- Conversion of ore into metal
- Refining of impure metal.
The three steps involved in the process of metallurgy are:
Occurrence of metals in free or native state
The metals at the bottom of re-activity series are least reactive and also often found in free states.
Metals such as gold, platinum, silver, copper etc. occur in free state because they do not react in presence of air.
Occurrence of metals in free or native state as well in combined state.
Copper is found in both free as well as combined state on Earth in the form of sulphides or oxides ore.
