Chapter 1:Chemical Reaction And Equations
Chapter 2:Acids, Bases and Salts
Chapter 3:Metals and Non-metals
Chapter 4:Carbon and Its Compounds
Chapter 5: Periodic Classification of Elements
Chapter 10: Light Reflection and Refraction
Chapter 11:Human Eye and Colourful World
All the element can be divided into two group on the basis of their property
i)Metal
ii)Non Metal
Metals:
i) Metal are the element that conduct heat and electricity
,ductile and malleable .The samples of
following metals – iron, copper, aluminium, magnesium, sodium, lead,
zinc and any other metal that is easily available.
ii)Metals are the elements which form positive ions by
losing electrons. Thus, metals are known as Electropositive Elements.
PHYSICAL PROPERTIES METALS:
• Hardness: Most of the metals are hard, except alkali metals, such as sodium,
potassium, lithium, etc. are very soft metals. These can be cut by using a knife.
• Strength: Most of the metals are strong and have high tensile strength.
Because of this, big structures are made using metals, such as copper (Cu) and iron (Fe). (Except Sodium
(Na) and potassium (K) which are soft metals).
. lustre Metal have a shining surface. This property is called metallic
lustre
• State: Metals are solid at room temperature except for mercury (Hg).
• Sonorous Metals produce ringing sound, so, metals are called Sonorous.
Sound of metals is also known as Metallic sound. This is the cause that metal wires are used in making
musical instruments.
• Conduction: Metals are a good conductor of heat and electricity..
• Malleability: Metals are malleable. This means metals can be beaten into a
thin sheet. .
• Ductility: Metals are ductile. This means metals can be drawn into thin
wire. Because of this property, a wire is made of metals.
• Melting and Boiling Point: Metals have generally high melting and boiling
points. (Except sodium and potassium metals which have low melting and boiling point.)
• Density: Most of the metals have a high density.
• Colour: Most of the metals are grey in colour. except gold and copper
Non-Metals:
i) Non metal are elements that do not conduct electricity and
heat and they are neither ductility
ii) Non metals are the elements which form negetive ions by gaining
electrons. Thus, metals are known as Electronegetive Elements.
PHYSICAL PROPERTIES NON-METALS:
i) Non metals do not show the properties of
melleabilty and ductile
ii)Non metal do not conduct heat and electricity
iii)Non metal are generally
soft except diamond
iv)Non metal do not so lustrous properties but Iodine is a non-metal but it is
lustrous
v) Non metal have very low melting point and boiling point except diamond
CHEMICAL PROPERTIES OF METALS:
Reaction of metals with air(oxygen):
Almost all metals combine with oxygen to form metal oxides.
Metal + Oxygen → Metal oxide
Reaction of metals with water:
when metals reacting with water to form
metal hydroxide and hydrogen gas
Metal + Water → Metal hydroxide +
Hydrogen
Metal + Steam → Metal oxide + Hydrogen
Metals like potassium and sodium react violently with cold water.
2K(s) + 2H2O(l) → 2KOH(aq) + H2(g) + heat energy
2Na(s) + 2H2O(l) → 2NaOH(aq) + H2(g) + heat energy
sodium and potassium, the reaction is so violent and exothermic
that the evolved hydrogen immediately catches fire.
The reaction of calcium with water is less violent. The heat evolved 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. It reacts with hot water
to form magnesium hydroxide and hydrogen
Mg(s) + 2H2O(l) → Mg(OH)2(aq) + H2(g)
It also starts floating due
to the bubbles of hydrogen gas sticking to its surface.
Metals like aluminium, iron and zinc do not react either with cold or
hot water. But they react with steam to form the metal oxide and hydrogen.
2Al(s) +
3H2O(g) → Al2O3(s) + 3H2(g)
3Fe(s) + 4H2O(g) → Fe3O4(s) + 4H2(g)
Metals such as lead, copper, silver and gold do not react with water at all
When Metals react with Acids:
Metal + Dilute acid → Salt + Hydrogen
Q: when metal react with dilute nitric acid then gas is not form.Why?:
Ans:Hydrogen gas is not evolved when a metal reacts with nitric acid. It is because HNO3 is a strong oxidising agent. It oxidises the H2 produced to water
magnesium (Mg) and manganese (Mn) react with very dilute HNO3 to evolve H2 gas.
Metals react with Solutions of other Metal:
Salts
Metal A + Salt solution of B → Salt solution of A + Metal B
The Reactivity Series:
The reactivity series is a list of metals arranged
in the order of their
decreasing activities
How Do Metals and Non-metals React:
When metal react with non metal
they form ionic compounds
Metals lose valence electron(s) and form cations.
Non-metals gain those electrons in their valence shell and form anions.
The cation and the anion are attracted to each other by strong electrostatic force, thus forming an ionic
bond.
For example: In Sodium Chloride the ionic bond is formed by opposite charged Sodium and chloride ions.
sodium atom has one electron in its outermost shell. If it loses the electron from its M shell then its L
shell
now becomes the outermost shell and that has a stable octet. The nucleus of this atom still has 11 protons
but the number of electrons has become 10, so there is a net positive charge giving us a sodium cation
Na+. On the other hand chlorine has seven electrons in its outermost shell and it requires one
more electron to complete its octet. If sodium and chlorine
were to react, the electron lost by sodium could be taken up by chlorine.
After gaining an electron, the chlorine atom gets a unit negative charge,
because its nucleus has 17 protons and there are 18 electrons in its K, L
and M shells. This gives us a chloride anion C1–
ii)
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Ionic Bond:
The transfer of electron from one atom to another to formed
chemical bond is known as ionic bond
Properties of Ionic Compounds:
Covelent Bond:
The sharing of electron between two atom to formed
chemical bond are known as covelent bond
Properties of Covelent Bond:
i) Covelent compound are usually liquids or gases Some of them are solid (diamond and Silica etc)
ii)Covelent compound have very low melting and boiling points
iii)Covelent compound are insoluble in water but the are soluble in organic solvent
iv)Covelent compound do not conduct electricity
OCCURRENCE OF METALS:
The earth’s crust is the major source of metals.
Seawater also contains
some soluble salts such as sodium chloride, magnesium chloride, etc.
Minerals:
The elements or compounds, which occur naturally in the earth’s
crust,
are known as minerals
Ores:
Msinerals contain a very high
percentage of a particular metal and the metal can be profitably extracted
from it. These minerals are called ores
Extraction of Metals:
The obtain a metal from oresis known as extracted
of metal
Matallurgy:
The process of extracting pure metal form their ores is
called metallurgy
Different techniques
are to be used for obtaining the metals falling in each category
Enrichment of Ores:
Gangue:
The mineral contain large amounts
of impurities such as soil, sand, etc., called gangue.
Extracting Metals Low in the Activity Series:
The oxides of these
metals can be reduced to metals by heating alone.
For example : cinnabar
(HgS) is an ore of mercury. When it is heated in air, it is first converted
into mercuric oxide (HgO). Mercuric oxide is then reduced to mercury
on further heating.
ii) copper which is found as Cu2S in nature can be obtained
from its ore by just heating in air.
Extracting Metals in the Middle of the Activity Series:
Roasting:
The sulphide ores are converted into oxides by heating
strongly in the presence of excess air. This process is known as roasting
Calcination:
The carbonate ores are changed into oxides by heating
strongly in limited
air. This process is known as calcination.
Uses of displacement reaction:
i)Extraction of metals
ii)Manufacturing of steel
iii)Thermite reaction: the reaction of iron(III) oxide (Fe2O3)
with aluminium is used to join railway tracks or cracked
machine parts. This reaction is known as the thermit reaction.
Al(s)+Fe2O3(s)
→ Al2O3+Fe(molten)
Extracting Metals towards the Top of the
Activity Series:
These metals are obtained
by electrolytic reduction
At the cathode (reduction):
Na+(molten) +e- → Na(s)
Metal is deposited.
At the anode (oxidation):
2Cl-(molten) → Cl2(g) + 2e-
Chlorine gas is liberated.
Refining of Metals:
The process of purifying impure metal is called
refining of metal
Electrolytic Refining:
Metals like copper, zinc, nickel, silver, tin, gold etc., are refined electrolytically.
Anode: impure or crude metal
Cathode: a thin strip of pure metal
Electrolyte: aqueous solution of metal salt
From anode (oxidation): metal ions are released into the solution
At cathode (reduction): the equivalent amount of metal from solution is
deposited
Impurities deposit at the bottom of the anode
CORROSION
The eating up of metal by action of air moisture or a chemical
on their surface are called corrosion
Alloy
A homogeneous mixture of two or more metal or metal and non-metal
are called alloy
Examples of alloys –
Brass: copper and zinc
Bronze: copper and tin
Solder: lead and tin
Amalgam
Special class of alloys in which
there is mixture of metal and mercury
Rusting of Iron
Rust is an iron oxide, a usually reddish brown oxide
formed by the reaction of iron and oxygen in the presence of water or air moisture.
4Fe(s)+3O2(from air)+xH2O(moisture)→2Fe2O3. xH2O(rust)
Prevention of Corrosion:
i)The rusting of iron can be prevented by
painting, oiling, greasing,
ii)Galvanisation is a method of protecting steel and iron from rusting
by coating them with a thin layer of zinc
iii)Rusting of iorn can be prevented by alloying it to make
stainless steal
iv)Rusting of iorn can be prevented by tin-plating
Chapter 1:Chemical Reaction And Equations
Chapter 2:Acids, Bases and Salts
Chapter 3:Metals and Non-metals
Chapter 4:Carbon and Its Compounds
Chapter 5: Periodic Classification of Elements
Chapter 10: Light Reflection and Refraction
Chapter 11:Human Eye and Colourful World