Post on 08-Apr-2018
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Chemistry (Metals & Non Metals):
Metals
Metals have certain characteristic physical properties: they are usuallyshiny (they have
"lustre"), have a high density, are ductile andmalleable, usually have a high melting
point, are usually hard, and conductelectricity and heat. These properties are mainly
because each atom exerts onlya loose hold on its outermost electrons (valence
electrons); On the periodictable, a diagonal line drawn from boron (B) to polonium
(Po) separates themetals from the nonm etals. Most metals are grayish in color, but
bismuth ispinkish, copper is red, and gold is yellow. Some metals display more than
onecolour, a phenomenon called pleochroism.
Non metal
Anon metal is a substance that conducts heat and electricity poorly, is brittle or waxyor gaseous, and cannot be hammered into sheets or drawn into wire. Non metals gain
electrons easily to form anions . About 20% of the known chemical elements are non
metals. The oxides of nonmetals are acidic.
The nonmetals are, in order of atomic number:
hydrogen (H) carbon (C) nitrogen (N) oxygen (O) fluorine (F) phosphorus (P) sulfur (S)
chlorine (Cl) selenium (Se) bromine (Br) iodine (I) astatine (At)
Metalsand Non-Metals
Elements can be classified as metals or non-metals on the basis of their properties.
Physicalpropertiesinclude:
appearance
density
meltingandboilingpointconductivityofheatandelectricity
tensile strength (resistance to bending)
malleability (ability to roll into sheets)
ductility (ability to draw into a wire)
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Chemicalpropertiesinclude:
charge on ions formed from the element
type of bonding found in the element's oxides and chlorides
pHoftheelement's oxide
Metals are found on the left hand side of the Periodic Table while non-metals are found on the
right hand side.
Properties of Metallic and Non -Metallic Elements
Property MetallicElementsNon-
MetallicElements
Appearance
(physicalproperty)lustrous dull
Density(physicalproperty)
moderate to high low to moderate
Physical State
(25oC, 101.3kPa)
(physical property)
solid
(exceptliquidmercury)solid, liquidorgas
Melting and Boiling Point
(physical property)moderate to high wide range
Heat and Electrical Conductivity
(physical property)good poor (exceptgraphite)
Tensile Strength (resistance to
bending)
(physical property)
high brittle
Malleability (roll into sheets)
(physical property)malleable notmalleable
Ductility (draw into wire)
(physical property)ductile notductile
Charge on Ions (in general)*
(chemical property)forms positive ions forms negative ions
Bonding in oxides and chlorides
(chemical property)usuallyionic** covalent
pH of oxides
(chemical property)usually basic*** usually acidic
*some non-metals can form positive or negative ions, eg, H+
and H-
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The Various Kinds of Metals
The Various Kinds of Metals are as shown below:
Properties of Metals
Physical State : Metals are solids at room temp with the exception of mercury and
gallium which are liquids at room temp.
Summary of the Reaction of Metals with Air Water and Acids
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The Reactivity Series of Metals
Physical State
Physical State
Metals are solids at room temperature with the exception of mercury and gallium,
which are liquids at room temperature.
Lustre
Metals have the quality of reflecting light from its surface and can be polished e.g.,
gold, silver and copper.
Malleability
Metals have the ability to withstand hammering and can be made into thin sheets
known as foils.
Ductility
Metals can be drawn into wires. 100 gm of silver can be drawn into a thin wire about
200 meters long.
Hardness
All metals are hard except sodium and potassium, which are soft and can be cut with a
knife.
Valency
Metals have 1 to 3 electrons in the outermost shell of their atoms.
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Conduction
Metals are good conductors because they have free electrons. Silver and copper are
the two best conductors of heat and electricity. Lead is the poorest conductor of heat.
Bismuth, mercury and iron are also poor conductors
Density
Metals have high density and are very heavy. Iridium and osmium have the highest
densities where as lithium has the lowest density.
Melting and Boiling Point
Metals have high melting and boiling point. Tungsten has the highest melting point
where as silver has low boiling point. Sodium and potassium have low melting points.
Electropositive Character
Metals are elements that have a tendency to lose electrons and form cations.
Theynormally do notacceptelectrons.
To summarize: metals are electropositive in nature, lustrous, malleable, ductile, good
conductors of heat and electricity and generally form basic or amphoteric oxides with
oxygen.
Physical Properties of Non-metals
Physical State
Most of the non-metals exist in two of the three states of matter at room
temperature: gases (oxygen) and solids (carbon). These have no metallic lustre, and do
not reflect light.
Nature
NatureNon-metals are very brittle, and cannot be rolled into wires or pounded into sheets.
Conduction
They are poor conductors of heat and electricity.
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Electronegative Character
Electronegative Character
Non-metals have a tendency to gain or share electrons with other atoms. They are
electronegative in character.
Reactivity
They generally form acidic or neutral oxides with oxygen.
Comparative Properties of Metals and Non -Metals
A detailed comparison of properties of metals and non -metals is given in table.
Property Metals Non-metals
Stateofmatter These are usually solid, except
mercury, which is a liquid at
room temperature. Gallium
and Caesium melt below 30
. So if room temperature is
around 30 , they may also
be in liquid state
These exist in all the
three states. Bromine is
the only liquid.
Density They usually have high density,
except for sodium, potassium,
calcium etc.
Their densities are
usually low.
Meltingpoint They usually have a highmelting point except mercury,
cesium, gallium, tin, lead.
Their melting points arelow.
Boilingpoint Their boiling points are usually
high.
Their boiling points are
low.
Hardness They are usually hard, except
mercury, sodium, calcium,
potassium, lead etc.
They are usually not
hard. But the exception
is the non-metal
diamond, the hardest
substance.
Malleability They can be beaten into thin
sheets.
They are
generallybrittle.
Ductility They can be drawn into thin
wires, except sodium,
potassium, calcium etc.
They cannot be drawn
into thin wires.
Conductionofheat They are good conductors of
heat.
They are poor
conductors of heat.
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Conductionofelectricity They are good conductors of
electricity.
They are non-
conductors, except for
carbon in the form of
graphite and the gas
carbon.
Lustre Newly cut metals have high
lustre. Some
gettarnishedimmediately.
Usually not lustrous,
except iodine and
diamond - the most
lustrous of all the
substances.
Alloyformation Theyformalloys. Generally, they do not
form alloys. However
carbon, phosphorus,
sulphur etc. can be
present in some alloys.
Tenacity These usually have high tensile
strength except sodium,
potassium, calcium, lead etc.
These have low tensile
strength.
Brittleness They are hard but not brittle,
except zinc at room
temperature.
They are
generallybrittle.
Electronicconfiguration They usually have 1, 2 or 3
electrons in their valence shell.
The greater the number of
shells and lesser the number of
valence electrons, the greater
is the reactivity of the metal.
They usually have 4, 5, 6
or 7 electrons in the
valence shell. If it has 8
electrons, it is called a
noble gas. Lesser the
number of shells and
greater the number of
valence electrons,
greater is the reactivity
of the non-metal.
Ionization They always ionize by losing
electrons:
They always ionize by
gaining electrons:
Chargeofions Positivelycharged. Negativelycharged.
Typeofvalency Metalsalwaysexhibitelectroval
ency.
Non-metal exhibit both
electrovalency
orcovalency.
Depositionduringelectrol
ysis
They are always deposited at
the cathode.
They are always
deposited at the anode.
Redoxreaction These lose electrons and hence These gain electrons
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get oxidized. and hence get reduced.
Redoxagents They are reducingagents. They are
oxidizingagents.
Natureofoxides They generally form basic
oxides, some of which are also
amphoteric, such as aluminium
oxide, zinc oxide, lead oxide
etc.
They generally form
acidic oxides. Some
oxides are neutral, such
as nitrous oxide, nitric
oxide, carbon monoxide
water etc.
Hydrides They usually do not form
hydrides except those of
sodium, potassium and
calcium.
They do formhydrides,
e.g. NH3, PH3, HCl, HBr,
HI, H2S, H2O etc.
Atomicity These are alwaysmonatomic. These can be mono, di,
tri, or polyatomic.Solubility They do not dissolve in
solvents except by chemical
action.
They dissolve in
solvents and can be re-
obtained by
evaporation. Example:
Sulphurincarbondisulphi
de.
Actionwithchlorine They produce chlorides, which
are electrovalent.
They produce chlorides,
which are covalent.
Actionwithdiluteacids On reaction with dilute acids
they give respective salt and
hydrogen.
They do not react with
dilute acids.
Applications
Some metals and metal alloys possess high structural strength per unit mass, making
them useful materials for carrying large loads or resisting impact damage. Metal alloys
can be engineered to have high resistance to shear, torque and deformat ion. However
the same metal can also be vulnerable to fatigue damage through repeated use orfrom sudden stress failure when a load capacity is exceeded. The strength and
resilience of metals has led to their frequent use in high -rise building and bridge
construction, as well as most vehicles, many appliances, tools, pipes, non -illuminated
signs and railroad tracks.
The two most commonly used structural metals, iron and aluminium, are also the most
abundant metals in the Earth's crust.[6]
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Metals are good conductors, making them valuable in electrical appliances and for
carrying an electric current over a distance with little energy lost. Electrical power grids
rely on metal cables to distribute electricity. Home electrical systems, for the most
part, are wired with copper wire for its good conducting properties.
The thermal conductivity of metal is useful for containers to heat materials over a
flame. Metal is also used for heat sinks to protect sensitive equipment from
overheating.
The high reflectivity of some metals is important in the construction of mirrors,
including precision astronomical instruments. This last property can also make metallic
jewelry aesthetically appealing.
Some metals have specialized uses; radioactive metals such as uranium and plutonium
are used in nuclear power plants to produce energy via nuclear fission. Mercury is a
liquid at room temperature and is used in switches to complete a circuit when it flows
over the switch contacts. Shape memory alloy is used for applications such as pipes,
fasteners and vascular stents.