By Ms.
Janani Rodrigo
What are metals?
Common properties of metals.
Alloys.
Different types of metals.
I. Iron.
II. Steel.
III. Gold.
IV. Copper.
V. Aluminium.
VI. Titanium.
VII. Mercury.
Metals are very useful materials.
Metals have contributed greatly in
development of civilisations- from
weapons for survival to constructing
buildings and massive structures
like bridges today.
Weapons made from rocks and
metal by the early humans
The first ever metal used by man is
considered to be copper over
10,000 years ago.
Majority of the metals have shared
properties with each other.
How they differ from one another is
through small differences in these
Golden gate bridge Califonia,USA
shared properties.
How many different uses of metal can you spot?
What are the general properties of most metals?
solid at room temperature
high melting point
good conductors of electricity and heat
malleable: they can be shaped
ductile: they can be drawn into wires
Strong and tough(do not shatter when dropped
and do not crack)
Some metal are magnetic. (iron, steel, nickel
and cobalt)
State of metals: All metals
exist in the solid state at room
temperature except for
mercury.
Luster: metals are shiny
when freshly cut, scratched or
polished. Freshly cut shining metal
surface
Hardness: Metals are hard
and tough and do not shatter.
Copper metal blocks
Malleability: Ability of metals to
change shape under pressure and
made into thin sheets without
breakage.
Ductility: Ability of metals to be
drawn into wires without breaking.
Ex: 100 g of silver can be drawn
into a thin wire about 200 meters
long
Gold and aluminium foils
This property of metals is highly
used in manufacturing electrical
wires, wire ropes for elevators
and in jewellery making.
Metal wires
Conductivity: Metals are good conductors of heat and
electricity. Ex:Silver and copper (best conductors of heat
and electricity).
Where do you use the property of electrical conductivity?
This is another important property that is mainly
considered when manufacturing electrical wires.
Thermal conductivity can be observed by touching a
metal.
Copper electrical wires Silver electrical wires
Melting point: Metals have high
melting points except for Mercury.
Tungsten has the highest melting
point and hence used in light bulbs.
Can you remember what is
melting point?
Magnetic properties of metals:
Tungsten filament in a bulb
Some metals such as iron, steel.
Nickel and cobalt have magnetic
properties.
Magnetism is a basic force of nature.
An object containing this force is
known as a magnet.
These magnets attracts materials A magnet with north and south poles
with magnetic properties. creating a magnetic field observed with
iron filings
Sonority: Metals produce a ringing sound when
struck hard. The metals which produce this sound is
said to be sonorous.
Sonority is used in a gong Sonority is used in a bell
An alloy is a combination of a metal
with at least one other metal or a non-
metal.
The most common way to combine metals
into an alloy is by melting them, mixing
them together, and then allowing them to
solidify and cool.
Examples for alloys: Steel (Iron with
Brass Sri Lankan oil
carbon), white gold (gold and silver), lamp
brass (copper and zinc).
Alloys are made to increase the metals
hardness, strength, corrosion resistant.
There are different types of metals with different special
properties that makes them ideal to be used in doing variety
of work.
Iron
Steel
Mercury (an alloy)
Different types
Titanium of metals
Gold
Copper
Aluminium
This old-fashioned metal (most commonly
used during the iron-age) still have modern
uses.
Iron can be abundantly found on the earth
crust (approximately 5% of earth’s crust)
In the early days iron was used as wrought
iron mostly but with the discovery of steel,
now iron is highly used in manufacturing
steel.
Iron in its pure form rapidly corrodes from Eiffel tower
exposure to moist air and high
temperatures.
Iron is a magnetic metal and therefore used
in producing magnetic materials.
Iron is a very hard metal and this property is
used in making massive structures like the
Eiffel tower.
Sainte- Genevieve library, France
Steel is produced by combining iron with carbon. Steel is
more hard and stronger than iron and resistant to corrosion.
Steel has become by far the most widely used
material for building the world’s infrastructures and
industries.
Stainless steel is highly resistant to corrosion and therefore
used in manufacturing medical equipments, and food
related equipments.
Building infrastructure medical equipments stainless steel pans
Gold is a precious metal.
Not abundantly found on the earth’s
crust.
This metal is attractive in colour and
brightness, highly malleable and
ductile and usually found in its pure
form in the nature. Gold mask of king Tutankhamun
High malleability and ductility of this
metal makes it ideal in shaping it into
different designs when making
jewellery.
Gold jewellery
It is a good conductor of electricity and heat.
This metal does not tarnish or corrodes and therefore
it is durable.
All of these properties of gold caught human attention
from early days and has been accepted as a universal
currency for exchange of materials and services.
Copper is considered as the first ever metal found by
humans.
This metal is highly malleable, extremely ductile and a
very good conductor of electricity and heat.
Due to these properties of copper, it is highly used in
electrical industry in producing electrical wires and
motors. And also in industrial machinery such as heat
exchangers.
Copper wires Copper in an electrical motor Copper heat exchanger
Aluminium is a silvery-white metal that is the second most
abundantly used metal in the world.
It is lightweight, highly malleable and ductile, good electrical
and thermal conductor and has a high corrosion resistance.
Aluminium is a strong metal but it is often used combined
with other metals as alloys to make it even more stronger.
High malleability and strong but lightweight nature of
aluminium makes it the ideal metal to use in construction of
aeroplanes and other forms of transportation.
Other uses of aluminium include producing cans, kitchen
utensils, window frames, foil.
Aluminium cans
Aluminium is highly used in making aeroplanes
Titanium is named after the titans in Greek mythology.
This metal is hard, shiny, as strong as steel but lightweight.
Often used in building high speed aircrafts, spacecrafts and
missiles.
Titanium has a very low electrical and thermal
conductivity. It is highly corrosion resistant specially to
seawater and therefore highly used in making ships,
submarines and other structures exposed to seawater.
Due to its high corrosion resistant, titanium is considered
biocompatible and used as a biomaterial in surgery and
different transplants.
Titanium alloys are used in building high speed aircrafts Titanium as a biomaterial
Mercury is the only metal exist in the liquid state.
Gold and silver metals dissolve in mercury. In the past this
property was used in the extraction of these metals.
Mercury is highly used in thermometers as this metal
doesn’t wet the wall or cling on to it.
Mercury readily combine with other metals to form alloys
known as amalgams. Amalgams have been used as dental
fillings in the past but are greatly reducing now due to safety
concerns.
Mercury is also a good electricity and heat conductor. Due
to its high toxicity, use of mercury is limited.
Amalgams as dental fillings Mercury metal existing in a liquid at room temperature
Goodbye
Stay safe!
