Physical Properties of Metals and Non-Metals, Class 8 Science Video Lecture

hello friends this video on metals and
nonmetals part three is brought to you
by exam for calm no more fear from exam
so now we are going to talk about the
physical properties of metals now when I
say physical properties I am talking
about the properties which are
externally visible so the first property
of metals that we are going to talk
about is the metallic luster so what do
we mean by russchid so we say that
metals in their pure state have a less
trip when I'm say last year it means a
shining surface so if you look at metals
in their pure form so please remember
this so when they are not mixed with
anything else so in their pure form they
will always have a shiny surface and
this does a property which is
exclusively present for metals now if
you want you can just try this out
yourself so what you have to do is you
take small pieces of iron copper
aluminium or magnesium so these kind of
metals you take and just look at the
appearance of their surface now what you
do
clean the surface of each of these
samples by rubbing with a sandpaper you
know what to sandpaper so sandpaper
generally if you go to any shop and ask
for sandpaper they'll give it to you it
will be a paper with a rough surface and
it is used for cleaning the metal
surfaces so once you clean it and now
you again observe their parents on their
surface and you will see that the
surface is very very shiny so in fact
for gold and silver you can actually see
I mean we actually know how shiny it is
the gold jewelry silver jewelry however
they are mixed with some other things
also in order to provide rigidity to it
but still these metals have a lot of
luster in them so metallic luster is a
property or a physical property of
metals next is hardness now metals
generally are hard
however the hardness might vary from one
metal to another so one metal might be
more hard some other metal might be
quite soft but
as such metals when compared to non
metals they are hard so let us take some
examples now you will observe that there
are metals like sodium if you consider
metal like sodium you will see that they
are comparatively soft when compared to
other metals like iron copper aluminium
magnesium so if you look at these metals
they are hard compared to sodium which
is which is kind of soft so what kind of
activity you can do maybe you can take
one of these metals and you just try to
break the metal with the help of a knife
and what do you see you will see that
you are not able to do it because the
metal is quite hard but if you try the
same experiment with a piece of sodium
in that case you will see that the so
you will be able to cut the piece of
sodium it shows that sodium is
comparatively softer when compared to
iron copper aluminium magnesium gold or
silver
so in general metals and hard now
whatever physical properties we are
going to talk about now that doesn't
mean that all metals are going to have
the same property there are exceptions
to it there are variations even within
the metal for example as far as hardness
is considered not all metals are equally
hard for example even if you compare
either or copper or magnesium they are
not equally hard some some of them is
harder than the other so the hardness
varies from one waited to another
similarly there might be certain
exceptions where the metals are not hard
they're like kind of soft for example
sodium so that and that is the reason
why metals are substances are not
classified as metals and nonmetals based
on the physical properties because there
are too many exceptions to it there are
a lot of variations in it they are for
the definition of metal and no
is somebody who has a tendency to lose
electrons will be classified as wagons
the next property is manual ability so
what is malleability now this is the
property by which metals can be beaten
into thin sheets now what do we mean by
that what we mean by clean sheets now
have you ever used aluminium foil for
wrapping your food like when you pack
your lunch box have you seen that a tin
foil is used for a wrapping of the food
so what does that foil made upon the
foil is made up of aluminium in fact you
would have seen these kind of boxes also
so how do you get such thin sheets out
of a hard metal like aluminum so that
shows that aluminium is a property that
it can actually beaten into thin sheets
now how do you beat it you just take a
small example take a hammer and take any
metal object maybe and either mail or a
small piece of aluminium if you have any
in your house and you start beating it
with the hammer
now when you repeatedly beat it with a
hammer what will you see so what you
would see what what you would most
likely see is the metal changes in shape
now as you beat it wherever it tend to
become deformed in that portion so
basically on beating metals they are
able to change their shape so when you
vigorously beat it it might even turn
into thin sheets and that is how it
happens in case of aluminium now not
only aluminium foil so aluminium foil is
just one example
so aluminium foil is one example which
shows the property of malleability
another example would be the silver foil
which is used for decorating sweets if
you go to a sweet shop you see a lot of
sweets have a thin silver foil over it
so that silver foil is also obtained
from silver so the silver metal is
actually beaten into extremely thin
sheets and that's how we get it so this
shows that and this property is present
again exclusively in metals so if you
try to compare and if you try to look at
a similar property in case of non metals
you will see that they do not have this
property now when we talk about
nonmetals we will talk about each of
these properties again and show that how
they do not have it so this property of
malleability can be seen in a lot of
metals like aluminium silver iron zinc
or / etc however gold and silver are the
most malleable metal metals and needless
to say that is why because of this much
of flexibility they are used to design
so many jewellery of different shapes
and designs and so if you look at a gold
necklace or a bangle so they all have
different designs and they are all made
up of wood so that has been possible
because gold can be manipulated they are
in two different type of shapes so gold
and silver our most valuable metals
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