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Exploring diversity of matter by it's physical properties - Coggle…
Exploring diversity of matter by it's physical properties
Thermal Conductivity
when we cook food using a frying pan we hold the plastic handle instead of the metal pan
As the plastic handle does not allow heat to flow through it easily, we are able to hold the pan without burning our hands
materials such as plastic are poor conductors of heat
they have low thermal conductivity
as the metal pan allows heat to flow through easily
it feels hot when we accidentally touch it during cooking
materials such as metal are good conductors of heat
they have high thermal conductivity
the thermal conductivity of a material is the measure how easily heat flows through it
Melting Point and Boiling Point
on a hot day, ice cubes change from the solid state to the liquid state.
we say that the ice cubes have melted
the melting point of a material is the temperature at which it changes from the solid state to liquid state
when we heat a kettle of water over a stove
the water changes from the liquid state to the gaseous state
we say the water boiled
the boiling point of a material is the temperature at which it changes from the liquid state to the gaseous state
Strength
a taut metal wire can support the weight of a tightrope walker
we say that the metal wire has high strength
The strength of a material is it's ability to support a heavy load without changing it's shape permanently
however, a metal can can be crushed easily
we say that the metal can has low strength
Hardness
A hard metal can scratch another material that is softer than itself
for example, a piece of glass and scratch a plastic ruler because glass is harder than plastic
there are scratches on a car after it rubs against a wall in a car park
the coat of paint on the car is scratched by the wall as the wall is harder than the paint
Flexibility
rulers made of different materials have different degrees of flexibility
we can blend a plastic ruler easily without breaking it
we may snap a wooden ruler in two when bending it as it is less flexible than a plastic ruler
the flexibility of a material is its ability to bend without breaking, and return to its initial shape and size after bending
electrical cords are flexible and can be coiled without breaking.
A plastic water hose is flexible and thus it is easy to direct the flow of water.
it allows for easy storage when coiled
Density
Determining mass
Mass is the amount of matter in an object. All matter has mass.
the SI unit for mass is kilogram (KG)
other common units of mass are
milligram
tonne
gram
we can use an electronic balance to measure the mass of the substance
the mass of the substance is automatically displayed when it is placed on the metal pan of the electronic balance
Determining volume
Volume is the amount of space an object occupies
the Si unit of volume is the cubic metre
smaller volumes are measured in cubic centimetres
we can use different apparatus to measure the volume of a liquid like
syringe
volumetric flask
measuring cylinder
commonly used to generally measure volume in cm3. however, the volume of a liquid is usually measured in litres or millitres
pipette
beaker
burette
refers to the amount of matter has in the proportion to its volume
objects with lower density float on water
while objects with higher density sink in water
we can determine the volume of an object based on the concept of volume displacement
when the object is fully submerged in water
it displaces an amount of water that is equal to its volume
determining length to calculate volume
the SI unit of length is the metre
other units of length include
centimetre (cm)
millimetre (mm)
kilometre (km)
measuring length
measuring tape
we can use a measuring tape to measure longer lengths or lengths of curved surfaces
A measuring tape can be used to make measurements in our home
A measuring tape can be used to measure the length of a curved surface in tailoring
digital calipers
often used to measure short lengths and diameters of small objects.
they display the length as a numeric value on their display
we can use them to measure the internal and external diameters of an object
We can also use the tail of the digital caliper to measure the depth of an object
test tube
cap of a pen
container
determining density
the density of an object or a substance is defined as its mass per unit volume
mass
volume
density
The SI unit of density is kilogram per cubic metre (kg/m3)
can also be expressed in grams per cubic centimetre (g/cm3)
the density of an object affects its ability to float or sink
if the object has a density higher than the density of water it will sink
if the object has a lower density than the density of water it will float
Electrical conductivity
electrical conductors allow an electric current to flow through them easily
examples include copper and iron
materials like rubber and plastics are electrical insulators
they do not allow electric current to flow through them easily
they have low electrical conductivity
The electrical conductivity of a material is the measure oh how easily an electric current flows through it
main class of materials
glass
poor conductor of heat
can be moulded into shapes
poor conductor of electricity
has a high melting point
transparent
fragile
plastic
can be moulded into shapes
has a high melting point
does not corrode
poor conductor of heat
lightweight
poor conductor of electricity
metal
good conductor of electricity
good conductor of heat
shiny
can be moulded into shapes
can be bent without breaking
fibres
can be spun into threads and woven into fabrics
able to absorb dyes
poor conductors of electricity
poor conductors of heat
ceramic
can be moulded into shapes
does not corrode
hard
has a high melting point
poor conductor of electricity
made from clay
fragile