some basic concepts of chemistry chapter definations
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Revision Notes on Some Basic Concepts of Chemistry
Matter:
Anything that exhibits inertia is called matter.
The quantity of matter is its mass.
Classification of Matter:-
Based on chemical composition of various substances..
Classification of Matter
Elements:
It is the simplest form of the matter.
Smallest unit of an element is known as atom.
Total number of the known elements is 118 out of which 98 elements occur naturally and 20 are formed by artificial transmutation.
Examples: Na, K, Mg. Al, Si, P, C, F, Br etc.
Compound:
It is a non-elemental pure compound.
Formed by chemical combination of two or more atoms of different elements in a fixed ratio.
Examples: H2O, CO2, C6H12O6 etc.
Mixture:
Formed by physical combination of two or more pure substances in any ratio.
Chemical identity of the pure components remains maintained in mixtures.
Homogeneous mixtures are those whose composition for each part remains constant.
Example, Aqueous and gaseous solution.
Heterogeneous mixtures are those whose composition may vary for each and every part.
Example, Soil and concrete mixtures.
Physical Quantities and Their Measurement:
Fundamental Units:-
These units can neither be derived from one another nor can be further resolved into any other units. Seven fundamental units of the S.I. system
Physical quantity
Name of the unit
Symbol of the unit
Time
Second
S
Mass
Kilogram
kg
Length
Meter
m
Temperature
Kelvin
K
Electric current
Ampere
A
Luminous intensity
Candela
Cd
Amount of substance
Mole
Mol
Derived Units:-
These units are the function of more than one fundamental unit
Quantity with Symbol
Unit (S.I.)
Symbol
Velocity (v)
Metre per sec
ms-1
Area (A)
Square metre
m2
Volume (V)
Cubic metre
m3
Density (r)
Kilogram m-3
Kg m-3
Energy (E)
Joule (J)
Kg m2s-2
Force (F)
Newton (N)
Kg ms-2
Frequency (n)
Hertz
Cycle per sec
Pressure (P)
Pascal (Pa)
Nm-2
Electrical charge
Coulomb (C)
A-s (ampere – second)
Measurement of Temperature
Three scales of temperature
Kelvin scale (K)
Degree Celsius scale (oC)
Degree Fahrenheit scale (oF)
Relations between the scales:
oF = 9/5(oC) + 32
K = oC + 273
0 K temperatures is called absolute zero.