It is branch if science which deals with the composition, structure qnd properties of matter.
Antoine laurent lavoisier is called the father if chemistry.
Branches of chemistry
1. Inorganic chemistry
Inorganic chemistry is concerned with the study of elements(other than carbon) and their compound.
2. Organic chemistry
Organic chemistry is the beanch of chemistry which concerned with organic compounds or substance produce by living organisms
3. Physical chemistry
Physical chemistry is concerned with the explanation of fundamental principles
4. Analytical chemistry
Analytical chemistry is the branch of chemistry which concerned with qualitative and quantitative analysis of the chemical substances.
In addition to these biochemistry, war chemistry, nuclear chemistry, forensic chemistry, earth chemistry etc., Are other branches of chemistry.
Matter
Anything which occupies some space and have some mass is called matter. It 15 made up of small particles which have space between them. The matter particle attract each other and are in a state of continuous motion.
Physical classification of matter
1. Solid
2. Liquid
3. Gas
Chemical classification of matter
1. Pure substances 2. Mixtures
a. Element
(1) metals
(2) non metals
(3) metalloids
b. Compund
(1) inorganic compound
(2) organic compounds
Elements
It is simplest form of pure substance which can neither be decomposed into nor build from simpler substances by ordinary physical and chemical methods. It contains elements known till date is 118.
Hydrogen is most abundant element in the universe.
Oxygen (46.6%), non metal, is the most qbundant element in the earth crust.
AL is most abundant metal in earth crust.
An element can be a metal or non-metal or a metalloid.
Symbols
A symbol is an abbreviation or shortened form for the full name of an element present aystem of symbols was introduced by Berzelius.
Symbol and latin names of some elements
Elements. Symbol. Latin name
Compound
It is also the form of matter which can be formed by combining two or more elements in a definite ratio by mass. It can be decomposed into its constituent elements by suitable chemical methods, e.g., water (H2O) is made of hydrogen and oxygen in the ratio of 1:8 by mass
Compound can be of two types
(1) inorganic compounds
Previously, it was believed that these compounds are derived from non-living sources, like rocks and and minerals. But these are infact the compounds of all the elements except hydrides of carbon (hydrocarbon) and their derivatives.
(2) organic compounds
According to earlier scientist, these compounds are derived from living source like plants and animals, or these remain burid under the earth (e.g., petroleum). According to modren concept these are hydrides of carbon and their derivatives.
Mixture
These are made up of two or more pure substances. They can be separated into their componants by some physical methods.
Mixture may be homogeneous (when composition is uniform throughout) or heterogeneous (when composition is not uniform throught).
Common methods for the separation of mixture are
(a) filtration filtration is the process of separating solids that are suspended in liquids by pouring the mixture into a filter funnel. As the liquid passes through the filter, the solid particles are held on the filter
(b) distillation distillation is the orocess if heating a liquid to form vapours and then cooling the vapours to get back the liquid. This is a method by which a mixture containing volatile substance can be separated into Its componants.
(c) sublimation This is the process of conversion of a solid directly into vapours on heating. Sunstances ahowing this property are called sublimation, e.g., iodine naphthalene camphor. This method is used to separate a sublimate substances.
(d) crystallization it is a process of separating solids having different solubilities in a particular solvent.
(e( magnetic separation Tills process is based upon the fact that a magnet attracts magnetic componants of a mixture of magnetic and non-magnetic substances. The non-magnetic substance rmains unaffected. Thus. It can be used to separated magnetic componants.
(f) Atmolysis Tills method is based upon rates of diffusion of gases and used for their separation from a gases mixture.
Atom and molecules
Atom is the smallest particle of an element which can take part in the chemical reaction. It major may not capable of independent existance.
Molecule is the simplest particle of matter that has independent existance. It may be monoatomic e.g., H2, cl2 N2 (diatomic) O3(triatomic) or hetroatomic, e.g., HCl, NH3, ch3 etc.
Physical quantities and their measurments units
To express the measurement of any physical quantity two things are considered:
(1) its unit,
(2) the numerical.
Magnitude of physical quantity= numerical value * unit
Units are of two types:
(1) basic units
(2) derived units
1. The basic or fundametal units are those of length (m), ass (kg), time (s) electric current (A), thermodynamic temperature(K), amount of substance (mol), and luminous intensity(cd).
2. Derived units are basically derived from the fundametal units, e.g., units of density is derived from units of mass and volume.
The systems used for describing measurments of various physical quantities are
(a) cgs system it is based on centimetre, gram and second as the units of length, mass and time respectively.
(b) FPS system A British system which used foot(ft). pound (Ib) and second (s) as the fundamental units of length, mass qnd time.
(c) MRS system Uses metre(m) kilogram (kg) and second (s) respectively for lengh mass and time, ampere(A) was added later on for electric current.
(d) SI system (1960) International system of units and contains following seven basic and two supplementary units:
Basic physical quantities and their corresponding basic units
Supplementary units it includes plane angle in radian and solid angle in steradian
Prefixes
The units of some physical quantities are either too amall or too large to change the order of magnitude. These are expressed by using prefixes befor the name of base units. The various perfixes are listed as
Dimension analysis
often while calculating, there is a need to convert unit from one system to other the method used to accomplish this is called factor label method or unit factor methode or dimensional analysis.in in this,
information sought = information given * conversion factio
important conversion factor
scientific notation
in such notation, all measurements (however large or small) are expressed
as a number between 1.000 and 9.999 multiplied or divided by 10. In general as
N*10 here N is known as exponent e g., 138.42 can be written as 1.3842 * 10-4
Precision and accurcy
Precision refers the closeness of the set of vale obtained from identical measurments of quantity. Precision is simply a measure of reproduciblity of an expriment.
Precision = individual vale - arithmetic mean value accuracy = mean- value
In physical measurments, accurate results are generally precise but precise results need not be accurate. Other words good precision does not assure good accuracy.
In measurements accrate results are generally precise results need not be accurate in other words good precision does not assure good accuracy
significant figures
significant figure are meaningfull digits includs all those digits that are known with certainity plus one more is uncertain or estimated
Grater the number of significant figure in a measurment smaller the uncertainity
1. An digit are significant except zero in the beginning of a number.
2. zeros to the right of the decimal point are significant e.g., 0.132, 0.0132 and 15.0, all have three significant figures.
calculations involving
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