CHEMISTRY

Chemistry is the branch of science which deals with the composition , properties and structure of matter.
The word chemistry has derived from the Arabic word Alchemy.
Chemistry does not deal with the states of matter and the form or shapes of matter in which it changed

Branches Of Chemistry :

1= Organic Chemistry:
It is the branch of chemistry that deal with the study compounds of carbon except those which contain carbonate, cynide, and carbon monoxide

2= Inorganic Chemistry
It is the branch of chemistry that deal with the study of all compounds and elements except the carbons and hydrocarbons.

3= Physical Chemistry
It is the branch of chemistry that deal with the study of physical changes of matter and energy changes , formation of mixtures etc.

4= Bio Chemistry
It is the branch of chemistry that deal with the study of chemical changes in the living things like digestion of food in human and the photosynthesis in the plants.

5= Analytical Chemistry
It is the branch of chemistry that deal with the study of chemical analysis of matter, like determination of formula or compounds, determination of cation and anion in salts and percentage of elements in a compound etc.

6= Environmental Chemistry
It is the branch of chemistry that deals with the study of chemical changes of environment like study of atmosphere in moisture, effect of pesticide sprays and industrial exhausted material in the atmosphere.

Matter

Anything which occupy space and has mass is known as matter
In other words it can be say that
"Everything is matter".

Atom
It is the smallest particle of matter or an element is called an atom
The word atom is derived from the word "Atomos" which means uncutable.

Elements
A substance in which all atoms are chemically identical.
Or
A substance in which all atom have some atomic number or number of electron and proton is called an atom.
Examples
Hydrogen, carbon, oxygen, nitrogen, sulphur, chlorine, bromine, lithium, iron, gold, copper, zinc and sodium etc.

Symbols
First or first an other letter of name of element is called symbol. Elements are represented by symbols.
Example
Hydrogen represented by = H
Carbon represented by = C
Oxygen represented = O
Chlorine represented = Cl
Chromium represented = Cr
Nitrogen represented = N
Calcium represented = Ca
Sodium represented = Na
Neo represented = Ne
Potassium represented = K
Iron represented = Fe
Silver represented = Ag
Gold represented = Au
Zinc represented Zn
Mercury represented = Hg
Lead represented = Pb
Sulphur represented = S


Molecules
The smallest unit of substance which has it independent existance is called molecule. Molecules are made up of two or more than two atoms except tha noble gasses because they are inreactive whose molecules monoatomic (made of one atom).

Compound
A substance formed by chemical combination of atoms of two or more elements is called compound.
Or
A substance that contains atoms of different elements in a definite ratio by weight is called compound.
Example
Water, sodium chloride, methane and glucose. Compound can be decomposed into new substance (elements) by chemical methods.

Formula
Symbolic combination of elements of a compound is known as formula.
Compounds are represented by formula.

Mixture
A substance formed by the physical combination of two or more substance is known as mixture.
Example
Mixture of salt amd water, mixture of oil and water, atmosphere is the mixture of different gasses like hydrogen, carbon dioxide, nitrogen, neon and oxygen etc.


Significant Figures

Definition
Digist of the number which gives confidence in measurement is known as significant figures.

Explanation
Significant figures shows the certainty in measurement and decrease uncertainty in it.
Generally greater the number of significant figure in a measurement, more certain is the measurement and less is umcertainty in it

Section Of Insturement Or Device

An insturement with smaller unit give mote number of digits in a measurement and measurement become more certain

Uncertainty In The Last Digit

Last digit of significant figures has an uncertainty of +_1 (Plus, minus One)

Example

Suppose we have the piece of gold to measure its weight and we have two wright balances, one which shows weight in grams and other more sensitive sensitive balance which shows weight in grams and miligrams. Weight of gold on the first weight balance comes 14g, this measurement has two significant digits and uncertainty of plus minus one gram. Now the weight of gold on the second weight balance comes 14.125g in which we have (14g and .125g) this measurement has five significant digits and uncertainty of plus minus 0.001g which is thousand times less than the first uncertainty, thus the second measurement is thousand time more certain than the first measurement.

Rule Of Significant Figures
1= All the non zero digits of the numbers are significant figures.
Example 121 has three significant figures and 1452 has four significant figures.

2= zeros between non zeros digits in a number are significant figures.
Example
104 has three significant figures and 1024002 has seven significant figures.

3= Zeros to the left side of non zero digits are non significant.
Example
0.12 has only two s.f (significant figure)

4= zeros to the right side of non zero digit with decimal point are significan figures.
Example
1.20 has three s.f.

5= last zeros without decimal points are non significant figures.
Example
40000 has only one significant figure.