XI Chemistry - Chapter 1 - Introduction to Chemistry

Chemistry
It is a branch of science which deals with the nature , composition, structure, properties of matter and with the changes which matter can undergo.

Matter

Any thing that has a mass and occupies sapce is known as matter.

Mole

It is the amount of any substane that contain many element entries lile Molecules,atoms, Formula unit as there are the atoms in 12gm carbone - 12


Significant Figures
These are the most relible digit of numbers which are known with certainity.

Rules 1, All non-zero numbers are Signifinant figure:

5294 4 S.F
78899 5 S.F

2, Zeros between non-zero numbers are significant

506804 6 S.F
400001 6 S.F
4010 3 S.F

3, Zeros use in a number less then one to locate the decimal point are notr significant.

0.0004 1 S.F
0.01041 4 S.F

4 Zeros, after decimal are significant

4.000 4 S.F
3.010 4 S.F

5 The numbers which shows the exponent notation are not significant

6.02*1023 3 S.F
5.948*1020 4 S.F




EMPIRICAL FORMUAL
It is the symbolic representation of the compound which contains symbol of the contituting element and the ratio between the atom of these element.

This formula is commonly used for the compound which are ionic in nature and are solid at S.T.P.
For example
The Empirical formula of glucose may be give as,

C2 H6 O2
2: 6: 2




MOLECULAR FORMULA
It is the symbolic representation of the compound which contains symbol of the contituting element and the ratio between the atom and the absolute number of atom of each element present in the molecule of this compoundt.

This formula is commonly used for the compound which are covalent in nature and are found in all three states of matter.
For example
The Molecular formula formula of glucose may be give as,

C6 H12 O6
6: 12: 6

ERROR AND DEVIATION
There are the incorrect or different reading from the actual reading.

Types of error
1 Random error

It is the error which are a result of poor analytical method or defect in instrument.

2 systematic error

It is the error which are a result limitation of instrument or human capability.

stoichiometry

The study of the relationships between amounts of products and reactants.