INTRODUCTION:

Look around you and try to think of logical explanation for what you see in your everyday life. You will start observing common things in uncommon way. Different substances have different forms and appearances: some substances are gases, some are liquids, and some are solids; some are hard and shiny, and some are soft and dull. You will observe that different substances behave differently. Iron rusts but Gold does not; Copper conducts electricity but Sulfur doesn’t. How can these transformations and vast number of other observations be explained?

There are approximately 16 million known chemical compounds, the majority of which are not found in nature. Although many of the known compounds are of little use or importance, some of them would be very essential and difficult or almost impossible to live without these. Imagine… living in a world without concrete, synthetic fibers, fertilizer, steel, soap, glass, or plastics. None of these materials are found in nature in the form in which it is used, and yet they are all produced from naturally occurring raw materials. All of these items are created by different chemical process. But how it is created and from what? That is Chemistry and its application in every day of life.

Chemistry is the study of composition, properties, and transformations of matter.

The branch of science that deals with the identification of the substances of which matter is composed; the investigation of their properties and the ways in which they interact, combine, and change; and the use of these processes to form new substances. (Chemistry. Oxford Dictionaries. Oxford University Press.)

The branch of science that studies the preparation, properties, structure and reactions of material substances is called chemistry. Basic constituents of matter that are atoms and molecules. That is why, chemistry is also called the science of atoms and molecules. (NCERT Textbook)

All matter is composed of one or more of 118 presently known elements.

A matter has a mass and it also occupies space.

A substance is a form of matter having a definite composition and a set of characteristic properties.

There are four fundamental states of matter that are observable in everyday life: solid, liquid, gas, and plasma. However, other states are known to exist in extreme situations. In this class we will study the first three, but you need to be aware of all four of the fundamental states.

There are two broad branches of Chemistry, these are: Inorganic Chemistry & Organic Chemistry.

Chemistry is further divided into several branches as: Physical Chemistry, Analytical Chemistry, Phytochemistry, Biochemistry etc.

If Organic chemistry is considered to be the ‘chemistry of carbon’, then Inorganic chemistry is the chemistry of all elements except carbon. Inorganic chemistry is not simply the study of elements and compounds; it understand us the physico-chemical properties and its changes.

Atom 

Atom is the smallest unit of an element, which can exist either alone or in chemical combination with other atoms of the same or another element. The fundamental composition of atoms are electron, proton and neutron.

Molecule

A combination of two or more atoms

Element 

Substance that cannot be broken down into other substances of different chemical behavior

Compound 

Substance formed from two or more chemical elements by breaking and/or making of chemical bonds

Mixture 

Two or more elements (or compounds) mixed with each other without any chemical bonding

QUESTIONS & ANSWERS

1.      A hypothesis is a

a) process for performing experiments

b) way to describe heat transfer between materials

c) doing something and observing

d) statement or idea that describes or attempts to explain observable information.

2.   An experiment is

a) a controlled testing of the properties of a substance through carefully recorded measurements.

b) an uncontrolled testing of the properties of a substance or system through recorded measurements

c) a one-time reporting of a new observable characteristics

d) a collection of data from an event

3.   A theory

a.  a need for scientist

b. is the result of ideas

c.  the characteristics of individual material

d. predicts the outcome of new testing based on past experimental data

4. John Dalton proposed the first theory on

a.  The rotation of electrons in their shells

b. The characteristics of individual atoms and particles

c.  The presence of elctrons, protons and neutrons in atom

d. All of these

5. A scientific law is best described as

a.  A series of rules made by representatives of the scientific committee

b. A good idea that many people agreed

c.  The transformation of experimental information to public

d. A hypothesis or theory that is tested repeatedly with the same results and thought to be without exception