Introduction to General and Physical Chemistry

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General and Physical Chemistry
UNIT ONE
Presented By
TEJ NARAYAN CHAPAGAIN
MANIMUKUNDA SECONDARY SCHOOL, BUTWAL, NEPAL
10/16/2020 1TEJ NARAYAN CHAPAGAIN(TNC)

INTRODUCTION TO CHEMISTRY
Chemistry is a branch of science which
deals with the study of composition ,
structure, properties , transformations ,and
application of matter.
Chemist study, discover , reproduce ,and
apply the principles of chemistry for
invention and innovation of better and more
efficient ideas, technologies, processes, and
products for the welfare of life and society.
10/16/2020 TEJ NARAYAN CHAPAGAIN(TNC) 2

WHAT DOES CHEMISTRY?
• Chemistry contributes a way of
understanding the natural phenomena,
traces out the complications and confers the
idea of solution.
• Chemistry has played an important role in
the life of mankind including the fields of
clothing, shelter, pharmacy, agriculture,
food, polymer, explosives, drying,etc.

Chemistry As A Central Science
• Chemistry is often regarded as central science as it
links with other disciplines like biology, physics,
geology, meteorology, environmental science,
material science, medical science, engineering etc.
• Coming up to the 21st century, it has been an era of
technology.
• Nano technology has emerged as an
interdisciplinary field of science and engineering to
introduce smart materials which is mainly guided by
the basic principles of chemistry.

Evaluation
Written exam(theory) + Practical Exam
Theory covers 75 marks
Practical covers 25 marks
Total 100 marks
Question pattern
L.q 20Marks = 2/4 questions 10X2=20
S.q 25Marks = 5/7 question 5x5 =25
V.s.q 30Marks = 15/22 question 2x15=30

Foundation and Fundamentals
General introduction of chemistry
 Importance and scope of chemistry
Basic concepts of chemistry (atoms,
molecules, relative masses of atoms and
molecules, atomic mass unit ( amu), radicals,
molecular formula, empirical formula )
Percentage composition from molecular
formula

General introduction of chemistry
The branch of science concerned with the
substances of which matter is composed, the
investigation of their properties and reactions,
and the use of such reactions to form new
substances.
Chemistry is the scientific discipline involved
with elements and compounds composed
of atoms, molecules and ions: their
composition, structure, properties, behavior
and the changes they undergo during
a reaction with other substances.

What is this?

WHAT IS CHEMISTRY
 Chemistry is the branch of science which deals with
the changes that takes place when atoms or
molecules after interaction undergo transformation
from one form to the another.
 The chemical properties of the substances are
determined through experiments where physical
properties such as pressure, volume, temperature,
concentration , density, time etc., involve the
recording of the a pure number which represents
the following ratio. Pure number= Value of
physical quantity/Value of unit physical quantity

What is this?

Branches of chemistry

Importance of chemistry

Relations

Scope of chemistry
 Importance and Scope of Chemistry
• There are many instances in your day-to-day life that
involves chemistry, its applications, and its rules. Let us look
at them one by one.
 1) Supply of Food
• The study of chemistry provided the world with chemical
fertilizers such as urea, calcium superphosphate, sodium
nitrate, and Ammonium Sulphate. These chemicals have
helped greatly in increasing the yield of fruits, vegetables,
and other crops. Thus, we can cater to the ever-growing
demand for food. It has helped to protect the crops from
insects and harmful bacteria by the use of certain effective
insecticides, fungicides, and pesticides.

 Chemistry also led to the discovery of preservatives.
These chemicals have greatly helped to preserve food
products for a longer period. It has given methods to
test the presence of adulterants. This ensures the
supply of pure foodstuff.
• 2) Contribution to Improved Health and Sanitation
Facilities
 Chemistry provided mankind with a large number of
life-saving drugs. We could find a cure
for dysentery and pneumonia due to the discovery of
sulphur drugs and penicillin. Besides this, life-saving
drugs like cisplatin and taxol are effective for cancer
therapy and AZT is used for AIDS victim. Some of the
common drugs that chemistry has blessed us with
include:

 Analgesics: To reduce the pain of different types.
 Antibiotics: To cure infection and cure diseases.
 Tranquillisers: To reduce tension and bring about calm
and peace to patients suffering from mental diseases.
 Antiseptics: To stop infection of the wounds.
 Disinfectants: To kill the microorganism present in
toilets, floor, and drains.
 Discovery of anaesthetics has made surgical operations
more and more successful.
 The use of insecticides such as DDT and Gammexane
has greatly reduced the dangers of diseases caused by
the rats, mosquitoes, and flies.

3. The Scope of Chemistry in Saving the
Environment
Thanks to science, now we have environment-
friendly chemicals that help us conserve the
nature. One such example is the replacement
of CFCs in the refrigerators.
4.Increase in Comfort, Pleasure, and Luxuries
Because of the advancements in science and
the discoveries of chemistry, we lead a more
comfortable life today. You may ask how? Let
us see below.

• 4) Increase in Comfort, Pleasure, and Luxuries
• Because of the advancements in science and the
discoveries of chemistry, we lead a more comfortable
life today. You may ask how? Let us see below.
• Synthetic fibres: These are more attractive,
comfortable and durable. The include terylene, nylon,
and rayon. They are easy to wash, dry quickly and do
not need ironing. Chemistry provides a large number of
synthetic dyes which imparts bright and fast colour to
the clothes.
• Building materials: By supplying steel and cement,
chemistry helps in the construction of safer homes and
multi-storage buildings. It also helps in the construction
of long-lasting and durable dams and bridges.

• Supply of metals: Metals like gold, silver, copper, iron,
aluminium, zinc and a large number of the alloys are used
for making various objects. These include ornaments,
utensils, coins, and many Industrial and agricultural
implements.
• Articles of domestic use: Chemistry has made our homes
more comfortable by supplying a large number of articles
of domestic uses. Examples include detergents, oils, and
fats, sugar, paper, glass, plastic, paints, cosmetics,
perfumes, cooking gas etc. We are able to beat the heat in
summers by using refrigerants like ammonia, liquid sulphur
dioxide, and freon.
• Entertainment: Cinema, video cameras, simple cameras
make use of films which are made of Celluloid and coated
with suitable chemicals. Fireworks which amuses us on
festival and marriages are chemical products. Can you
imagine how boring life would have been if you wouldn’t
have been able to take all those cute selfies?

• Transport and communication: All means of
transport use either petrol or diesel or coal
which are all chemical products.
• Nuclear atomic energy: Chemistry has come
to the rescue by providing an alternative
source of energy which is nuclear energy.

 5) The Scope of Chemistry in Industry
• Chemistry plays an important and useful role towards
the development and growth of a number of
industries. This includes industries like glass, cement,
paper, textile, leather, dye etc. We also see huge
applications of chemistry in industries like paints,
pigments, petroleum, sugar, plastics, Pharmaceuticals.
• It has also helped in the greater production
of sulphuric acid, nitric acid, and Ammonia,
hydrogenated oils by providing suitable catalysts.
 6) The Scope of Chemistry in War
• Chemistry plays an important role in the discovery of
highly explosive substances such as TNT, nitroglycerine,
and dynamite. It also plays a role in finding poisonous
gases like mustard gas, Phosgene etc.

Q: List down some problems caused by
Chemistry in our society.
Ans:
 Nuclear energy is useful but the disposal of nuclear
waste poses a serious problem to humanity.
 Phonograph records have added to our pleasure for
listening to music but they are made of polyvinyl
chloride. This is produced from vinyl chloride which can
cause liver cancer in industrial workers.
 Antibiotics have eliminated infectious diseases but the
overuse is very harmful. Chemistry has given drugs like
LSD, cocaine, brown sugar. These prove to be a curse to
the society.

Home Assignment
1. What are the uses of chemistry?
2. Is chemistry important in life?
3. Why Is chemistry important for medicine?
4. What is chemistry and its uses?
5.How is chemistry used in medicine?
6.Is chemistry important to become a doctor?
7.Do doctors use chemistry?

8.How is chemistry related to health?
9.What are basics of chemistry?
10.What are the characteristics of chemistry?
11.What are the fields of chemistry?
12.What are three reasons for studying chemistry?
13.What is the future of chemistry?
14.What is the role of chemistry in technology?
15.Will Chemists be needed in the future?
16.Who is chemistry father?
17.What exactly is chemistry?
18.What is full form chemistry?

• What are the uses of chemistry?
• Chemistry plays an important and useful role
towards the development and growth of a
number of industries. This includes industries
like glass, cement, paper, textile, leather, dye
etc. We also see huge applications of
chemistry in industries like paints, pigments,
petroleum, sugar, plastics, Pharmaceuticals.

• Is chemistry important in life?
• Chemistry is important in
everyday life because: ... Many of the changes
you observe in the world around you are
caused by chemical reactions. Examples
include leaves changing colors, cooking food
and getting yourself clean. Knowing
some chemistry can help you make day-to-day
decisions that affect your life

• Why Is chemistry important for medicine?
• Chemistry in Medicine
Major contributions to health care have been
made by chemistry. The development of new
drugs involves chemical analysis and synthesis
of new compounds. ... The chemistry of the
disease must be studied, as well as how the
drug affects the human body. A drug may
work well in animals, but not in humans

• What is chemistry and its uses?
• Article Contents. Chemistry, the science that
deals with the properties, composition, and
structure of substances (defined as elements
and compounds), the transformations they
undergo, and the energy that is released or
absorbed during these processes

Basic concepts of chemistry(contents)
 atoms, molecules, relative masses of
atoms and molecules, atomic mass
unit ( amu), radicals, molecular
formula, empirical formula
 Percentage composition from
molecular formula

Structure of matter
Matter consist of large number of extremely
small particles which may be either atoms or
molecules.
Molecules are further made up of atoms.
So ,the ultimate particle of any element or
compound is atom.

What is this ?

Atom
An atom is the smallest particle of an
element which can take part in chemical
reaction.
Atom may or may not have independent
existence.
The term atom was proposed by John
Dalton.
Atoms are defined as “the basic building
blocks of matter”.

Test your self
1. Atoms of inert gases like helium, argon ,
neon etc have ………………..existence
whereas atoms of hydrogen , oxygen ,
nitrogen etc do not have independent
existence.
2. Atom was considered to be the ultimate
particle of ……………. Which can not be
further subdivided into smaller particles.

What is this ?

Structure of atom
• An atom includes a nucleus, and then a series of orbital
circles that surround this nucleus similar to the solar
system structure.
• The protons and the neutrons reside in the nucleus.
• The electrons are in the orbitals.
• The amount of protons in the nucleus of an atom
determines its atomic number.
• Hydrogen and helium are examples of elements that
have an atom.

About atom
• Atom consist of positively charged nucleus
around which negatively charged
particles(electron) revolve like planet round
the sun.
• The nucleus contains positively charged proton
and chargeless neutrons. These particles are
combinely called nucleons.
• The mass of atom is mainly due to nucleus.

Size of atom
• The atom is about 10-10 meters (or 10-
8 centimeters) in size. This means a row
of 108 (or 100,000,000) atoms would
stretch a centimeter, about the size of
your fingernail. Atoms of different
elements are different sizes, but 10-10 m
can be thought of as a rough value for
any atom.

Dalton’s atomic theory
• All matter consists of indivisible particles called
atoms.
• Atoms of the same element are similar in shape and
mass, but differ from the atoms of other elements.
• Atoms cannot be created or destroyed.
• Atoms of different elements may combine with each
other in a fixed, simple, whole number ratios to form
compound atoms.
• Atoms of same element can combine in more than
one ratio to form two or more compounds.
• The atom is the smallest unit of matter that can take
part in a chemical reaction.

Drawbacks of Dalton's Atomic Theory
• The indivisibility of an atom was proved wrong: an
atom can be further subdivided into protons, neutrons
and electrons. However an atom is the smallest particle
that takes part in chemical reactions.
• According to Dalton, the atoms of same element are
similar in all respects. However, atoms of some
elements vary in their masses and densities. These
atoms of different masses are called isotopes. For
example, chlorine has two isotopes with mass numbers
35 and 37.
• .

Contd….
• Dalton also claimed that atoms of different elements are
different in all respects. This has been proven wrong in
certain cases: argon and calcium atoms each have an
atomic mass of 40 amu. These atoms are known as
isobars.
• According to Dalton, atoms of different elements
combine in simple whole number ratios to form
compounds. This is not observed in complex organic
compounds like sugar (C12H22O11).
• The theory fails to explain the existence of allotropes; it
does not account for differences in properties of
charcoal, graphite, diamond

Merits of Dalton's Atomic Theory
• The atomic theory explains the laws of
chemical combination (the Law of Constant
Composition and the Law of Multiple
Proportions).
• Dalton was the first person to recognize a
workable distinction between the fundamental
particle of an element (atom) and that of a
compound (molecule).

Assignment
What are 5 postulates of Dalton's atomic
theory?
What is Daltons atomic theory?
What are the limitations of Dalton atomic
theory?
Does atom size increase across a period?
What is difference between atom and
molecule?

Assignment
What is the relation between atom and
molecule?
How many atoms are in a molecule?
Which atom is largest in size?
What is an atom? What are atoms made of?

PROJECT WORK
Dear students you are given a project work that
is to be submitted as a part of internal
evalution of grade 11.
 Observe in your surroundings (kitchen, school, shop,
etc.) and make a possible list of organic and inorganic
compounds. How are they different? Why is it
necessary to study them separately, put your
argument?
Last date of submission : 2077/7/30

ROLE OF CHEMISTRY IN COMMUNITY
1.Manufacture of glass ,cement,
fertilizers,dyes,drugs,metal,oil,fuel,pap
er,pesticides used in daily life.
2. Invention of explosives,rocket
fuels,biochemical weapons,bombs etc
3. Analysis of soil,water,,examination of
crime and frauds,etc

MOLECULE
The smallest particle of an element or
compound having independent existence is
called a molecules. For example,
i) H2O represents one molecule of the
compound water
ii) Cl2 represents one molecule of the element
chlorine.
Classifiaction of molecules

Monoatomic atomic molecule-
It consists of only one atom. Example- Noble
gases (He, Ne, Ar, Kr, Xe ), Metals (Na, Fe, etc)
Diatomic molecule-
it consist of only two atoms of same or different
chemical elements. Example- i) two atom of same
element(H2,O2,N2, etc)
ii) two atom of different element(CO,NO )
Polyatomic molecule-
It consist of three or more atoms held together by
covalent bond. It further classfied into
homonuclear and heteronuclear molecule.

a) Homonuclear molecule-
it consist of atoms of same element.
H2-Diatomic molecule
O3-triatomic molecule
P4-tetraatomic molecule
S8-Octaatomic molecule
b) Heteronuclear molecule-
it consist of atoms of different elements.
H2O, NH3, CO2, CH4 etc

Definition of atomic mass
• Atomic mass of an element is the number of
parts by weight of that element which shows
how many times the element is heavier
than1/12th weight of one atom of C-12
isotope. It is denoted by A and its unit is amu
(atomic mass unit).
therefore, A=wt.of an element
1/12 part of C-12 isotope

Atomic mass unit
Mass of one atom of C-12 is assigned 12 amu.
One-twelth (1/12th) of mass of one atom of C-12
is called 1amu.
Now, 1 mol of C-12=12g
or, mass of 6.023x1023 carbon atoms=12g
mass of 1 carbon atom=12/ 6.023x1023
mass of 1/12 carbon atom=1.66x10-24 g
∴1amu=1.66x10-24 g=1.66x10-27 kg
This is called absolute mass of 1 amu.

Fractional atomic mass
 The same element has different isotopes. The percentage
abundance of each isotope in nature is different. Atomic
weight is not the weight of single isotopes. It is calculated by
taking the average weight of different isotopes of an element
according to their percentage abundance in nature. Therefore
, atomic mass is found in fractional number.
 For example, Chlorine exist as two isotopic forms Cl-35(75%)
and Cl-37(25%).
 At.WT = 35X75 +37X25 = 35.5amu
 100

Explain mass number is always whole number
but atomic weight is not whole number.
• Mass number is sum of number of protons and neutrons
present at the nucleus and it is whole number. But, atomic wt.
is calculated by taking the average wt. of different isotopes of
element according to their percentage abundance in nature
and it is fractional. For example: mass number of Mg=
12n+12p= 24
• But atomic mass of chlorine is calculated by taking the
average mass of Cl-35(75%) and Cl-37(25%)
At.WT = 35X75 +37X25 = 35.5amu
100

Question for practice
1.The element Ag consists of two isotopes: Ag-
107 with natural abundance of 51.83% and Ag-
109 with natural abundance of 48.17%. Calculate
the relative atomic mass of Ag.
2. The average atomic mass of hydrogen is 1.008
amu . Calculate the percentage abundances by
mass of protium and deuterium in the natural
mixture of hydrogen.

Molecular mass
• It is defined as the number which shows how
many times the molecule is heavier than
1/12th weight of one atom of C-12 isotopes. Its
unit is amu.
i.e. molecular mass= wt. of molecule

Ionic mass
• It is defined as the number which shows how
many times the ion is heavier than 1/12th
weight of one atom of C-12 isotopes. Its unit is
amu.
i.e. ionic mass= wt. of ion
Eg. Mass of Ca++ is 40
mass of NH4+ is =NX1+Hx4=14+4=18

Ions or radicals
Atom or group of atoms having charge are
called ions. Eg- Na+, CO3
2- ,OH- Cl- etc
The ions having positive charge are called
cations and the ions having negative charge
are called anons. Eg- Na+ is cation ,Cl- is anion
The cation of salt are called basic radicals(
parent base) and the anions of the salt are
called acid radicals( Parent acid) . Eg. Na+ is
basic radical while Cl- is acid radical.

Test question
1.Write two examples of each for monovalent
anions,trivalent cations and monovalent cations.
2.Write two examples of each for divalent
anions,trivalent anions and trivalent cations.

Chemical formula-
• Symbolic representation of a molecule or ion
of a substance is called chemical formula. For
example, H2O is the formula of water
Types of chemical formula-
A. Molecular Formula-
• Definition: An expression which states the number and type
of atoms present in a molecule of a substance.
• Examples: There are 6 C atoms and 14 H atoms in
a hexane molecule, which has a molecular formula of C6H14.

Molecular formula

Empirical formula mass
• The sum of mass of all atoms present in
empirical formula is called empirical formula
mass. For eg,
empirical formula mass of CH2O =12+1X2+16
= 30 amu.
Calculation of common factor(n)
n= molecular mass
Empirical formula mass

Percentage composition
• The percentage of individual atoms of a given
number of moles of molecule, is called
percentage composition.
% composition = wt. of individual atom X100%
molecular wt. of molecule
Q.1. calculate the percentage composition of
each element in sodium thiosulphate(Na2S2O3).

Assignment
1. What is meant by saying that atomic mass of
calcium is 40?
2. How many atoms are in 1g of calcium?
3. How many atoms are in 40g of calcium?
4. How many atoms are in 1g of oxygen?
5. How many atoms are in 1g of sodium?

Introduction to General and Physical Chemistry

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