Lecture 1. BASIC CONCEPTS OF CHEMISTRY.ppt

BASIC CONCEPTS OF CHEMISTRY

1. Lecture 1
BASIC CONCEPTS OF CHEMISTRY
Prepared by PhD Valentina Yuz’kova
Chemistry

2. Chemistry is
 a branch of science that studies
the composition, structure, properties and
change of matter.
Chemistry
Composition Structure Properties

3. Uses of chemistry
medicine
fertilizers
industry
Polymers
soap, detergent
fuels
building materials
water proof and
fire proof
clothes

4. Abuses of chemistry
lead to environmental
problems
Ozone
depletion
Water
pollution
Acid rains
Green house
effect

5. Branches of chemistry
Physical chemistry
Organic chemistry
Inorganic chemistry
Analytical chemistry
Medical chemistry
Bio chemistry
Industrial chemistry
Agricultural chemistry
Geo chemistry

7. Matter
Matter = any material
substance with Mass
& Volume

8. Matter comes in 3 physical states
Physical
state
Shape Volume
solid definitedefinite
liquid indefinitedefinite
gas indefiniteindefinite

10. Element, compound and mixture
Element (simple substance) is a substance consisting of one
type of atom.
Compound (complicated substance) is a substance containing
atoms of two or more different elements joined together.
Mixture is a material system made up of two or more different
substances which are mixed but are not combined chemically.

11. Homogenous and Heterogeneous
Mixtures
Heterogeneous mixture:
•means “different”
•two or more phases present
•you can see the different parts
(phases) of the mixture
Homogenous mixture:
•means “the same”
•single phase present
•you can’t see the different
parts (phases) of the mixture

12. Exercise
• Classify the following into elements and
compounds.
(1)H
2
O; (2) He; (3) Cl
2;
(4) CO; (5) Co.
• Among the substances given below
choose the simple substance, mixtures and
compounds:
(1) Air (2) Sand
(3) Diamond (4) Steel

13. Atom, molecule, ion
Substances are composed of molecules, ions or atoms.
Molecule is the smallest particle in a chemical substance
that has its chemical properties.
H2O
Atom is the smallest, chemically indivisible particle of
substance.
Ion is a charged particle; an atom or a molecule in which
the total number of electrons is not equal to the total
number of protons.
H
O
H
Chemical formula lists the number of different atoms
in a single molecule
Structural formula shows the arrangement of the
atoms in a single molecule

14. atoms
molecules
ions

15. Valency
Valency is the
 number of chemical bonds an atom
can form.
Compound H2 CH4 NH3 H2SO4 Cl2O7
Diagram
ValenciesHidrogen,
1
Carbon, 4
Hydrogen, 1
Nitrogen, 3
Hydrogen, 1
Sulfur, 6
Oxygen, 2
Hydrogen, 1
Chlorine, 7
Oxygen, 2

16. Constant valencies
Element Valency
H I
O II
s-elements of I group and AgI
s-elements of II group and ZnII
Al and B III
F I
Maximal valency of
element (except N, O,
F) = № of group
Valency of nonmetallic
element in binary
compound with
hydrogen = 8- № of
group.

17. Properties of substance

18. Physical properties and their units
Quantifiable
 physical property is called 
physical quantity.
A physical quantity can be expressed as the combination of a
 number 
and a
 
unit
 
.
Most physical quantities include a
 unit, but some are
dimensionless.
Some base physical quantities and their units
Physical quantity Unit Symbol
Length (L) meter m
Mass (m) kilogram
gram
Kg
g
Time (t) second s
Temperature (T) kelvin
degree Celsius
K
⁰C
Amount of substance (ν)mole mol
One mole is the amount of substance that contains as many particles (atoms,
molecules or ions) as there are atoms in exactly 12 g of
12
C isotope (6.02·10
23
).

19. Some other physical quantities and their units
Physical quantity Unit Symbol
Volume cubic meter
litre
m
3
l
Density kilogram per cubic meter
gram per cubic centimeter
kg m
-3
g cm
-3
Pressure Pascal (Newton per square
meter)
atmosphere
millimeter of mercury
Pa (N·m
-2
)
atm
mmHg
Molar mass kilogram per mole
gram per mole
kg mol
-1
g mol
-1
Atomic mass and
Molecular mass
one atomic mass unit
(unified mass)
amu (u)
One atomic mass unit is defined as a mass exactly equal to one twelfth of one
carbon 12 atom.

20. Scientific notation
As chemistry is the study of atoms and molecules which have
extremely low masses and are present in extremely large
numbers, a chemist has to deal with numbers as large as 602,
200,000,000,000,000,000,000 for the molecules of 2 g of
hydrogen gas or as small as 0.00000000000000000000000166 g
mass of a H atom.
This problem is solved by using scientific notation for such
numbers, i.e., exponential notation in which any number can be
represented in the form N·10
n
where n is an exponent having
positive or negative values and N is a number which varies
between 1.000... and 9.999....
Thus, we can write 232.508 as 2.32508·10
2
in scientific
notation. Note that while writing it, the decimal had to be
moved to the left by two places and same is the exponent (2) of
10 in the scientific notation.

21. Basic operations with exponentiation
Multiplication and Division: These two operations follow the same rules
which are there for exponential numbers, i.e.
Multiple Division
Addition and Subtraction: For these two operations, first the numbers are
written in such a way that they have same exponent. After that, the
coefficient are added or subtracted.
Thus, for adding 6.65·10
4
and 8.95 ·10
3
, 6.65· 10
4
+ 0.895 X10
4
exponent is
made same for both the numbers. Then these numbers can be added by
(6.65 + 0.895) ·10
4
.
Similarly the subtraction of two numbers can be done as follows -
2.5· 10
-2
– 4.8· 10
-3
= 2.5·10
-2
-0.48·10
-2
=(2.5-0.48) ·10
-2
= 2.02·10
-2
.
O

22. Some prefixes used in the SI System
Multiple Prefix Symbol
10
-9
nano n
10
-6
micro μ
10
-3
milli m
10
-2
centi c
10
-1
deci d
10 deca da
10
2
hecto h
10
3
kilo k
10
6
mega M
10
9
giga G