Chemistry is the study of matter and its interactions. The basic units that make up all matter are atoms, which combine to form molecules. Atoms are made up of protons, neutrons, and electrons. The number of protons in an atom determines its atomic number, while the total mass of an atom is determined by its atomic mass number. Molecules are combinations of atoms that are bonded together chemically. The mole is a unit used to measure amounts of substances, equal to 6.022x1023 particles. Stoichiometry uses mole ratios to calculate amounts of reactants and products in chemical reactions.

1. Some Basic
concept of
chemistry

2. What is chemistry?

4. Physical and chemical method

5. Interaction of atom

7. What is atom?

10. Atomic Number and Atomic mass no. ?

12. ‘Anna, vastra ani nivara’

15. Food Chemistry

16. Cloth
Cloth
chemistry

19. Law of conservation mass
Total masses of reactants =
Total masses of products +
Masses of unreacted reactants.
This law was proposed by Antoine
Lavoisier in 1744

28. Law of indestructibility of matter

30. Law of
definite
proportion
• Joseph proust,
1799

35. John
Dalton
multiple
proportion
1799

37. Gay lussac Law, 1808

39. 1 : 1 : 2

40. 1 : 3 : 1

41. NA = 6.022  1023mol-1

46. 1 volume HCL = n molecule of gas

48. John
Dalton
atomic
model
1799

57. Eg. N→C

58. Atomic mas
• the number of times an atom of
that element is heavier than an
atom of Carbon -12.
• One atomic mass unit is defined
as a mass equal to 1/12th the
mass of Carbon -12 atom.

59. Average atomic mass
• Elements are found in different
isotopic forms (different mass
from)
• Isotope -atoms of same elements
having different atomic mass.
• Average Atomic Mass = Sum of
abundance(rare) of each isotope X
precise atomic mass

60. Example
Isotopes Relative
Masses
Relative
Abundance
(RA)
Cl
35
35 0.755
Cl
37
37 0.245
Average Atomic Mass = 35 x 0.755 + 37 x
0.245 = 35.46 u
There are two isotopes of chlorine.
When atomic mass of any element is reported
in grams, it is called Gram Atomic Mass( GAM)

61. Molecular mass
• The molecular mass of substance (element
or compound) is the number of times the
molecule of the substance is heavier than
1/12ththe mass of an atom of Carbon -12.
• Example:
Molecular mass of H2O = (2 x Atomic mass of
H2) + Atomic mass of O
= (2 x 1.008) + 16.0
= 18.02 u

62. Atomicity
• total number of atoms of elements
combined to form a molecule.
• eg.Atomicity of Oxygen (O2) is two,
while that of Ozone (O3) is three.
Note:
• He and Ne are monoatomic O2, N2 and
H2 are diatomic O3 is triatomic
• P4 is tetraatomic S8 is Polyatomic.

63. Atom is distinguished from its molecule
• Consider the formation of hydrogen chloride from
hydrogen and chlorine.
• Hydrogen and chlorine do not exist in free atomic
state but exist in molecular state hydrogen chloride.
H2 + Cl2 --> 2HCl
[1v] [1v] [2 volumes]
[n molecules] [n molecules] [2n molecules]
½ ½ 1

64. MOLE
• Amount of the substance that contains the
number of particles as present in 12g of C-12.
• This number of particles is determined to be
equal to 6.022 x1023 particles(Avogadro no.N A)
• Atoms and molecules are too small to count. To
solve this problem their numbers are expressed
in terms of Avogadro’s number (NA = 6.023
1023). Mole is the number equal to Avogadro’s
number just like a dozen

66. It is defined as the
percentage by weight of
each element present in
the compound.

67. Percentage composition:
• Eg. C2H5OH , Molecular mass=?, Then %=?
• 2 moles of C atom =12x2 =24g
• 1 mole of O atom = 16 x 1 = 16 g
• 6 moles of H atom = 1 x 6 = 6 g
• Hence, the percentages of constituent
elements are:

68. Percentage composition:
• the percentages of constituent elements are:
• Percentage of carbon = 24 X 100 = 52.17%
• 46
Percentage of oxygen = 16 x 100 = 34.78%
• 46
Percentage of hydrogen = 6 x 100 = 13.04%
• 46
• Therefore, Each 100 g sample of ethanol
contains 52.17 g carbon, 34.78 g oxygen and
13.04 g hydrogen.

69. Empirical
formula

70. Empirical formula:
• chemical formula indicating the number
of atoms in a molecule in the simplest
ratio.
eg.
• The empirical formula of ethanol
(C2H5OH) is C2H6O and that of benzene
(C6H6) is CH.

71. Molecular formula

72. Molecular formula
• The formula which gives the actual
number of each kind of constituent
atoms in one molecule of the compound is
called the molecular formula of the
compound.
eg.
• The molecular formula of ethanol is
C2H5OH and that of benzene is C6H6.

73. Chemical Stoichiometry

74. Chemical Stoichiometry
• Derived from Greek word
• Stoichio – element and
• Metery measure.
• Chemical stoichiometry is a process
of making calculations based on
formulae and balanced chemical
equations.

75. Chemical Stoichiometry
Eg. 1N2(g) + 3H2(g) ⎯> 2NH3(g)
• Numbers 1, 3 and 2 are coefficients.
• 1 mole of N2(g) (28 g) react with 3
moles H2(g) (6 g) giving 2 moles of
NH3(g) (34 g).
• Hence from the amount of the
reactants, the amount of products
that would be formed can be
calculated.

76. limiting and excess reactants

77. limiting and excess reactants
• The limiting reactant.(less amt)
• It is the reactant which is taken as
less that reacts completely, but limits
further progress of the reaction.
• The excess reactant (Large amt)
• It is the reactant which is taken in
excess. Hence, some amount of it
remains unreacted.