Chemistry is the study of matter, its physical and chemical properties, and the changes it undergoes. There are five basic laws that govern all chemical reactions: conservation of mass, definite proportions, multiple proportions, Gay-Lussac's law of gaseous volumes, and Avogadro's law. According to Dalton's atomic theory, atoms are indivisible and atoms of the same element have identical properties, while compounds form when atoms combine in fixed ratios in reactions where atoms are neither created nor destroyed. The mole concept allows chemists to relate the mass of a substance to the number of particles or entities it contains.

3. Chemistry is the study of matter ,
physical and chemistry
Properties and the physical and
chemistry changes it Undergoes
under different conditions

6. Base physical
Quantity
Symbol for
Quantity
Name of SI Unit Symbol for SI
Unit
Length l metre m
Mass m kilogram Kg
Time t second S
Electric Current I ampere A
Thermodynamic
temperature
T Kelvin k
Amount of substance n mole Mol
Luminous intensity 𝐼𝑣 candela cd

7. There are 5 basic of chemical combinations that
govern every reaction
Law of conservation of mass
Law of definite proportion
Law of multiple proportions
Gay Lussac´s law gaseous volumes
Avogadro law

8. “ Law of conservation of mass
states that matter can neither
Be created nor be destroyed in
A chemical reaction”

9. * Joseph Proust showed that a given
compound always contains exactly
the same proportion of element
by weight
Cupric
Carbon
% of
Copper
% of
Oxygen
%of
Carbon
Natural
sample
51.35 9.74 38.91
Synthetic
sample
51.35 9.74 38.91
𝐶𝑂2
12 16×2
12g C 32 g O
24 G C : 64 g O
36 g C : 96 g O

10. If two elements can combine to form more than one compound
the masses of one element that combine with a fixed mass of the
other element, are in the
Mass of
carbon (g)
Mass of
Oxygen (g)
Ratio of O
in 𝑪𝑶𝟐 to O
in CO
𝑪𝑶 12.01 16.00
𝑪𝑶𝟐 12.01 32.00 2.1
• Carbon combines with oxygen to form
𝑪𝑶 and 𝑪𝑶𝟐
EXAMPLE :

11.  When gases combine or are produced In
a chemical reaction they do so in a
simple ratio by volume provided all gases
are at same temperature and pressure
EX:
Hydrogen (g) + Oxygen (g)
100mL 50 mL
(2vol) (1vol)
Water (g)
100mL
( 2vol)

12. Equal volumes of all
gases at the same
temperature and
pressure contain
equal number of molecules
Example:
Hydrogen (g) + Oxygen (g) Water (g)
100 Ml 50mL 100mL
(2 VOL) (1 VOL) (2 VOL)

13. According to Daltons atomic theory ,
1. Matter consists of indivisible atoms.
2. All the atoms of a given element have identical
Properties including identical mass. Atoms of different
Element differ in mass.
3. Compounds are formed when atoms of different
Element combine in a fixed ratio.
4. Chemical reactions involve reorganization of atoms
These are neither created nor destroyed in a chemical
Reaction.

14. o Masses of atoms , molecules , and formula units are given
In amu (atomic mass unit)
o Example
o Sodium chloride
o (22.99 amu +35.45amu=)58.44amu
o Sulfur dioxide :
o (32.07 amu + 2×16.00 amu =)64.07 amu

15. E
E
E
E
E
E
E
Carbon - 6 Atoms
Atomic Mass = 12
N P
P N

16. Isotopes Atomic mass Relative
Abundance (%)
12 𝐶 12.00000 98.892
12 𝐶 12.00335 1.108
12 𝐶 14.00317 2×10−10
Average atomic mass is the
weighted average of the atomic
Masses of the naturally occurring
isotopes of an element.
= (12 u) (98.892/100) + ( 13.0035 u)
(1.18/100) + (14.00317) (2×10−10
/100)
= 12.011 u

17. Molecular mass Formula mass
Molecular mass of a
molecular is the mas of a
mole of the molecule
Formula mas is the sum of
the masses of atoms
present in the empirical
formula
Calculated from g/ mol units Calculated from amu units
Calculated using the
empirical formula
Calculated using the
empirical formula
Always given the exact
mass of a mole of
molecules
May or may not given the
exact mass of a molecule
Example
• Molecular mass of 𝑂2
mass o 1 molecular = 32 u
mass of 1 molecular of 𝑂2
= 2×16 u
= 32.0 ×1.66056 ×10−24
g
= 53.1379 10−24
× g
Formula mass of NaCl =
Average atomic mass of Na
+ average atomic mass of Cl
=23.0 u + 35,5 u =58.5 u

18. Mole concept Molar mass
One mole is the amount of
a substance that contains
as many entities or particles
as there are atoms in
exactly 12 g (or 0.-12 Kg) of
the carbon -12 isotopes
The mass of one mole of a
substance
(element/compound) in
grams is called its molar
mass
Example ; Example ; 1 mol Na = 23.0
g Na