This presentation summarizes key concepts about the periodic table and periodic properties. It introduces Dmitiri Mendeleev and Henry Moseley, who developed the periodic table and periodic law. The periodic law states that when elements are arranged by increasing atomic number, elements with similar properties occur at regular intervals. Periodic properties discussed include atomic radius, ionization potential, electron affinity, and electronegativity, and how they vary across periods and groups in the periodic table.

1. WELCOME TO OUR PRESENTATION

2. Presentation on Chemistry - I
Lecturer
Nazrul Islam
Department of General Education Development (GED)
Daffodil International University , Bangladesh
PRESENTATED BY :
Khokan Chandra Biswas (173-33-4369)
Md . Rezwan Mahmud (173-33-4370)
Md. Munsur Ali (173-33-4399)
Md. Siam Sheikh(173-33-4290)
PRESENTATED TO:

3. Presentation Topic:Periodic law and
periodic properties..

4. Dmitiri Mendeleev
(1834-1907)
Henry Moseley
(1887-1915)

5. Periodic Table
What is periodic table ?
Periodic table is a conceptual diagram of the properties of the
elements expressed in table.
Periodic Law
Mendeleev’s Periodic Law : If elements are arranged
according to their increasing atomic mass , their physical and
chemical properties repeat periodically.
What did Mendeleev miss?
* New elements were discovered ,it became evident that the
periodic table was not in the correct order.

6. Modern periodic Law : When elements are arranged by
increasing atomic numbers , elements with similar chemical and
physical properties occur at regular intervals.
Advantages of the periodic law :
*Easy in the study of chemistry .
*Suggestions for further research become available .
*Predication of new element is possible.
Identify the parts on the periodic table:

7. Periodic Properties
What is periodic properties?
The recurrence of characteristic properties of elements ,
arranged in the periodic table at regular intervals is
called periodicity.
• The periodic properties are :
1. Atomic Radius
2. Ionization Potential
3. Electron Affinity and
4. Electronegativity.

8. What is atomic radius?
The atomic radius of a chemical element is a measure of the
size of its atoms, usually the mean or typical distance from the
center of the nucleus to the boundary of the surrounding cloud
of electrons.

10. What is ionization potential ?
The ionization energy (IE) is qualitatively defined as the
amount of energy required to remove the most loosely bound
electron, the valence electron, of an isolated gaseous atom to
form a cation .

11. Ionization potential across a period:
When moving to the right of a period, the number of electrons
increases and the strength of shielding increases. As a result, it is
easier for valence shell electrons to ionize, and thus the ionization
energy decreases down a group. This is due to electron shielding.
Ionization potential across a group:
1) As you move down a group, first ionization energy decreases.
Electrons are further from the nucleus and thus easier to remove
the outermost one.
2) As you move across a period, first ionization
energy increases.

12. Electron Affinity
Electron affinity is the energy change when gaseous
atom gains an electron to form a gaseous ion.
Electron affinity can either be exothermic or very
endothermic.

13. Electronegativity
What is electronegativity?
Electronegativity is a measure of the
tendency of an atom to attract a
bonding pair of electrons.

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