Page 4 - E-Science Prep.2 2024-2025 t1 Unit1_Neat

Unit 1 Attempts of elements
Lesson1 classification

Classification of elements according to their properties.:-

1. To facilitate (ease) their studies.
2. To find the relationship between elements and their physical and

chemical properties.

The most
important
Attempts

Mendeleev’s - Moseley’s Modern
periodic periodic periodic
table table
table

1- Mendeleev’s table

- It is the first real periodic table
for classifyingelements

At this time, only 67 elements were known

Mendeleev explained his periodic
table in hisbook principle of
chemistry in 1871

2nd Prep. First Term 4