Attempts of elements classification
Lesson objectives
- At the end of the this lesson, the student should be able to:
1-Recognize the efforts of some scientists to classify elements.
2-Determine the location of some elements in the modern periodic table by recognizing their atomic numbers
3-Deduce the atomic numbers of some elements by recognizing their locations in the modern periodic table.
4-Estimate the importance of discipline and organization in our life.
5-Estimate scientists efforts in discovering , classifying and investing elements.
1-Mendeleev’s table
Mendeleev predicted the ability of discovering
new elements. So he left spaces(empty cells) in his table, and he corrected the
wrong estimated atomic weights of some elements. He had to make a disturbance
in the ascending order of atomic weights for some elements, due to putting them
in groups which suit their properties, and he also would have to deal with the isotopes
of one element as different elements because they are different in their atomic
weights.
- Moseley’s periodic table
In 1913, the Newzealand Scientist Rutherford discovered that the nucleus of atom contains positively charged protons, the British Scientist Moseley discovered in the same year after studying the properties of x rays that the periodicity of elements properties is related to their atomic number not their atomic weights as Mendeleev believed So Moseley rearranged the elements in an number such that the atomic number of an element increases by one than the element.
- The modern periodic table
After the Danish Scientist Bohr discovered the main energy level
- elements have been classified according to:
1- the atomic number
2- the way of filling energy sub level with electrons
- In the modern periodic table
1- The number of known elements until now are 116 elements, 92 elements are abundant in the earth’s crust, the rest of the elements are prepared artificially
2- Elements of (A) groups lie on the left and right of the table, you can locate their position in the modern periodic table
by knowing their atomic numbers and vice versa. The elements of (B)
groups lie in the middle of the table.
- please visit this video because it shows this lesson in detail:
- To know elements in the modern periodic table visit these links
*Blocks of elements in modern periodic table
جميل جزاك الله خيرا
ردحذف