М. М. Кутепова The World of Chemistry Мир

Give a short talk on one of the following topics. Make use of the information from the texts you’ve read in Units 1 and 2 and from an encyclopedia.

1. 
   Chemistry as a Science.
   
2. 
   History of Chemistry.
   

UNIT 3

PERIODIC TABLE AND PERIODIC LAW


Grammar: Sequence of Tenses.
Speech Strategy: IMPORTANCE AND CERTAINTY

1. 
   Warming up:
   

1. 
   What would you tell your students about the Periodic Table and the
   Periodic Law as a teacher of chemistry?
   
2. 
   What important information on newly discovered elements can you
   give?
   
3. 
   Have you heard about Element 114? Is it natural or synthesized?
   
4. 
   Complete the following chart with your ideas:
   

i
-| properties
I
~| elements^-
I
-| groups
I
Exchange the information with your fellow students.

2. 
   Listen to or look through the following text and find the facts you’ve not mentioned in the discussion:
   

The story of how D. I. Mendeleyev established the Periodic System of Elements has long been a matter of great interest to research workers.
When Mendeleyev beg^n to teach at St. Petersburg University, chemistry was still far from being the well-ordered and harmonious branch of science that we know today.


|D. I. Mendeleyev|-


|—| THE PERIODIC TABLE
./ I


44


The great majority of scientists were firmly convinced that atoms of different elements were in no way connected with each other, and that they were quite independent particles of nature. Only a few advanced scientists realized that there must be a general system of laws which regulates the behaviour of atoms of each and every element. However, the few attempts made by Beguyer de Chancourtois, Newlands, bother Meyer and others to find a system of laws controlling the behaviour of atoms were unsuccessful and experienced no influence on Mendeleyev, the future founder of the Periodic System of Elements.
“Mendeleyev was a man who could not bear any kind of disorder and chaos,” writes Academician A. A. Boikov. “This is why at the beginning of his course in chemistry at St. Petersburg University, where he had been appointed to the department of chemistry, D. I. had to establish order in the chemical elements.”
By comparison of chemical properties of different elements researchers had long ago discovered that elements could be placed in several groups according to similarity in their properties.
Mendeleyev applied in his system the principles that he developed and included in his table the listing of the elements according to increasing weights.
Because he had the insight to see that many elements had not yet been discovered, he left open spaces in the Periodic Table. For example, he predicted that an unknown element with atomic weight of 44 would be found for the space following calcium. And in 1879 the Swedish chemist Lars Fredric Nilson discovered scandium.
Mendeleyev’s table developed into modern Periodic Table, one of the most important tools in chemistry. The vertical columns of the modern Periodic Table are called groups and the horizontal rows are called periods. The atomic number of an element is the number of protons in the nucleus of the atom of that element. The modern Periodic Table not only clearly organizes all the elements, it lucidly illustrates that they form “f;r lies” in rational groups, based on their characteristics. ³