leedercools

07.12.2020 10:21 •  Английский язык

closely related to the other elements in its group. In order to understand better these groupings,
chemists have tried to fit the elements into a single plan.
One of the earlier attempts to fit the relationships among the elements into a single law was
made by John Newlands in England, who suggested the Law of Octaves.
This concept of the periodic repetition of properties was further developed by a Russian chemist
Dmitri Mendeleyev who created a Periodic Table in which he arranged the elements according to
their atomic weights and corresponding chemical properties.
D.I. Mendeleyev listed the elements known at the time (1869) in the order of their atomic
weights from the lightest to the heaviest. The elements were arranged in a table of eight columns;
elements having similar properties appeared in the same columns or groups in the table.
Mendeleyev even predicted that there were undiscovered elements and left empty spaces3 in this
table for the new discoveries.There are many ways the Periodic Table can be used. The table can
be used to find the atomic number.
The atomic weight is also indicated in the table. The orbital arrangement of electrons is
shown for each of the elements. The common oxidation states are given. For most elements these
numbers are the same as the valence numbers. The table enables us to recognize families of
elements. For example, copper (29), silver (47), and gold (79) will all be found in the same
column.
They have similar properties and are considered a chemical family. And at last the table
can be used to predict the properties of the elements. The fact that the Periodic Table can assist
in predicting properties of elements has helped in the discovery of missing elements.
Answer the following questions.
1. What certain natural groupings are there among the chemical elements?
2. What have chemists tried to do in order to understand better these groupings?
3. Who made one of the first attempts to fit the relationships among the elements?
4. Who developed the concept of the periodic repetition of properties?
5. What columns are there in the Periodic Table?
6. What did Mendeleyev predict?
B 1. Read the text statements and write if they are true ( T ) or false ( F )?
1. In order to understand better these groupings, chemists haven’t tried to fit the elements into a
single plan.
2. This concept of the periodic repetition of properties was further developed by a Russian
chemist Dmitri Mendeleyev.
3. Dmitri Mendeleyev created a Periodic Table in which he arranged the elements according to
their atomic weights.
4. D.I. Mendeleyev listed the elements known at the time (1869) in the order of their atomic
weights from the heaviest to the lightest.
5. The elements were arranged in a table of seven columns.
6. Mendeleyev even predicted that there were undiscovered elements and left empty spaces3 in
this table for the new discoveries.
C 1. Find the Russian equivalents to the following English words and word combinations.
Make three sentences with these words.
1. is closely related to a) пустое пространство
2. to fit the relationships б) установить связь
3. empty space в) недостающие элементы
4. the orbital arrangement of electrons г) тот же самый
5. the same д) расположение электронов на орбите
6. missing elements е) тесно связан