3 Part One. The Predicate

The Periodic Table of the Elements
One of the most valuable parts of chemical theory is the periodic law. In its modem form this law states simply that the properties of the chemical elements are not arbitrary, but depend upon the electronic structure of the atom and vary with the atomic number in a systematic way. The important point is that this dependence involves periodicity that shows itself in the periodic rccurrcncc of characteristic properties.

For example, the elements with atomic numbers 2,10,18,36,54, and 86 are all chemically inert gases. Similarly, the elements with atomic numbers one greater— namely 3,11,19,37,55, and 87 are all light metals that are very reactive chemically. These six metals — lithium (3), sodium (11), potassium ( 19), rubidium (37), cesium (55) and francium (87)— all rcact with chlorine and form colourless salts that crystallize in cubes and show a cubic cleavage. The chemical formulas of these salts are similar; LiCl, NaCl, KC1, RbCl, CsCl, and FrCl. The composition and properties of other compounds of these six metals are correspondingly similar, and different from those of other elements.

The horizontal rows of the periodic table are called periods: they consist of a very short period (containing hydrogen and helium, atomic numbers 1 and 2), two short periods of 8 elements each, two long periods of 18 elements each, a very long period of 32 elements, and an incomplete period.

The vertical columns of the periodic table, with connections between the short and long periods as shown, are the groups of chemical elements.

Elements in the same group are sometimes called congcncrs; these elements have closely related physical and chemical properties.
Mashq 4. Agar matndan biron bir yangilik o’rgangan bo’lsangiz ayting?
Mashq 5. Matnni tematik qismlarga ajrating.
Mashq 6. Matn nima haqida ekanligini ayting:
1) davriy jadvalning tuzilishi haqida; 2) davrlar haqida; 3) element guruhlari haqida; 4) elementlarning kimyoviy va fizik xususiyatlarining davriyligi haqida.
Mashq 7. Mantdan davriy qonunning zamonaviy so’z birikmasini toping va uni o’zbek tiliga tarjima qiling.
Section III
Ex. 1. Think of the situations when the following expressions may be used:

it’s a pity; what a pity; not at all; never mind; I’m not surprised; I don’t think so; I have no idea; excuse me (for)

Ex. 2. Translate the sentences into English using expressions from exercise 1.
1. Kech kelganim uchun meni kechiring. - Hechqisi yo’q, men bu yerda uzoq vaqt bo'laman. 2. Petrov sinovdan ikki oldi. "Men bunga ishonmayman." U har doim unga yaxshi tayyorlangan. 3. Ertaga seminarga bormasligim qanday achinarli, bu qiziqarli bo'ladi. – Men unday deb o’ylamayman. 4. Bu haqda menga aytib berganingiz uchun tashakkur. - Arzimaydi. 5. Men ushbu matnni katta qiziqish bilan o'qidim. - U men Mendeleyev haqida gapirsa ajab emas. 6. Ertaga soat 3 da yangi tadqiqot natijalari to'g'risida hisobot bo'ladi. - Men kelolmasligim achinarli, soat uchda ma'ruzam bor. 7. U o'z asarini qachon taqdim etishini bilasizmi? - Menda hech qanday tushuncha yo'q.
Ex. 3. Make up sentences or short stories with the following words: 1) relation, study, weight, property, lead to, periodic, discovery, table; 2) occur, element, order, table, periodic, systematic; 3) consist, isotope, argon, entirely, almost, mass, 40, number; 4) predict, yet, Mendeleyev, discover, existence, which, element, not, six; 5) periodic, horizontal, table, row, consist, call, period, element; 6) vertical, periodic, column, table, group, call
Ex. 4. Give detailed answers to the following questions:

1. What does the periodic law state? 2. How does the periodicity of elements show itself? 3. What do you know about periods of elements? 4. What do you know about groups of elements? 5. Why was the periodic law accepted immediately after its proposal?

Ex. 5. Discuss the following topics:

1. The History of the Periodic System.

2. The Description of the Periodic Table.

3. Predictions Come True.

4. Characteristic Features of One of the Groups of Elements.
DO YOU KNOW THAT...

At present 109 elements are known to the world science, some of them have only hypothetical existence. Attempts are being made to synthesize them in laboratory. Two elements bear the names of great Russian scientists

Mendeleyev and Kurchatov. They are No. 101 (mcndclcvium) and No. 104 (kurchatovium). The development of the science of periodicity was greatly influenced by the synthesis of transuraniums. Ruthenium (No. 44) was named in honour of Russia.