Match the notions and their definitions.

1. Angstrom	a) in optics, the arrangement according to wavelength of visible, ultraviolet, and infrared light
2. Atom	b) flow of atomic and subatomic particles and of waves, such as those that characterize heat rays, light rays, and X-rays
3. Nucleus	c) the quantity of matter contained in an atom of an element, expressed as a multiple of one-twelfth the mass of the carbon-12 atom, 1.9924 × 10−23 g, which is assigned an atomic mass of 12 units. In this scale, 1 atomic mass unit (amu) corresponds to 1.6603 ×10−24 g
4. Alpha particle	d) unit of length used chiefly in measuring wavelengths of light, equal to 10-10 metre. It is named for the 19th-century Swedish physicist Anders Jonas Ångström. The symbol is Å. The angstrom and multiples of it, the micron and the millimicron, are also used to measure such quantities as molecular diameters and the thickness of films on liquids
5. Spectrum	e) ratio of the average mass of a chemical element's atoms to some standard
6. Atomic number	f) discrete natural unit, or packet, of energy, charge, angular momentum, or other physical property
7. Atomic weight	g) smallest unit into which matter can be divided without the release of electrically charged particles. It also is the smallest unit of matter that has the characteristic properties of a chemical element. As such, the atom is the basic building block of chemistry
8. Atomic mass	h) positively charged particle, identical to the nucleus of the helium-4 atom, spontaneously emitted by some radioactive substances, consisting of two protons and two neutrons bound together, thus having a mass of four units and a positive charge of two
9. Quantum	i) the number of a chemical element (q.v.) in the periodic system, whereby the elements are arranged in order of increasing number of protons in the nucleus
10. Radiation	j) the core of an atom

Read the passage and decide if the sentences below are TRUE or FALSE? If one of them is TRUE put Т next to it, if it's FALSE put F.

1. Thomson showed that the atom has a small, heavy nucleus.

2. Rutherford's nuclear model was suspected by many scientists.

3. According to Nagaokaan electron could remain in any particular orbit indefinitely.

4. British physicists, such as Charles Glover Barkla, Sir William Bragg and his son Lawrence examined the spectra of X-rays using a crystal of potassium ferrocyanide as a diffraction grating.

5. Moseley’s formulas for the X-ray frequencies were connected with Bohr's formulas for the spectral lines in a hydrogen atom.

6. Bohr designed his atomic model specifically to explain the hydrogen atom.

 

Match numbers 1-10 with letters a-j to make collocations. Then use these collocations in the sentences of your own.

1 regular a) model

2 inherently b) frequencies

3 photographic c) pattern

4 nuclear d) atom

5 spectral e) difference

6 diffraction f) stable

7 X-ray g) lines

8 energy h) plate

9 radiant i) grating

10 hydrogen j) energy

Explain the meanings of the following verbs. Then use them in the text of your own (10-12 sentences).

1. to adapt

2. to embed

3. to attempt

4. to resemble

5. to overturn

6. to refine

7. to deflect

8. to detect

9. to scatter

10. to reconcile

11. to impact

2.6.Mind the translation of the verbs "to follow" and "to precede" in the Passive Voice.

-to follow-

- следовать за кем-, чем-либо

- придерживаться (теории, метода и г.д.)

- наблюдать, следить за кем-, чем-либо

-to precede-

- предшествовать

 

1. This process can readily be followed with conventional methods.

2. He thinks he is being followed.

3. The discovery of the electron was followed by the investigation of its properties (mass, charge and velocity).

4. This operation has been naturally followed by writing an equation where N is substituted by the assumed number of particles.

5. The production of two hadrons has been followed by a doubling of the energy required to create a charmed particle.

6. Neutron capture by a nitrogen nucleus is sometimes followed by immediate emission of a proton.

7. Nо matter which of these approaches is followed, we shan't be able to anticipate the ultimate (окончательный) result.

8. The book is preceded by a short biography of the author.

9. An unambiguous proof was preceded by an assumption that Thomas-Fermi model cannot lake into account the covalent bond (связь) between atoms.

10. A new advance in biophysics has been preceded by an adequate explanation of some phenomena in molecular physics.

Work in pairs or groups. Discuss the points below.

1. Thomson’s model of the atom

2. Rutherford's nuclear model

3. Moseley’s model

4. Bohr Model of the Atom

 

The following conversational clichés may help you to prepare the discussion

Persuasion

Ø Don’t you think

Ø After all

Ø What you don’t seem to understand is that

Ø I’m awfully sorry to ask you… but

Ø If you do it … I’ll

Ø I don’t, but

Ø I’ll tell you what (the way)

Ø Look

Ø Why don’t we

Ø I know you can do it

Ø It’s crucial for you

Ø It’s important for you

Ø It’s necessary for you

 

Going to persuasions

Ø (Well) I guess so

Ø All right

Ø May be you’re right

Ø Oh, if you insist

Ø Look – I’ll tell you what

Ø We’ll see

 

Making suggestions

Ø I wonder/ was wondering how to attend

Ø What do you say

Ø May be you could

Ø That’s a good idea, but

Ø That’s might be OK, but

Ø That’s true, but

Ø I have an idea

Ø I think it might be a good idea,but

TEXT 3

 

Before reading the following text, work with a partner and discuss the questions below. Base your answers on your possible knowledge of the topic. Then read the text and check your guesses.

1. What is isotope?

2. How many isotopes does oxygen have?

3. How many isotopes does hydrogen have?

4. What do you know about the discovery of isotopes?

Isotopes

 

Isotopesare nuclides that have the same atomic number and are therefore the same element, but differ in the number of neutrons. Most elements have a few stable isotopes and several unstable, radioactive isotopes. For example, oxygen has three stable isotopes that can be found in nature (oxygen-16, oxygen-17, and oxygen-18) and eight radioactive isotopes. Another example is hydrogen, which has two stable -isotopes (hydrogen-1 and hydrogen-2) and a single radioactive isotope (hydrogen-3).

The isotopes of hydrogen are unique in that they are each commonly referred to by a unique name instead of the common chemical element name. Hydrogen-1 is almost always referred to as hydrogen, but the term protium is infrequently used also. Hydrogen-2 is commonly called deuterium and symbolized ²₁ D. Hydrogen-3 is commonly called tritium and symbolized ³₁ T. This text will normally use the symbology ²₁ H and ³₁ H for deuterium and tritium, respectively.

Evidence for the existence of isotopes emerged from two independent lines of research, the first being the study of radioactivity. By 1910 it had become clear that certain processes associated with radioactivity, discovered some years before by Henri Becquerel, could transform one element into another. In particular, ores of the radioactive elements uranium and thorium had been found to contain small quantities of several radioactive substances never before observed. These substances were thought to be elements and accordingly received special names. Uranium ores, for example, yielded “ionium,” and thorium ores gave “mesothorium.” Painstaking work completed soon afterward revealed, however, that ionium, once mixed with ordinary thorium, could no longer be retrieved by chemical means alone. Similarly, mesothorium was shown to be chemically indistinguishable from radium. As chemists used the criterion of chemical indistinguishability as part of the definition of an element, they were forced to conclude that ionium and mesothorium were not new elements after all, but rather new forms of old ones. Generalizing from these and other data, Frederick Soddy in 1910 observed that “elements of different atomic weights may possess identical (chemical) properties” and so belong in the same place in the periodic table. With considerable prescience, he extended the scope of his conclusion to include not only radioactive species but stable elements as well. A few years later, Soddy published a comparison of the atomic weights of the stable element lead as measured in ores rich in uranium and thorium, respectively. He expected a difference because uranium and thorium decay into different isotopes of lead. The lead from the uranium-rich ore had an average atomic weight of 206.08 compared to 207.69 for the lead from the thorium-rich ore, thus verifying Soddy's conclusion.

The unambiguous confirmation of isotopes in stable elements not associated directly with either uranium or thorium followed a few years later with the development of the mass spectrograph by Francis William Aston. His work grew out of the study of positive rays (sometimes called canal rays), first discovered in 1886 by Eugen Goldstein and soon thereafter recognized as beams of positive ions. As a student in the laboratory of J.J. Thomson, Aston had learned that the gaseous element neon produced two positive rays. The ions in the heavier ray had masses about two units, or 10 percent, greater than the ions in the lighter ray. To prove that the lighter neon had a mass very close to 20 and that the heavier ray was indeed neon and not a spurious signal of some kind, Aston had to construct an instrument that was considerably more precise than any other of the time. By 1919 he had done so and convincingly argued for the existence of neon-20 and neon-22. Information from his and other laboratories accumulated rapidly in the ensuing years and by 1935 the principal isotopes and their relative proportions were known for all but a handful of elements.