Engineering MOSAIC. Мантатова С.С - 30 стр.

UNIT XXIV                                                                     Controversies have often arisen as to the priority of a discovery,
Thallium                                                                and thallium was no exception. Professor A. Lamy, working
Before you start                                                        independently of W. Crookes, observed the same spectrum line in the
1. What do you think will happen when the world runs out of metals?     residues from another sulfuric acid plant and claimed credit for its
Vocabulary                                                              discovery. W. Crookes was, probably, prior to A. Lamy in discovery
2. Match the words from the text with the meanings (1-7) below:         and preparation by only a few months.
a. bud               1. something that remains                                W. Crookes' assumption that thallium belonged to the sulphur
b. twig              2. to say something is true                        family was soon disproved as the physical and chemical properties
c. residue            3. a small structure that contains flowers or     were investigated. Studies revealed that the element was closely
                      leaves                                            associated with lead, mercury, potassium and aluminum. Mendeleyev
d. to resemble       4. a glow of reflected light                       when publishing his atomic table placed it in Group III under indium
e. tinge             5. to be similar to                                between mercury and lead; and this has been its accepted place ever
f. luster            6. a slight trace of colour                        since.
g. to claim          7. a small shoot                                         Thallium is found in potash minerals, which have no
                                                                        commercial significance at present. Today the metal is recovered
Reading                                                                 mainly as a by-product from the roasting of pyrite ores in the
3. Read the text and find answers to the questions below:               production of sulfuric acid and from the smelting of lead and zinc.
     1. What was the year of thallium discovery?                              Metallic thallium when freshly cut has a metallic luster, which
     2. Who named the element “thallium” and why?                       upon exposure to air dulls to a bluish grey tinge resembling lead in
     3. What group of chemical elements is thallium associated          appearance. As a matter of fact, the properties of thallium are very
         with?                                                          similar to those of lead.
     4. Where is thallium placed in the Mendeleyev table?                     Investigations of the systems of thallium and other elements
     5. What colour has this element when it is exposed to air?         show that thallium readily alloys with many other elements, the
                                                                        exceptions are copper, zinc, aluminum, nickel and selenium.
                             Thallium                                   Speaking
      Thallium made its public debut in 1862 at the International       4. Arrange the following sentences according to the logic of the text:
Exhibition in London. The year before W. Crookes searching by               1. It is often discussed who is the first to discover a new
spectrography for tellurium in the residues of a German sulfuric acid           element, and thallium was no exception.
plant noted an unaccountable green line in the spectrum. He                 2. Thallium didn’t belong to the sulphur family because of the
concluded that this line represented a new element.                             physical and chemical properties.
      With a poetic touch he compared the colour of the spectrum            3. Professor A. Lamy was the first to discover a new element.
line to the bright green tint of new vegetation and named the element       4. Lead and thallium stand near each other in the atomic table.
thallium from the Latin thallus – “a budding twig”. He was                  5. Investigations show that thallium doesn’t alloy with zinc.
successful in obtaining a small quantity in metallic form for display
at the 1862 International Exhibition in London.                         5. Work with a partner. Persuade your partner that is it difficult to be
                                                                          a discoverer of a new metal using the information from the text.