Lomonosov exclude antimony and mercury from the list of metals?
7) What was the first scientific definition of metals given by Lomonosov?
8) How are metals defined in engineering?
9) What is an alloy?
4. Найдите в тексте предложения, соответствующие данным:
1) В течение многих столетий металлы служили человеку, помогая ему покорять природу, создавать полезные машины и механизмы.
2) Металлы нашли широкое применение, потому что они обладают свойствами, которые сделали их такими полезными.
3) Ломоносов исключил сурьму и ртуть из списка металлов из-за их плохой ковкости.
4) Не только чистые металлы обладают этими свойствами, но также и соединения, состоящие из многих элементов.
UNIT 2
Vocabulary
to base on – основывать на
composition – состав
ferrous – черный
non-ferrous – цветной
alloy – легировать, сплавлять; сплав
alloying element – легирующий элемент
simple – простой
pure – чистый
purity – чистота
impurity – примесь
cast iron – чугун
malleable – ковкий
steel – сталь
carbon steel – углеродистая сталь
alloy steel – легированная сталь
stainless steel – нержавеющая сталь
light – легкий
heavy – тяжелый
alkali metal – щелочной металл
alkali earth metal – щелочно-земельный металл
rare – редкий
precious – драгоценный металл, благородный металл
refractory – тугоплавкий
to exhibit – проявлять свойства
high melting point metal – металл с высокой точкой плавления
low melting point metal – металл с низкой точкой плавления
resistance – устойчивость
corrosion resistant – коррозионно-стойкий
wear resistant – износостойкий
to vary – варьироваться, различаться
hard (hardness) – твердый (твердость)
soft (softness) – мягкий (мягкость)
industrial application – промышленное применение
semimetal – полуметалл
semiconductor – полупроводник
arsenic – мышьяк
Подберите к английским словам их русские эквиваленты:
1) composition а) чистый
2) impurity б) ковкий
3) malleable в) драгоценный
4) to exhibit г) чугун
5) semiconductor д) мышьяк
6) resistance е) редкий
7) precious ж) простой
8) arsenic з) устойчивость
9) cast iron и) примесь
10) rare к) полупроводник
11) pure л) проявлять свойства
12) simple м) состав
Подберите пары слов, имеющих противоположные значения:
1) ferrous а) high melting point metal
2) purity б) heavy
3) light в) alloy
4) low melting point metal г) soft
5) hard д) impurity
6) simple metal е) non-ferrous
7) inexpensive ж) true metal
8) semimetal з) expensive
CLASSIFICATION of METALS
There are some classifications of metals based on their chemical purity, physical and chemical properties and composition, their industrial application, etc.
According to the chemical puritywe may divide all metals into 2 large groups: 1) simple metals which are more or less pure chemical elements, 2) alloys which are materials consisting of a simple metal combined with some other elements.
In modern industry we usually divide metals into 2 main groups according to their chemical composition: 1) ferrous metals, 2) non-ferrous metals.
Metals consisting of iron combined with some other elements are known as ferrous metals. All the other metals are called non-ferrous metals. Ferrous metals and alloys include a great variety of important products which can be grouped into iron (cast iron), carbon steel, stainless steel, alloy steel and other types of steel.
The most important ferrous metal is cast iron which is some form of alloy with carbon and other elements. Cast iron finds greater use than any other metal. We may classify all cast irons into 3 groups: grey cast iron, white cast iron and malleable cast iron.
Non-ferrous metals may be subdivided into 2 groups:
1) the so-called group of rare metals (bismuth, tungsten, molybdenum, cobalt, etc)
2) the so-called group of precious metals which include silver, gold, platinum, palladium, indium.
In respect to their density metals may be divided into light and heavy ones. Metals having a density less than four are called light metals. All other having a density over 4 are known as heavy metals. The alkali metals and the alkali earth metals also belong to light metals. Light metals are aluminium, magnesium, titanium. Heavy metals include such metals for example as lead, tin, silver, copper, nickel, zinc. The lightest metal is lithium (D - 0,534) and the heaviest is osmium (D - 22,48).
Metals may also be classified according to their melting point. Metals which exhibit high melting point above 3000 (1650 C) are often called refractory metals. These metals also exhibit great corrosion and wear resistance and are very difficult to produce. The low melting point metals are rubidium, cesium which melt just above room temperature and mercury which melts at -38,8 C.
We may also classify hard and soft metals. For example, potassium is so soft that it can be molded like wax, chromium is so hard that it can even cut glass.
Many elements are classed as semimetals (arsenic, antimony, etc) because they possess much poorer conductivity than true metals and may be classed as the semiconductors.
Ответьте на следующие вопросы к тексту:
1) Into what groups may we divide metals according to their chemical purity?
2) What is a simple metal?
3) What is an alloy? What does it consist of?
4) Into what groups do we usually divide metals according to their chemical composition?
5) How will you call metals consisting of iron combined with some other elements?
6) Into what groups may we divide ferrous metals?
7) What is the most important ferrous metal?
8) How are cast irons classified?
9) What kind of steels do you know?
10) What non-ferrous metals do you know?
11) How are metals divided in respect to their density?
12) What is the density of a light metal?
13) What is the density of a heavy metal?
14) What metals do alkali and alkali earth metals belong to?
15) How can metals be classified according to their melting point?
16) What metals and alloys are called refractory? Are they difficult
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