General Remarks (текст с послетекстовыми заданиями для изучения профессионального модуля)

General Remarks

Atoms are the building bricks of all the numerous things, both living and non-living that exist on the earth.

Atoms are made up of three particles: the electron, the proton and the neutron.

Let us start with the electron. We all use electrons. When we switch on the electric light we make the electrons flow along the wires. The stream of electrons is the electric current.

Each electron is, in fact, a very small negative electrical charge, and it is the smallest electrical charge known. The electron is almost weightless.

The next particle to talk about is proton. This, again, is a very small particle. Its diameter is about 0,00000000000005 of an inch. The proton carries a single positive electrical charge, and the charge on a proton exactly balances the negative electrical charge of an electron.

The last particle to mention is the neutron. This has the same size and weight as the proton, but does not carry any electrical charge either positive or negative. When we examine any atom we find that it contains the same number of electrons and protons.

Now let us have a look at the individual types of atoms.

The outer layer of the atom containing the electrons. In the centre is the nucleus. Here the protons and the neutrons are found

The simplest atom has just one proton in its nucleus. In motion around the nucleus there is one electron. All such atoms are called hydrogen atoms. The next simplest atom is known as a helium atom, it has two protons in its nucleus and two electrons in motion around it. And the next - lithium - has three protons and three electrons. Each type of atom has a name. Three (hydrogen, helium and lithium) are given above. Others are oxygen (6 protons), iron (26 protons), mercury (80 protons) and uranium (92 protons).

There are about 100 different types of atoms. They differ from each other in the number of electrons, protons and neutrons which they contain.

An atom consists of two zones - a centre, known as the nucleus, containing both protons and neutrons, and the outer layer, containing the electrons.

The nucleus of an atom may be compared to a magnet. Two magnets attract one another if we bring them close together, a north pole and a south pole.

Here, in the atom the attraction of the opposite charges is similar to that between a south and a north pole of a magnet.

The electrons are trapped inside a zone around the nucleus, and a strong attractive force holds them together in the zone.

But electrons unlike iron objects do not attach themselves to the nucleus. Here the similarity between the behaviour of a magnet and that of the nucleus ends.

The nucleus of an atom can also attract electrons from other atoms. That is one of the ways in which atoms are joined together.

A very small part of a polythene chain

Polythene is made from two elements - carbon and hydrogen. Carbon is a black solid, hydrogen is a gas. Polythene consists of long chains of carbon atoms. Each chain contains about 1000 carbon atoms. The carbon atoms in the polythene chains are held together by each carbon atom attracting an electron of each neighbouring atom.

So any two carbon atoms are held together by two electrons - one from each atom. These electrons are held in place by the attraction, of both nuclei, of the carbon atoms.

Vocabulary:

1. to talk about - о которой следует говорить

2. an inch - дюйм (2,5 см)

3. This has the same size and weight - Он обладает такими же размерами и весом

4. In motion around the nucleus - Вокруг ядра движется

5. known as - известного как

6. is similar to that between a south and a north pole - подобно притяжению между северным и южным полюсами

7. and that of the nucleus - и поведением ядра

8. particle - частица

9. wire - провод

10. stream - поток

11. current - ток

12. charge - заряд

13. balance - уравновешивать

14. hydrogen - водород

15. helium - гелий

16. lithium - литий

17. oxygen - кислород

18. iron - железо

19. mercury - ртуть

20. outer layer - внешний слой (орбита)

21. to attach - прикреплять

22. polythene - полиэтилен

23. carbon - углерод

24. solid - твердое вещество

25. nuclei - ядер (мн. ч., Р. п.)