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II. Read and translate the text.

In order to understand how electric charge moves from one atom to another, we need to know something about atoms. Everything in the universe is made of atoms every star, every tree, every animal. The human body is made of atoms. Air and water are, too. Atoms are the building blocks of the universe. Atoms are so small that millions of them would fit on the head of a pin.

Atoms are made of even smaller particles. The center of an atom is called the nucleus. It is made of particles called protons and neutrons. The protons and neutrons are very small, but electrons are much, much smaller. Electrons spin around the nucleus in shells a great distance from the nucleus and are held in their shells by an electrical force.

The protons and electrons of an atom are attracted to each other. They both carry an electrical charge. An electrical charge is a force within the particle. Protons have a positive charge (+) and electrons have a negative charge (-). The positive charge of the protons is equal to the negative charge of the electrons. Opposite charges attract each other. When an atom is in balance, it has an equal number of protons and electrons. The neutrons carry no charge and their number can vary.

The number of protons in an atom determines the kind of atom, or element, it is. An element is a substance in which all of the atoms are identical (the Periodic Table shows all the known elements). Every atom of hydrogen, for example, has one proton and one electron, with no neutrons. Every atom of carbon has six protons, six electrons, and six neutrons. The number of protons determines which element it is.

Vocabulary

III. Remember these words:

particle, shell, empty, force, both, equal, to determine, hydrogen, carbon, to push, to apply.

IV. Translate the following sentences, paying attention to the words in bold type.

1. If the water is heated in a closed container, the temperature and the pressure both rise.

2. Both Lomonosov and his friend Rihman worked at atmospheric electricity. Both of them made experiments on that subject.

3. Take botha small cup of boiling water and a large container also full of boiling water; you will find that both of them have the same temperature.

Grammar

V. Find suitable attributes in (a) for the nouns in (b).

a) 1.famous; 2.boiling; 3.glass; 4.cold; 5.scientific; 6.electrical; 7.mercury.

b) 1.water; 2.problem; 3.thermometer; 4.device; bulb; 6.scientist; 7.point.


Date: 2015-12-11; view: 1041


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