1. Put 6 questions to the text and answer them:

1. What is the general configuration of an atom?

2. Translate the following sentences in to Russian:

Liquids are characterized by possessing a definite volume but no fixed form; they take the shape of the vessel containing them, except when in minute quantities, as drops, they assume a form more or less spherical. According to the kinetic theory, the mol­ecules of a liquid are packed close together and attract one another; the attraction is not great enough, however, to prevent their motion. There is not much free space between the molecules, because liquids are very incompressible - a great pressure has little effect in decreasing the volume of a liquid.

Solids possess a definite form. According to the kinetic theory the molecules are closely packed, and the attraction between them is great enough to prevent free motion. It is possible in a solid, therefore, to have a definite arrangement of the molecules which

remains fixed; this is seen in the fact that many solids assume definite forms which are characteristic. For example, when sodium chloride separates from a solution in water, it appears as cubes. Other substances appear in other geometric forms.

Substances which are composed of identical molecules are pure substances (pure water, pure oxygen and etc.). Substances which are composed of the molecules of dif­ferent pure substances are mixtures and compound substances.

By the atomic-molecular theory, chemical reactions represent a rearrangement of atoms into new molecules. This rearrangement is accompanied by the liberation of heat, gas, radiation or by the absorption, for entrance, the same heat.

The rate of chemical reaction is measured by the change in the concentration of one of the substances or of one of the products, per unit of time. The most important factors which influence the rate of chemical reactions are: the concentration of the substance, the temperature and the presence of a catalyst.

1. Translate the following text and he ready to discuses properties of elements: Chemical properties of elements

Vanderwaals radius

Even when two atoms that are near one another will not bind, they will still attract one another. This phenomenon is known as the Vanderwaals interaction. The Vander­waals forces cause a force between the two atoms. This force becomes stronger, as the atoms come closer together. However, when the two atoms draw too near each other a rejecting force will take action, as a consequence of the exceeding rejection between the negatively charged electrons of both atoms. As a result, a certain distance will develop between the two atoms, which is commonly known as the Vanderwaals radius. Through comparison of Vanderwaals radiuses of several different pairs of atoms, we have devel­oped a system of Vanderwaals radiuses, through which we can predict the Vanderwaals radius between two atoms, through addition.

Ionic radius

The radius that an ion has in an ionic crystal, where the ions are packed together to a point where their outermost electronic orbitals are in contact with each other. An orbital is the area around an atom where, according to orbital theory, the probability of finding an electron is the greatest.