Lesson 2

I. Memorize the following words:

Whether - будь-то, ли sign – знак

Solid – твердое тело the latter – последний (из двух)

Liquid – жидкость, жидкий enough – достаточно, достаточный

To call – звать to reveal – обнаруживать

In one’s turn – в свою очередь wavelength – длина волны

Visible - видимый To get (got got) – получать, доставать

To be made up of – состоять из to depend on (upon, of) – зависеть от

To be composed of – состоять из to vary – менять(ся), изменять(ся)

To consist of – состоять из starch - крахмал

To remember – напоминать i.e.(that is) – то есть

To contain –содержать to break down – дробить, делить, толочь

To consider – считать, полагать former – прежний, первый (из двух)

To rotate (to revolve) – вращать in turn - по очереди, один за другим

Single – единственный Amount – количество, величина

Structure of matter

All matter whether solid, liquid or gas is made up of very small particles called molecules. Molecules in their turn are made up of atoms which are much smaller particles. A molecule of any substance is the smallest bit of this substance. If you break it down any further you will not get the former given substance but the individual atoms of which the molecule is composed.

Scientists think that the structure of the atom resembles a miniature solar system i. e. the atom contains a central part, or nucleus. The nucleus of the simplest atom, the hydrogen atom, consists of a particle of positive electricity called a proton. Around the proton and at a great distance from it (considering the size of the particle involved) a single electron which is a particle of negative electricity rotates.

The amount of electricity of the proton is as large as that of the electron, but they have opposite signs. However, the mass of the hydrogen atom is practically defined only by the proton mass since the latter is 1,840 times greater than that of the electron. The atom diameter is many times greater than that of the proton. The proton is heavier than the electron. So the proton is a much more concentrated and compact particle.

Atoms, protons and electrons are all so small that the most powerful microscope in the world is not good enough to reveal them.

The largest molecule is much smaller than the smallest wavelength of visible light. All the molecules vary in size depending upon the number and size of all the atoms composing them. They vary from simple ones consisting of two atoms such as the hydrogen molecule, to the most complex ones, like those of starch, some of which contain as many as 2,500 atoms.

The hydrogen molecule diameter is the smallest. The size of atoms varies depending upon the number of the electrons revolving around the nucleus. The hydrogen atom, the simplest one, is naturally the smallest. The uranium atom, the most complex one, is the largest.

Molecules and atoms are in constant motion. If the temperature is the same lighter molecules move at greater speeds than heavier ones. The heavier the molecule, the slower is its speed.