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“Matter”

I

Until the beginning of the seventeenth century mankind had little understanding of the structure of the material world. Man believed that stones were stones, tire was tire, water was simply water.

The ancient Greeks studied the structure of matter and noted that it is possible to divide and subdivide a stone until the particles become like the powder, which they thought was the limit of divisibility. They called these smallest particles atoms. The word atom means “indivisible”. It came from the Greek.

But it was the beginning of the nineteenth century that the scientists first established experimentally the atomic theory of the structure of the matter. At the end of the nineteenth century scientists achieved a great quantity of information on the atomic structure of matter and the general nature of the atom.

The word molecule means “a little structure”. It is a combination of two or more atoms. If the atoms are of different leads we call the combination a compound, and the molecule is the smallest possible unit of the compound. It is impossible to subdivide the molecule and not to destroy the compound.

Molecules differ greatly in size and weight. So most of the chemical elements are different in chemical and physical properties from the properties of other elements. In all substances the atoms and molecules are in a state of rapid motion.

II

When we think of the substance which we call water, we commonly think of it as a liquid. It does not mean, however, that this is the only possible state in which water can exist. The liquid state is the normal state for the substance which we call water, but water can exist also as a gas and as a solid. In the gaseous state it changes to steam or water vapour. And in the solid state it becomes ice. And there is an equal number of molecules of the same kind in a pound of water as in pound osf steam or in a pound of ice. Many substances can and do at various times exist in more than one of these three possible states.

Why, then, do the various states exist and why do they differ so greatly? It depends on the fast that the molecules move differently in the three states. In gases we find that the gas molecules are free to move and they are far apart. And a body of gas has no definite volume or shape.

The molecules of a liquid are less free to move than the gas molecules but they have an attractive force. Though, a liquid has no definite shape but volume.

A solid has both volume and shape. The molecules of a solid have a great attraction for each other but they are also in motion and they can move only a small amount because the atoms are very close together. The closer the molecules are together, the less heavier is the solid.

The three states of states of matter – solid, liquid and gaseous – are very close to each other and more heat or less heat will change the substance from one state to the other.

III

So, as we know, the scientists call tiny units atoms. They are building blocks all of matter.

Some atoms are found alone. Some atoms combine with other ones. Two or more atoms joined together in certain way form molecules. Some molecules can be made of two or more of the same kind of atoms. Other molecules are made of different kind of atoms.

Matter made of all the same kind of atoms is called an element. There are over 100 different kinds of atoms. Elements can be solids, liquids or gases. There are metallic elements and nonmetallic elements.

Most matter around us is not made up of single elements. Water and sugar, for example, are not elements. They are compounds. Compounds are matter made up of more than one kind of element.

Got all matter is the same. Matter has different properties. The properties of matter are what we can sense or measure.

Cotom, mass, smell, taste, and hardness are some properties of matter. Some of these properties can be sensed and other can be measured. Mass is the amount of matter in an object. Mass is measured in grams or kilograms. Weight is also a property of matter is measured in Newtons. Matter takes up space. The amount of space matter takes up is called volume. It is also a property of matter. Volume is measured in cubic meters and centimeters.

Throughout the history of humans on our planet, the properties of matter have been utilized to make life easier and more enjoyable.

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