Properties of Matter

The entire universe is composed of two basic components

1.0Matter

Matter, the “stuff” of which the physical universe is composed. 

Matter comes in a great variety of forms: the stars, the air that you are breathing, the gasoline (petrol) that you put in your car, the chair on which you are sitting, the cheese in the sandwich you may have had for breakfast, the tissues in your brain that enable you to read and comprehend this sentence, and so on.

All these examples of matter resemble in some ways and differ in others, but the most                common thing among all is that they have mass and occupy space. Thus, we can say, Matter is anything that has mass and occupies space and can be perceived by our senses.

2.0Energy 

Things that exist around us but do not have any mass or occupy space are not considered as matter. Energy is the capacity to do work.

Some different forms of energy are sound energy, light energy, heat energy, chemical   energy etc.

Moreover, the perception of joy, love, hate, thought, cold, pain are also not considered as matters.

3.0Properties of Matter

When you come into a new situation or have to make any kind of decision, what do you usually do first? Most people would make some observations. Observing involves seeing, hearing, tasting, touching, and smelling.

The characteristics that we use to identify matter and distinguish them from one  another are called properties.

We group these properties into two broad categories

4.0Physical Properties

Physical properties of matter are usually those that we can  observe with our senses. A substance's physical property allows us to identify the substance without causing a change in the composition of the substance.

Examples: Colour, shape, size, smell, hardness, texture, density etc.

If you toss your coin in a fountain, it will sink. This is because your coin is more dense than the water in the fountain. Your coin may be a little wet, but it is still composed of the same material as it was tossed before you tossed it in the fountain. Thus density is an example of a physical property.

5.0Chemical Properties

Any characteristic that gives a sample of matter the   ability/inability to undergo a change that alters its composition.

Examples: Some metals react with water, paper's ability to burn.

Iron nail is made of iron. Iron has characterised Greyish-black colour.  Over time the iron reacted with the oxygen in the air and water to change its colour reddish brown.     

6.0States of Matter

To try to understand the nature of matter, we classify it in various ways.

Observing physical properties will help you interpret the world around you and classify things into solids, liquids and gases.

For example, wood, bone, and steel share certain characteristics. These things are all rigid; they have definite shapes that are difficult to change.

On the other hand, water and gasoline, for example, take the shape of any container into which they are poured. Even so, 1 L of water has a volume of 1 L whether it is in a bottle or a beaker.

In contrast, air takes the shape of its container and fills any container uniformly. The substances we have just described illustrate the three states of matter: solid, liquid, and gas.

Example: Water can exist in all the three states: ice as solid, water as liquid and steam as vapour. The three states of water have distinctly different properties. If a pond freezes in the winter, you can walk across it. Solid water can support your weight. Conversely, you would never try to walk across the same pond in summertime. 

The state of a given sample of matter depends on the strength of the forces among the particles contained in the matter; the stronger these forces, the more rigid the matter. We will discuss this in more detail in the next section.

7.0Differences Between The Three States of Matter

Matter is made up of very small particles called molecules. These particles are so small that you cannot see them even under any ordinary microscope. Molecules attract each other with a force. This force is called intermolecular force.

There is also some space between the molecules, called intermolecular space. The greater the intermolecular force, the closer will be the molecules to each other. And the weaker the intermolecular force, the farther apart will be the molecules.

Swimming is possible because of spaces present between water molecules

8.0Change of State of Matter

As you know, if you heat or cool water up to a certain temperature, its state changes. In general, a solid changes into a liquid, and a liquid into a gas on being heated enough. The opposite change takes place when a substance is cooled sufficiently.

When a substance melts or boils, it doesn't change into a different substance. Water is still water, whether it is a solid, a liquid, or a gas. A change of state, such as from a solid to a liquid, is a physical change. During a physical change, the appearance of a substance changes but its properties stay the same.

(1) Melting : When heated, the molecules in a solid gain energy and vibrate more vigorously. When heated sufficiently, the molecules gain enough energy to overcome intermolecular attraction and move far apart. Hence a solid changes into a liquid.

The change in state from solid to liquid is known as melting.

The temperature at which a solid melts is called the melting point of the solid.

(2) Boiling : As a liquid is heated, the molecules gain energy and move more vigorously. Some molecules gain enough energy to move away very far from the other molecules, to form a gas.

Change in three states of matter

The change in state from liquid to gaseous is known as vaporisation or boiling.

A liquid evaporates faster as the temperature is raised. When the temperature reaches a certain point, the liquid begins to boil. The temperature at which a liquid boils is known as its boiling point.

A liquid evaporates very fast at its boiling point.

(3) Condensation : When cooled, the molecules of a gas lose energy and slow down. The intermolecular space decreases and intermolecular force increases. So the gas changes into a liquid. 

The change in state from gaseous to liquid is called condensation or liquefaction. 

(4) Freezing : On further cooling, the molecules become even less energetic and move still closer. The intermolecular force increases and the liquid becomes a solid.

The change in state from liquid to solid is called freezing.

(5) Sublimation : Some solids vaporise without melting. Such a conversion, i.e., change in state, is known as sublimation. When cooled, the vapours of such substances directly solidify. The solid thus obtained is called a sublimate.

Sublimation

Ammonium chloride, naphthalene (the chemical substance in mothballs) and iodine are common substances that sublime.

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