Lesson 1 :

The characteristics of matter

Lesson 3:

Matter construction

Lesson 4:

Atomic structure

1. Matter is everything that has mass & volume.

1. Air, Water are example of matter.

2. Different kinds of matter differ in their characteristics.

3. Water & vinegar have different tastes.

4. Colour, taste & smell help us to distinguish different substances.

2. Density

Activity 1:

Put a nail, the piece of wood, some oil & an ice cube in a beaker of water.

• Observation :

1. The nail sinks in the water.

2. The ice , the piece of wood & oil float on the surface of water.

• Conclusion:

1. The nail is denser than water, therefore it sinks.

2. The ice , candle & oil are less dense than water & therefore they float.

Density is the mass of a unit volume (1 cm³)

1 cm³

Iron

Mass = 7.87g

1 cm³

Water

Mass = 1g

1 cm³

Oil

Mass = 0.82g

D ensity is calculated by the rule

Density =

	Mass	Volume	Density
Unit	gm	cm3	g/ cm3

A solved example:

An object’s mass is measured in the lab. & found to be 50g.

The volume was also measured & found to be 25 cm³.

Can you find through calculations if this object floats or sinks in water.

S olution:

D ensity =

= = 2 g/ cm³

The density of this object is bigger than water 1 g/ Cm³ therefore it sinks.

E xplain why:

1. Balloons filled with helium rise upwards. That’s because the density of helium is less than that of air.

2. Burning oil & flaming petroleum oil aren’t extinguished with water.

The density of oil is lower than water, therefore oil floats on top of water & keeps burning.

3. Melting point:

1. Melting is the change of the state of an object from solid to liquid.

2. Melting needs heating to occur.

3. The temperature at which melting of a substance begins is called melting point.

4. Metals such as iron, copper & aluminium have high melting points.

5. Ice, wax & butter have low melting points.

6. Metals have high melting points.

Explain why:

1. Metals are molten to make machines from them.

B ec. Molten metals are easily shaped or mixed into alloys.

2. Cooking pots are made of stainless steel alloy.

Bec. Both aluminum & stainless steel are good conductor of heat and

have high melting points.Stainless steel also doesn’t rust when water is heated inside it.

An alloy is a mixture of 2 metals or more, metals are mixed to improve their characteristics.

E xamples are :

1. Gold & copper alloy used in making jewellery.

2. N ickel chrome alloy used in making the heating coils of electric heaters & boilers.

4. The boiling point is the temperature at which a substance begins to change from the liquid into the gaseous state.

Different substances have different boiling points.

5. Electric conduction

	Good electric conductors	Bad electric conductors
Definition	They allow electricity to pass through them.	They don’t allow electricity to pass through them.
Examples	M etals such as copper & silver. Some acid, alkali or salt solutions.	N on – metals such as sulphur & phosphorus. Sugar solution H ydrogen chloride solution in benzene. wood & plastic.
Uses	Electric cables are made of copper Electric screwdrivers are made of steel.	H andles of electric screw drivers are made of wood or plastic.