Primary 4 Classes
|Matter||Solid, Liquid, Gas
– Matter is anything that
a) has mass; and
b) occupies space (volume)
– Properties of Solid, Liquid and Gas
a) Definite/No definite shape
b) Definite/No definite volume
c) Can/Cannot be compressed
|Light Energy|| – Properties of light
– Light and materials
|Heat Energy||– Sources of heat-
– Conductors and Insulators
– Movement of heat
Question 1: Which pot, A or B, needs a longer time to boil the soup to 120oC? Explain.
Although the temperature of both pots is the same, pot B needs more heat to bring the pot of soup to the same temperature as that of pot A. Hence, pot B needs a longer time to boil to 120oC.
Primary 4 - Topic :Matter
What is Matter?
- Matter is anything that has mass and occupy space.
- Things that do not have mass or occupy space are not matter.
Examples of non-matter are shadow, heat, light, lightning, thunder, music, electricity, rainbow.
1. Matter has mass
- Matter has mass. Mass is the amount of matter or amount of substance in a body or object.
- Mass is measured in grams (g) or kilograms (kg).
- Mass is not the same as weight.
2. Matter occupies space
- The amount of space that an object occupies is called its volume.
- In the diagram below, air occupies space in the conical flask, preventing the water from flowing into it.
Three States Of Matter
- The atoms in a solid are packed closely together in a regular pattern. Thus, a solid has a fixed or definite shape.
- The shape of a solid can be changed only if a force is applied to it.
- It only changes its shape if we bend, dent, break or stretch it.
- When we said the solid cannot be compressed, it means that the volume of the solid cannot be changed or compressed to occupy a smaller space
- The atoms in a liquid are not held in a regular pattern and are not packed as closely as those in solid. Thus, a liquid has no definite shape. It takes the shape of the container. The volume of a liquid remains the same when it is poured from one container to another.
- There is still very little space between atoms, therefore, they can not be pushed together to occupy a smaller space. Thus, a liquid cannot be compressed and has a definite volume.
- A syringe contains water. The plunger cannot be pushed in any further because water cannot be compressed.
- The atoms are widely spaced in an irregular manner. As a result, they have indefinite shape and indefinite volume. Hence, a gas takes the shape of its container.
- The large spaces between the atoms enable the particles to be forced together to occupy a smaller space.This means that gas can be compressed.
- The volume of a gas can be changed– it can be either compressed to occupy a smaller space or expanded to occupy a bigger space.
- The table tennis ball became smaller and took up less space when it was squeezed. The air inside was compressed.
A summary table:
CAN IT BE COMPRESSED?
|Solid (cm3)||Definite shape||Definite volume||Cannot be compressed|
|Liquid (ml)||No definite shape||Definite volume||Cannot be compressed|
|Gas (cm3)||No definite shape||No definite volume||Can be compressed|
|1)||Wrong concept: Plasticine is not a solid as it has no definite shape.
Right concept: A solid can only change its shape if a force acts on it.
Plasticine does not change its shape when it is not moulded.
|2)||Wrong concept: Substances like salt and sugar are not solid because they take the shape of the container.
Right concept: Each grain of sand or sugar is a solid. It is small so many that it can fit into a container.
|3)||Wrong concept: Weight is the same as mass.
Right concept: Mass is the amount of matter in a body. It does not change.
Weight is due to the gravitational force applied on an object and can change.
|4)||Wrong concept: Gases do not have mass or weight.
Right concept: Gases are matter and thus have mass and weight.