Primary 4 Classes

Topics

Big Ideas

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
– Shadows
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

Solid
  • 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

Liquid
  • 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.
Gas
  • 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:

SHAPE

VOLUME

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

Misconception

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.