Matter and Materials Chapter Notes | Science Olympiad Class 4 PDF Download

Matter and Its Forms

Everything in the universe, including solids, liquids, and gases, is composed of matter. Matter possesses mass and occupies space, allowing us to measure its weight. When we create objects like wooden or plastic chairs, we attribute the materials used, such as wood or plastic, to the substances involved.

Properties of Solids

In scientific terms, the concept of "property" refers to the distinguishing characteristics of a particular form of matter. Solids, for instance, maintain their shape even when moved to a different location. This attribute, known as shape retention, is a property unique to solids. Let's explore further properties of solids.
Solids have a fixed shape and occupy a defined volume, as we have discovered. Now, let's shift our attention to liquids.

Properties of Liquids

Liquids are abundant in our surroundings, and we encounter them in our daily lives. Common examples include water, paraffin, baby oil, fruit juice, petrol, and methylated spirits. What are the shared properties of liquids?
Scientists employ experimentation to address their queries and expand their knowledge. Through such investigations, we have determined that liquids:

• Can flow,
• Lack a fixed shape,
• Assume the shape of their containers.

These characteristics differentiate liquids from solids. Remember, you cannot pour a solid!

Properties of Gases

Gases present a greater challenge in comprehension since they are usually invisible to the naked eye. Nevertheless, we can observe their utilization and the containers in which they are stored.
Can you think of any gases? How about the gas used for cooking on a stove? Have you noticed the gas emanating from a car's exhaust? In hospitals, oxygen gas cylinders aid patients with breathing difficulties. Oxygen gas is also present in the air we inhale, while exhaled air contains an increased concentration of carbon dioxide gas.

Similar to liquids, gases:

• Can flow,
• Lack a fixed shape,
• Assume the shape of their containers.

These properties distinguish gases from solids, which possess a fixed shape and cannot be poured.

Changes of State

We are aware that matter can exist in solid, liquid, or gas states. Let's use water as an example to illustrate state changes.

Melting

Consider Mashadu's experience with ice lollies. Initially, the frozen lollies were cold. However, when exposed to sunlight, they began to warm up, causing a change in state from solid to liquid. This transition is referred to as melting.

Solidifying

When Mashadu and the Thunderbolt Kids purchased new ice lollies, these frozen treats were made from a liquid. The liquid was poured into ice lolly molds and subsequently cooled. As heat dissipated, the liquid solidified, transforming into a solid state.

Evaporation

Evaporation occurs when heat is applied to a liquid, causing it to change from the liquid to the gaseous state.

Condensation

If you observe the steam released from a kettle, you'll notice that it is initially invisible but quickly cools down, forming tiny visible droplets in the air. These droplets combine to create the clouds we see. When these condensed droplets come into contact with a mirror, they cool further, forming larger droplets. This transformation from gas to liquid is known as condensation and occurs when heat is removed.
When a glass of cold water is left on a table, you may notice small droplets forming on the outside. This is due to water vapor in the air cooling when near the cold glass. The water vapor condenses, transitioning from a gaseous to a liquid state, resulting in the formation of the observable tiny droplets.

The Water Cycle

The Earth, often referred to as the blue planet, contains a significant amount of water covering its surface, with land comprising a smaller portion.
Did you know that the amount of water on Earth remains relatively constant, similar to the time when dinosaurs roamed the planet? This is possible due to the continuous process of invisible water vapor cooling and condensing into liquid droplets. Conversely, water evaporates, transforming into a gas called water vapor. This perpetual transformation of water from a liquid to a gas and back again is known as the water cycle, ensuring the Earth's water supply remains stable.