Characteristics of Particles of Matter

Even if a solid object looks completely solid and unbroken to our eyes, at the microscopic level, there are empty spaces between its particles.

Proof Activity: When you dissolve a spoon of sugar in a glass of water, the water level does not rise. This happens because the tiny sugar particles break apart and hide in the empty spaces existing between the water particles.

Particles are never completely still; they are always vibrating, rotating, or moving around. Because they move, they possess Kinetic Energy.

• In Solids: They vibrate tightly in their fixed positions.
• In Liquids: They slide past one another.
• In Gases: They fly around rapidly in all directions.

Temperature Effect: If you heat a substance, you give it thermal energy. This turns into kinetic energy, making the particles move faster. Proof Activity: The smell of hot cooked food reaches you from meters away because the hot aroma gas particles are moving very fast and mixing (diffusing) with the air particles rapidly.

There is an invisible force of attraction holding the particles together. The strength of this force determines the state of the matter.

• Maximum attraction: In solids (e.g., an iron nail is hard to break because the particles hold on to each other very tightly).
• Medium attraction: In liquids (water flows because the attraction is weak enough to let particles slide).
• Minimum attraction: In gases (oxygen gas fills a whole room because the particles barely attract each other at all).