ChemistryThree Ways Tiny Bits Move
Atlas the friendly science guide stands by a table holding an ice cube, a cup of water, and a balloon, pointing at bright dots that bounce, slide, and zoom to show how tiny bits move.
- Name the three forms of matter: solid, liquid, and gas.
- Describe how tiny bits move in a solid, a liquid, and a gas.
- Sort everyday things into solid, liquid, or gas.
- Explain why a solid keeps its shape while a liquid pours.
- Explain that a gas spreads out to fill all the space it is in.
Key terms
- tiny bits
- the very small pieces that make up all matter, too small to see
- solid
- matter whose bits wiggle in place, so it keeps its shape
- liquid
- matter whose bits slide past each other, so it can pour
- gas
- matter whose bits zip around freely and fill all the space
- energy
- what makes the tiny bits move; more energy means faster movement
Bits in a Solid
In a solid, the tiny bits have low energy, so they only wiggle in place and cannot move past each other. Because the bits stay locked in their spots, a solid keeps its shape no matter where you put it. An ice cube stays an ice cube, and a wooden block stays a block. The wiggling bits hold tightly together, which is why solids feel firm and do not flow.
Bits in a Liquid
In a liquid, the tiny bits have more energy than in a solid, so they can slide past their neighbors. The bits are still close together, but they move around each other instead of staying locked in place. This sliding is why a liquid can pour and change shape. When you pour water into a cup, the bits slide and the water takes the shape of the cup, flowing to fit its new home.
Bits in a Gas
In a gas, the tiny bits have the most energy of all, so they zip around in every direction. They bounce off the walls and spread out to fill every corner of their space. That is why air fills a whole balloon instead of settling at the bottom. Because gas bits move so freely and spread so far apart, a gas has no shape of its own and fills whatever container holds it.
Worked examples
Explain why water can pour but an ice cube cannot.
- In ice, the bits only wiggle in place and stay locked together.
- In water, the bits have more energy and slide past each other.
- Sliding bits let water flow and pour, while locked bits keep ice solid.
Answer: Water pours because its bits slide past each other, while ice bits stay locked in place.
Why does air spread out to fill a whole balloon?
- Air is a gas, and gas bits have the most energy.
- The bits zip around in all directions and bounce off the walls.
- They spread out until they fill every corner of the balloon.
Answer: Air fills the whole balloon because its high-energy bits zip around and spread to every corner.
Activity
Sort each item into solid, liquid, or gas by how its tiny bits move.
Practice
Name how the tiny bits move in a solid, liquid, and gas.
Explain why a gas spreads out to fill its container.
Common mistakes to avoid
- Gas bits settle at the bottom like liquids.Gas bits keep zipping around and spread out to fill the whole space, not just the bottom.
- Tiny bits stop moving in a solid.The bits in a solid still wiggle in place; they just cannot move past each other.
Check your understanding
In a liquid, how do the tiny bits move?
Which one is a solid that keeps its shape?
What do the tiny bits in a gas do inside a balloon?
Recap
Matter comes in three forms based on how its tiny bits move: solid bits wiggle in place and keep their shape, liquid bits slide past each other and pour, and gas bits zip around freely and spread out to fill all the space.
Reflect
Which kind of moving bits is the most fun to imagine, and why?