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See how the way atoms move determines if something is a solid, liquid, or gas.
Have you ever wondered why a solid ice cube can turn into a runny liquid and then disappear into the air as an invisible gas? It’s all because of a secret dance happening at the tiniest level imaginable!
Imagine atoms are like students sitting in their desks at school. In a solid, atoms are packed very tightly together in a neat, organized pattern. They are stuck in one spot, so they cannot move past each other. Instead, they just vibrate or 'shiver' in place. This is why a solid, like a rock or a wooden block, keeps its shape no matter where you put it. Even though a table looks perfectly still, the atoms inside it are constantly wiggling! Because they are so close, there is almost no empty space between them.
Quick Check
In a solid, do atoms move across the room or just wiggle in place?
Answer
They just wiggle or vibrate in place because they are packed too tightly to move past each other.
When we add heat, we are actually giving atoms more energy. Think of it like giving the atoms a sugary snack! In a liquid, the atoms have enough energy to break away from their fixed spots. They are still close together, but now they can slide and glide past one another. This is why water can flow and take the shape of whatever container it is in. If you pour cup of water into a bowl, the atoms slide around to fit the new shape, but they stay close enough to touch.
Let's look at how chocolate changes when it gets warm: 1. Start with a solid chocolate bar. The atoms are vibrating in a stiff grid. 2. Add heat from your hand or a stove. 3. The atoms gain energy and start to move faster. 4. Eventually, they move fast enough to slide past each other, and the chocolate becomes a gooey liquid!
Quick Check
What happens to the speed of atoms when you add heat?
Answer
The atoms move faster as they gain more energy.
If you keep adding heat, atoms get even wilder! In a gas, atoms have so much energy that they fly apart and zoom in all directions at high speeds. They are no longer packed together; instead, they are spread far apart with lots of empty space between them. A gas will expand to fill up an entire room or a balloon. Because the atoms are so spread out and moving so fast, you usually cannot see them with your eyes. They are like tiny bumper cars with engines that never stop!
Imagine a puddle on the sidewalk after a rainstorm: 1. The sun shines down, hitting the liquid water with heat energy. 2. The water atoms at the surface start sliding faster and faster. 3. When an atom gets enough energy, it breaks away from its neighbors entirely. 4. It zooms into the air as a gas (water vapor). This process is called evaporation!
Which state of matter has atoms that are locked in a neat, organized pattern?
What happens to atoms when a liquid turns into a gas?
Atoms in a liquid are spread further apart than atoms in a gas.
Review Tomorrow
In 24 hours, try to explain to a friend why steam takes up more space than an ice cube using the word 'energy'.
Practice Activity
Watch a pot of water come to a boil (with an adult). Can you see the 'Gas Zoom' happening as bubbles rise and turn into steam?