Key Idea.
Section 1
The Microscopic World
Observable properties, such as a rock's hardness or water's flow, are determined by the behavior of tiny particles called molecules. The "macroscale" world we see is directly controlled by the "molecular scale" world we cannot see.
To understand why a substance acts the way it does, scientists model the arrangement and movement of these invisible particles.
Section 2
Vibration vs. Sliding
In a solid, molecules are locked into a rigid, fixed pattern. They possess energy but can only vibrate in place, which explains why solids keep their shape.
In a liquid, molecules break free from this rigid grid. They remain close together but gain enough freedom to slide past one another. This molecular sliding allows the liquid to flow and conform to the shape of a container.
Expand to review the lesson summary and core properties.
Section 1
The Microscopic World
Observable properties, such as a rock's hardness or water's flow, are determined by the behavior of tiny particles called molecules. The "macroscale" world we see is directly controlled by the "molecular scale" world we cannot see.
To understand why a substance acts the way it does, scientists model the arrangement and movement of these invisible particles.
Section 2
Vibration vs. Sliding
In a solid, molecules are locked into a rigid, fixed pattern. They possess energy but can only vibrate in place, which explains why solids keep their shape.
In a liquid, molecules break free from this rigid grid. They remain close together but gain enough freedom to slide past one another. This molecular sliding allows the liquid to flow and conform to the shape of a container.