stuff
Phase
A form or state that matter can be in, like solid, liquid, or gas. Based on density and particle movement.
Solid
A phase of matter that has a fixed shape and a fixed volume. The particles are packed tightly together, giving solids a high density.
Liquid
A phase of matter that has a definite volume but no fixed shape. The particles are close together but can slide around each other, so liquids have a medium density.
Gas
A phase of matter that has no fixed shape or volume. The particles are very spread out, which means gases have a low density.
Thermal energy
The energy something has because of the movement of its particles. More thermal energy usually means something feels hotter.
Movement
A change in position. In science, it often refers to how particles move within different phases of matter.
Density
How much mass (stuff) is packed into a certain amount of space. Something with high density has particles packed tightly together; something with low density has them more spread out.