States of Matter

Core concept

These differences in behaviour arise directly from how tightly the particles are packed and how much energy (movement) they have — solids have the least particle movement, gases have the most. A fourth state, called plasma, exists at extremely high temperatures (like inside the Sun or in lightning), where particles are so energetic that they break apart into charged particles, though this is not commonly studied at this level. Understanding states of matter helps explain everyday changes, like why ice melts or why perfume spreads through a room.