What Is Melting

Melting is a physical change that happens when a solid turns into a liquid. This change occurs when heat energy is added to the solid. Understanding melting helps us explain many everyday events, from ice cubes disappearing in a glass of water to snow turning into puddles on a warm spring day.

All matter is made up of tiny particles that are always moving. In a solid, these particles are packed closely together and vibrate in place. They hold their shape because the particles don't have enough energy to move freely. When you add heat to a solid, the particles gain energy—the ability to do work or cause change. As the particles gain more energy, they start to vibrate faster and faster.

When enough heat is added, the particles gain so much energy that they can break free from their fixed positions. They begin to slide past each other instead of just vibrating in place. This is when the solid becomes a liquid. The melting point is the specific temperature at which this change happens. Different substances have different melting points. Ice melts at 32°F (0°C), while chocolate melts at about 86°F (30°C).

Ice turning into water is the perfect example of melting. When you take an ice cube out of the freezer, it is cold and solid. The water particles in the ice are locked in place, vibrating but not moving around. As the ice sits at room temperature, heat from the warmer air moves into the ice. This heat gives the water particles more energy. Soon, the particles are moving fast enough to slide past each other, and the ice becomes liquid water.

An important fact about melting is that the substance—the type of matter—stays the same. Ice and liquid water are both made of water particles. Only the state of matter changes. The solid becomes a liquid, but it's still the same substance. If you froze the water again, it would turn back into ice. This is different from other changes, like burning wood, where the substance itself changes into something completely different.

Think of melting like children on a playground. When they stand in tight rows for a class photo, they're like particles in a solid—close together and in fixed positions. When the teacher says they can play, they spread out and move around freely, like particles in a liquid. The children are still the same people, just in a different arrangement.

Interesting Fact: The metal gallium has a melting point of only 85.6°F (29.8°C), which means it can melt in your hand! Scientists use this unusual metal in thermometers and electronics.