what happens when molecules gain energy?
When molecules gain energy, their particles move faster, vibrate more, and can change state (like solid to liquid to gas), and with enough energy they can even break bonds and react chemically.
Basic idea
- Molecules are always in motion: vibrating, rotating, and moving from place to place.
- Adding energy (usually as heat or light) increases their kinetic energy, so they move more vigorously.
A simple picture: imagine people in a room. With little music (low energy), they shuffle slowly. Turn the volume way up (more energy), and everyone starts jumping, spinning, and bumping into each other more often.
What actually changes?
- Motion speeds up (kinetic energy)
- Atoms and molecules vibrate faster in place, rotate more quickly, and move around more if they are in a liquid or gas.
* This increase in molecular motion shows up as an increase in temperature of the substance.
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States of matter can change
As enough energy is added:- Solids: particles vibrate faster, weakening the forces holding them in fixed positions, so they can start to slide past one another, turning the solid into a liquid (melting).
* Liquids: particles move more freely until they can completely escape each other, turning the liquid into a gas (evaporation or boiling).
* Gases: already spread out, but extra energy makes molecules move even faster and farther apart, lowering density and increasing pressure in a container.
- Vibrations, rotations, and structure
- Vibrational energy: bonds stretch and compress like springs with larger amplitude and higher frequency.
* Rotational energy: molecules spin faster, which can slightly stretch the molecule and affect how it interacts with others.
* These changes can make molecules more reactive because their bonds are already “stressed.”
When energy is high enough
- Bond breaking and chemical reactions
- If a molecule absorbs enough energy to exceed its bond dissociation energy, chemical bonds can snap.
* Once bonds break, fragments can rearrange and form new bonds, which is the essence of a chemical reaction.
* The minimum energy needed to get a reaction going is called the activation energy; added energy helps molecules collide hard enough and in the right way to cross that barrier.
- Electronic excitation and light
- Light (photons) can be absorbed, boosting electrons to higher energy levels (excited states).
* When electrons fall back down, they can release energy as light, giving phenomena like fluorescence and phosphorescence.
Everyday examples
- Heating ice: water molecules vibrate more until they escape the rigid solid lattice and become liquid; with more energy, they escape entirely into the gas phase as steam.
- Hot air balloon: heating the air makes molecules move faster and spread out, lowering the air’s density so the balloon rises.
- Glow sticks or fluorescent paints: energy absorbed from a reaction or light pushes electrons to higher levels; when they relax, they emit visible light.
Information gathered from public forums or data available on the internet and portrayed here.
