Ch 3 Sec 2: Changes of State Key Concepts: Freezing Vaporization What happens when a solid becomes liquid? Liquid to gas? Solid and gas? Evaporating Boiling Boiling point Condensation Key terms: Sublimation Melting Melting point

The states of matter There are 3 (really 4, but for now 3) states of matter: solid, liquid, and gas. Each of these states is also known as a phase. Elements and compounds can move from one phase to another when special physical forces (like temperature) are present.

Solids+energy->liquids Liquids+energy-> gases Minus energy (exothermic changes) means the processes reverse. If energy is added, like increasing temperature, or if energy is taken away (like freezing), those are physical changes.

Changes between solid and liquid Melting – change in state from solid to liquid. It REQUIRES energy to melt something (ENDOTHERMIC, M’DEARS) Melting point – the specific temperature at which melting occurs It is a characteristic of a substance At the melting point, particles are vibrating so fast they break free of their fixed positions What does this mean??

It means.. Changes in state have to do with changes of particle motion. When particles are vibrating in place because they are content where they are, they are solids. Adding energy to a solid (e.g. by heating it up) moves the particles around until they break free from one another and they become a liquid. THIS MEANS IT IS ENDOTHERMIC  it required energy.

Freezing Freezing is a change of state from liquid to solid. At its freezing temperature, particles of a liquid are moving so slowly they begin to form regular kinds of patterns. The particles form a solid, which we know has fixed position particles that just vibrate. Particles have LESS energy as solids, so they have LOST energy. THIS IS A LOSS OF ENERGY  EXOTHERMIC

Fossil fuels joke… well, not a good joke

Changes between liquid to gas Vaporization – when particles in a liquid GAIN enough energy to form a gas. Two types: Evaporation and boiling

Evaporation Vaporization that takes place only on the surface of the liquid is called evaporation. Those particles do what… GAIN ENERGY

I couldn’t find any funny and relevant science memes… so here are some cows..

Boiling Boiling occurs when a liquid changes to a gas below its surface as well as at the surface. (HAPPENS BOTH PLACES  ) … particles are… GAINING energy Boiling point – temp at which a liquid boils. It is affected by air pressure. The lower the pressure, the less energy needed for the particles to escape into the air.

Condensation Opposite of vaporization. It occurs when particles in a gas lose enough energy to become a liquid.

Changes between solid and gas Sublimation – particles of a solid do not pass through the liquid state as they form a gas. Example: Dry ice. Dry ice is solid carbon dioxide (CO2). Instead of melting, it changes directly to a gas, no liquid form is taken.

Solid to liquid takes energy (particles result in more energy) Liquid to gas takes energy (particles result in more energy) When the particles lose energy (exothermic), they will return to their previous states.

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