3.1 Matter and Energy

• Kinetic Theory of Matter:– All matter is made of atoms– Atoms always in motion; hotter = faster,

faster = hotter– Heavier particles move slower than

lighter at the same temperature

States of matter

• Solid: particles close together (still move … vibrate)

– definite Shape– definite Volume

• Liquid: particles are close but move freely … slide past each other– no definite Shape (container)– definite Volume

• Gas: particles are far apart … take available space

– no definite Shape– no definite Volume

• Plasma: electrons free from nucleus (ionized); like a gas with an electric charge

States of matter

• Phase changes: going from 1 state to another … a physical change, does not change the substance … involves energy– Exothermic: gives off/loses heat, becomes

colder (heat exits)• condensation: (gas to liquid)• solidification: (liquid to solid, also called freezing)• deposition: (gas to solid)

– Endothermic: absorbs energy, gets warmer (heat goes into it)• melt: (solid to liquid)• evaporate: (liquid to gas)• sublimate: (solid to gas)

States of matter

Conservation of Mass

• Law of Conservation of Mass: • Law of Conservation of Energy:

– mass and energy can not be created or destroyed. They only change form. You have the same mass and energy before a reaction as you would after.

• Temperature is not the only way to change state of matter. Pressure can also change state of matter.

• As pressure goes up, gas liquid solid• As pressure goes down, solid liquid gas

Phase diagrams

Phase diagrams

• Shows what happens as add heat. Adding energy doesn’t always change

the temperature!• When not changing phase: temperature

goes up as molecules move faster• During phase change: temperature

doesn’t change because energy is causing molecules to move farther apart.

Phase diagrams

Phase diagrams

• show combinations of temperature and pressures to achieve different phases.

• Triple point: temperature and pressure at which the substance can be a solid, liquid and gas all at once and stay that way.

• For water this is 0.01 °C and a pressure of 0.0060373 atm (1 atm = air pressure at sea level.

• Lines on graph represent phase changes (as either temperature or pressure change)