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 ex its) condensation: (gas to liquid) solidification: (liquid to solid, also called freezing) deposition: (gas to solid) – Endothermic: absorbs energy, gets warmer (heat goes in to 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

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

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 atm (1 atm = air pressure at sea level. Lines on graph represent phase changes (as either temperature or pressure change)