Chemical Properties and Changes How a substance changes when it comes into contact with another substance Chemical Change Affects electronic structure of atoms Changes the arrangement of Atoms Which atoms are part of a substance Change Ratios of Atoms

Conservation of Matter Matter is neither created nor destroyed, but only changes forms No new atoms are created in normal circumstances This is true for: Wood Burning Plants Growing Other everyday occurrences

Nuclear Changes In very special circumstances, an atom can undergo a change in its nucleus. Can loose gain some protons or neutrons Can split into two smaller atoms Two atoms can combine into one big one Happens in: The Sun Nuclear Power plants Nuclear Weapons

Changes in State A change in state is a physical change Solid – Liquid Liquid-Gas State changes occur because of changes in thermal energy. As thermal energy increases or decreases, particle movement changes, causing a state change

Freezing and Melting When a liquid is cooled, its particle move slower, until it becomes a solid – Freezing or Solidifying What a solid is heated, the molecules warm up, and are free to move around each other – Melting, Liquefying

Vaporization Vaporization - When a liquid turns into a gas Boiling – Vaporization where the liquid is hot enough to quickly turn into a gas Occurs at the boiling point Boiling point increases with increase air pressure.

Evaporation Evaporation – When a liquid turns to gas below the boiling point Only occurs at the surface Water molecules collide and hit each other into the gas phase This takes away some energy from the molecule that stays in the liquid, cooling the liquid. Sweating keeps you cool

Condensation Condensation – When a gas turns back into a liquid The gas slowly down enough and sticks to something to become liquid

Sublimation Sublimation – When a solid turns immediately into a gas, or a gas turns immediately into a solid Frost is an example of water vapor forming a solid immediately Dry Ice, or Solid Carbon Dioxide turns from a solid to a gas immediately

Changes in States Review