Physical and Chemical changes

Chapter: ALL over the book

Physical Changes

1) Physical changes affect the physical properties of matter (things like size, shape, appearance)-ripping paper would be a physical change-other examples: changes of state, dissolving, crushing

Many physical changes can be undone

2) ALL changes of state are physical changes

A change of state is the change of a substance from one physical formto another

3) During a change of state, the energy of a substance changes, and particles speed up or slow down.

a)If energy is added to particles they go faster

b) If energy is removed, particles move slower.

4) Melting: change from a solid to a liquid.

a) The temperature at which a substance will melt is called the “melting point.”

5) When a solid absorbs more energy the particles will move faster and as they overcome their attraction to each other they transform into a liquid.

6) Freezing: change from a liquid to a solid.

a)The temperature at which a substance will freeze is called its freezing point.

b) The melting point and freezing point of a substance are the same temperature.

7) When liquids cool, they lose energy and the particles slow down and their attraction overcomes motion, and they become locked together to form a solid.

8) Vaporization: change from a liquid to a gas.

• there are two types -boiling and evaporation

a) boiling: liquid becomes gas throughout the liquid

b) evaporation: liquid becomes gas only on the surface of the liquid

9) Condensation: change from gas to liquid a- energy is removed, and particles slow down b- condensation point – temperature at which gas will become liquid

10) Sublimation: change from a solid directly to a gas

Chemical Changes

12) Chemical changes: one or more substances are changed into an entirely new substance with different properties.

13) Clues to chemical change: a) color changesb) fizzing or foamingc) heat changesd) production of sound, light, color

14) Chemical changes cannot be undone using normal physical processes.

15) In a chemical change, the items that combine together are called reactants, the resulting substance is called a product

Reactants . . . . . . . . . . . . . . . . . . . . . . . Products

Which type of change?

ACTION TAKING PLACEPHYSICAL OR CHEMICAL CHANGE.

Glass breaking  

Ice cube melting  

Candle burning  

Food digested in your stomach  

Glass breaking  

Marshmallow burning  

Lake freezing  

Bread baking  

Sugar dissolving  

Popsicle melting  

Gasoline burned in an engine  

Lake freezing