Physical and Chemical Changes

• Physical and Chemical Changes will be discussed
• The meeting will take attendance and do a science routine
• There will be a check of worksheets and a discussion
• Meeting will wrap up

Physical Change

• Physical change does not produce a new substance with new properties
• The appearance of the materials change, but it is still the same material

Melting

• Ice melting into water qualifies as a physical change
• The substance is still water (H2O) whether it is solid or liquid
• The temperature at which a solid turns to liquid is known as the melting point

Evaporation

• Evaporation is when a liquide turns into a gas
• This occurs when molecules at a liquid's surface gain enough energy to break free from the liquid and become a gas

Condensation

• Condensation is the process when a liquid forms from gas or vapor
• Water vapor condenses when cooled below it's dew point
• Dew point is the temperature at which moist air becomes saturated and forms dew when it comes in contact with the ground

Solidification

• Solidification, otherwise known as freezing, is the process where a liquid changes into a solid
• This happens when the liquid's temperature decreases to its freezing point
• When the liquid molecules lose energy they arrange themselves into a more structured, solid form

Sublimation

• Sublimation is a change in the state of matter from solid to gas, without passing through the liquid state
• This happens when molecules of a solid gain enough energy to overcome their fixed positions and enter the gaseous state

Phase Changes

• A solid can freeze and melt into liquid
• A solid can sublimate directly into a gas
• A liquid can condense and vaporize into gas
• A gas can deposition directly back into a solid

Chemical Change

• Chemical change is a process where one or more substances are transformed into new and different substances
• Unlike physical changes where the appearance of a substance only changes, chemical changes result in the formation of new materials with different properties
• Chemical reactions are the processes by which chemicals interact to form new chemicals with different compositions

Characteristics Of Chemical Change

• New substances are formed in chemical change
• Gas, heat, light, or a solid (precipitate) can be produced
• It is usually irreversible
• Large energy changes occur

Evidences Of Chemical Reaction

• Combustion: Burning wood or fossil fuels
• Rusting: Iron reacting with oxygen to form rust
• Cooking/baking: Transforming raw ingredients into cooked food
• Digestion: Food breaking down in the stomach to provide energy
• Neutralization: Acid reacting with a base to form salt and water
• Change in intrinsic property
• Production of light
• Evolution of Gas
• Temperature change
• Formation of precipitate