States of Matter

Holt: Chapter 3Fusion: Unit 3, Lesson 7

States of matter

• The physical forms in which a substance can exist• Solid• Liquid• Gas• All made of particles called atoms and molecules

Particles do not move fast enough to overcome the strong attraction between them. They are close together and vibrate in place.

Particles move fast enough to overcome the attraction between them. They are close together but can slide past one another.

Particles move fast enough to overcome almost all of the attraction between them. They are far apart and move independently of one another

Solids

• Have definite shape and volume• Particles are very close together• Attraction is stronger than the same substance in another form • Particles do move! They vibrate in place.• Two types• Crystalline

• Have orderly, 3-D arrangement of particles, ex. iron, diamond, ice• Amorphous

• Do not have special arrangement, ex. wax, glass, rubber

Particles do not move fast enough to overcome the strong attraction between them. They are close together and vibrate in place.

Liquids

• Definite volume, no definite shape• Particles slide past each other to take the shape of container

Particles move fast enough to overcome the attraction between them. They are close together but can slide past one another.

Unique characteristics of liquids

Surface tension• a force that acts on the particles

at the surface of a liquid that tends to minimize the area of the surface

Viscosity• a liquid’s resistance to flow• The stronger attraction between

molecules, the more viscous.

Gases

• No definite shape or volume- can be compressed• Particles move very quickly!• Particles have less attraction than solids or liquids of the same

substance.

Behavior of gases- the volume of a gas may be affected by temperature and pressure

Temperature• A measure of how hot or cold

something is; specifically, a measure of the movement of particles• Faster particles have more

energy• Faster particles cause expansion

Pressure• The amount of force exerted on

a given area of surface• “the number of times particles

of gas hit the sides of their container”

Gas laws

Boyle’s Law• P ↑ V ↓

Charles’ Law• T ↑ V ↑

Video clips demonstrating the gas laws

• https://www.youtube.com/watch?v=GcCmalmLTiU• https://

www.youtube.com/watch?v=kd1VxNwt2sQ&spfreload=1• https://

www.youtube.com/watch?v=ZgTTUuJZAFs• https://www.youtube.com/

watch?v=N5xft2fIqQU

Changes of StateHolt: Chapter 3, Section 3Fusion: Unit 3, Lesson 8

Energy and changes of state

• Change of state- the change of a substance from one physical form to another• All changes of state are physical changes• Particles of a substance move differently depending on state• Example: liquid water has more energy than ice, but steam has more

energy than even liquid water• To change a substance from one state or another, you must add or

remove energy

Melting: Solid to Liquid

• Adding energy increases temperature• Increasing temperature increases movement of particles• The temperature at which a substance melts is the melting point• Melting point is a physical property• Different substances have different melting points

Gallium has a melting point of 30⁰C, while normal body temperature is around 37 ⁰C. Table salt has a melting point of 801 ⁰C, so it would definitely NOT melt in your hand!

Remember what I said about solids…• The particles in a solid have strong attraction• To melt, a solid must overcome some of those attractions• Melting is *endothermic*• Endothermic means that energy is being added or gained

Freezing: Liquid to Solid

• The temperature at which a substance freezes is its freezing point• Freezing is the reverse process of melting, so they occur at the same

temperature.• Liquid water freezes at the same temperature at which ice melts- 0 ⁰C• Particles must slow down• Energy must be removed• *Exothermic* means that energy is removed from the substance

Add energy, ice melts

Remove energy, liquid water freezes

Evaporation: Liquid to Gas

• Evaporation is the change of a substance from a liquid to a gas.• Can occur at the surface of a liquid that is below its boiling point.

Boiling…what’s the difference?

• Boiling is the change of a liquid to a vapor, or gas, throughout the liquid. • Occurs when the pressure inside the bubbles equals the pressure

outside of the bubbles.

Condensation: Gas to Liquid

• The condensation point is the temperature at which a gas becomes a liquid• Condensation point is the same temperature as the boiling point at a

given pressure• Energy must be removed- exothermic

Sublimation: Solid to Gas

• Any change of state in which a solid changes directly into a gas• Particles must move from very tightly packed to spread apart• Particles must gain energy for this to happen- endothermic• Example: dry ice

Heating curve of water