STATES OF MATTER

MATTER

• Affected by temperature and pressure

• A change in temperature and/or pressure can change the state of matter of a substance

Kinetic Theory – Energy in MotionThree assumptions of how particles in matter behave

1. All matter is made of small particles -

atoms, molecules and ions

2. These particles are in constant motion. The motion has no pattern.

3. These particles are colliding or crashing into each other and into the walls of their container.

Thermal Energy

• Thermal energy is the total energy of the particles in a material.

• Thermal energy includes kinetic energy and potential energy

• Solid particles do not appear to be moving but they are! Solid particles move slowly.

Absorb or ReleaseThermal Energy

When particles absorb thermal energy then – Temperature increases or – Temperature remains constant and particles

transition to more energetic phase of matter

When particles release thermal energy then– Temperature decreases or – Temperature remains constant and particles

transition to less energetic phase of matter

Temperature

• Measure of the average kinetic energy of the vibrating or moving atoms or molecules of a substance

• Absolute zero = no movement

• Heat= the total kinetic energy of a substance

Pressure

• The force per unit area applied on a surface in a perpendicular direction

These gas molecules are constantly moving in random directions. When a molecule hits the container wall (green), it exerts a tiny force on the wall. The sum of these tiny forces, divided by the interior surface area of the container, is the pressure.

One atmosphere is defined as the pressure caused by the weight of all the overlying air at sea level

or 14.7 pounds per square inch (psi).

Solid

• Low Temperature and/or High Pressure

• Low Kinetic energy

• Definite pattern resulting in definite volume and definite shape

• Can be an atom, ion or molecule

• Usually in crystalline form, although some are glass

http://www.chem.purdue.edu/gchelp/liquids/character.html

http://www.chem4kids.com/files/matter_solid.html

Itl.chem.ufl.edu/2045_s00/lectures/fg11_001.GIF

Liquid

• Less Pressure, More Kinetic Energy

• Definite volume, no definite shape

• Melting point= the vibrations of the particles cause the forces holding the solid together to break

• These forces are called chemical bonds

http://www.chem.purdue.edu/gchelp/liquids/character.htmlhttp://www.mcwdn.org/chemist/liquids.html

Bonds

• Solid water has MORE H-bonds (4) than liquid water (~2 )

Itl.chem.ufl.edu/2045_s00/lectures/fg11_001.GIF

If solids are more compact and more dense due to high pressure, why does solid water float?

Most substances contract when temperatures decrease because the particles move closer together, but not water!

Why is solid ice less dense than liquid water?

• Water expands when it freezes into ice because water is a polar molecule.

• The negative and positive charges are attracted to one another so when they line up that leaves empty space. Therefore water expands when it freezes or changes from a liquid to a solid.

Gas

• Least pressure, most kinetic energy• No definite shape, no definite volume

• Evaporation (Liquid to Gas) is the boiling point of the liquid

• Gravity – prevents escape of gases

• Gas would escape to space if not for the Earth’s gravity

http://www.chem.purdue.edu/gchelp/liquids/character.htmlhttp://www.mcwdn.org/chemist/gases.html

Itl.chem.ufl.edu/2045_s00/lectures/fg11_001.GIF

http://en.wikipedia.org/wiki/Liquid

Plasma• Hot ionized gas with energy• temperatures above 5000°C• Violent collisions cause electrons

to be knocked off• Stars, lightning, neon signs,

solar wind, auroras, comet tails,

welding arcs, fireball made by

nuclear weapons

http://en.wikipedia.org/wiki/Plasma_(physics)

http://dewa.com/animated/

Earth’s Plasma Fountain

http://en.wikipedia.org/wiki/Plasma_(physics)

Conservation of Matter and Energy

• During an ordinary chemical change, there is no detectable increase or decrease in the quantity of matter.

LAW

• Energy cannot be created or destroyed, it can only change form.

http://dewa.com/animated/

Condensation – Gas to a LiquidReleases Thermal Energy

http://ga.water.usgs.gov/edu/watercyclecondensation.html

http://en.wikipedia.org/wiki/Condensation

http://en.wikipedia.org/wiki/Condensation

Freezing - Liquid to a SolidReleases Thermal Energy

Freezing is an exothermic process

Melting - Solid to a Liquid

Absorbs Thermal Energy

For water the temperature has to be a little over zero degrees Celsius. If you were salt, sugar, or wood your melting point would be higher than water. 

Evaporation – Liquid to a GasAbsorbs Thermal Energy

Sublimation – Solid to a GasAbsorbs Thermal Energy

• Skip a Phase: Solid to a Gas

• Carbon dioxide (dry ice), Naphthelene (moth balls) and snow sublime

http://ga.water.usgs.gov/edu/watercyclesublimation.htmlhttp://ga.water.usgs.gov/edu/watercyclesublimation.html

*** Condensation & evaporation are opposite (type error)

Absorb or Release Thermal Energy?

Which phase is missing on this diagram?

http://www.cmmacs.ernet.in/~himesh/Hydrosphere%20Components.gif

Recap of Phase Changes

• Melting – Solid to

• Freezing – Liquid to

• Evaporation – Liquid to

• Condensation – Gas to

• Sublimation – Solid to