STATES OF MATTER

First, a few important things: Arrangement and movement of particles in matter determines the phase There are FORCES OF ATTRACTION between these particles that determine properties like shape that help distinguish between different phases

Describing the States of Matter Materials can be classified as solids, liquids, or gases based on whether their: Shapes and volumes are definite (does not change) or Variable (does change).

Shape & Volume Some materials have a definite shape and volume, some do not. SHAPE and VOLUME are clues to how the particles within a material are arranged

SOLID LIQUID GAS http://www.harcourtschool.com/activity/states_of_matter/

Solids Solid: the state of matter in which materials have a definite shape and a definite volume. definite means shape and volume will NOT change if you move it from a desk drawer to a backpack definite does NOT mean that the shape or volume can never change For example: change shape of pencil when you sharpen it

Solids Example: Copper wire Arrangement of atoms: atoms are packed close together arranged in an regular pattern (almost all solids have some type of orderly arrangement of particles) page 69, fig.2

Liquids Liquid: the state of matter in which a material has a definite volume and a variable shape. A liquid always has the same shape as its container and can be poured from one container to another

Liquids Example: mercury is a liquid at room temperature Arrangement of atoms atoms are close together Arrangement more random than that of a solid (page 69, fig. 3)

Gases Gases: the state of matter in which a material has neither a definite shape nor a definite volume As gas takes the shape and volume of its container

Gases Example: air (mixture of gases), natural gas (used for heating), helium (gas found in balloons) Arrangement of atoms: atoms have more space between them than in solid/liquid form Not arranged in a regular pattern (very random, free to move)

Other States of Matter Plasma: found when a gas is heated to a temperature near 10,000 degrees Celsius                                                        Occurs on Earth mainly in lightening discharges and fluorescent lights Found most commonly in the universe (Sun and other stars) TV’s?

Other States of Matter Amorphous Solids: lack the orderly/rigid internal structure found in crystalline solids; "moves" over time Examples: rubber, asphalt, and glasses

Other States of Matter Bose-Einstein condensate (BEC) Bose and Einstein predicted this state of matter in the 1920’s. First observed in 1995. Occurs near absolute zero, 0K Atoms “clump” together and act as one giant particle.

Kinetic Theory Kinetic Theory: states that all particles of matter are in constant motion Kinetic Energy: the energy an object has due to its motion This is why, under ordinary conditions, copper is a solid, mercury a liquid, and helium a gas Faster an object moves = greater kinetic energy (abbreviated KE)

Explaining the Behavior of Gases Motion in Gases: There are forces of attraction among the particles in ALL matter. Particles in a gas are NEVER at rest Atoms move in a straight line until it collides with another atom or with a wall of the container

Explaining the Behavior of Gases What happens when 2 atoms collide: One atom may lose KE and slow down The other atom gains KE and speeds up TOTAL KE energy of the 2 atoms remains the SAME

KINETIC THEORY OF GASES: The constant motion of particles in a gas allows a gas to fill a container of any shape or size. Kinetic Theory as applied to gases has 3 main points.

KINETIC THEORY OF GASES: Particles in a gas are in constant, random motion The motion of one particle is unaffected by the motion of other particles unless the particles collide Forces of attraction among particles in a gas can be ignored under ordinary conditions WHAT?!?! WHY?!?! You were just told there were forces of attraction among the particles in ALL matter

EXPLAINING THE BEHAVIOR OF LIQUIDS A liquid takes the shape of its container because the particles in a liquid can flow to new locations.  The volume of a liquid is constant because the forces of attraction keep the particles together.

EXPLAINING THE BEHAVIOR OF LIQUIDS Tug-of-war between the constant motion of particles and the attractions among particles Think of trying to walk down the hall between classes Forces of attraction LIMIT the motion of particles in a liquid, the particles in a liquid CANNOT spread out and fill a container

EXPLAINING THE BEHAVIOR OF SOLIDS Solids have a definite volume and shape because particles in a solid vibrate around fixed locations Particles in a solid = polite audience in a movie theatre Movie is running, people stay in their seats People move within their seat but each person remains in essentially the same location during the movie - they have "FIXED" locations

EXPLAINING THE BEHAVIOR OF SOLIDS Vibration = repetitive back-and-forth motion Strong attractions among the atoms restrict their motion and keep each atom in a fixed location relative to its neighbors Each atom vibrates around its location but DOES NOT exchange places with a neighboring atom

3.2 – The Gas Laws

Pressure Pressure: the result of a force distributed over an area The smaller the area of impact is, the greater the pressure produced Example: walking on a frozen pond (bad ice) Snow shoes or tennis shoes? SI unit for pressure is the Pascal (Pa) or N/m2

Pressure Objects do not have to be large to exert pressure: Helium atoms in a balloon are constantly moving Pressure from a single helium atom is small But, there are 10^22 helium atoms in a small balloon!!! That many small collisions will produce noticeable pressure!

Pressure Collisions between particles of gas and the walls of a container cause pressure More collisions = greater pressure Speed and mass also affect pressure

Factors Affecting Gas Pressure Factors affecting pressure of gas in a closed container are: Temperature Volume The number of particles in the container

Temperature & Gas Pressure Raising the temperature of a gas will increase its pressure if the volume and the number of particles are constant Increase Temperature = Increase Pressure T P

Temperature & Gas Pressure Explains why pressure in tires increases after time spent driving... Constant motion of tires causes air inside to warm up As temperature rises, KE of the particles increases Increased KE causes the particles to move faster and collide more with the inner walls of the tires Increased number of collisions and increased force of impact causes the pressure in the tires to rise

Volume & Gas Pressure V P Reducing the volume of gas increases its pressure if the temperature of the gas and the # of particles are constant Decrease Volume = Increase Pressure V P

Breathing… This relationship shows what happens to the volume and pressure in your lungs when you breathe

Inhaling Diaphragm contracts Contraction causes the chest cavity to expand Increase in volume causes the air particles to spread out, lowering the pressure inside Now the pressure of the air outside your body is greater than inside This causes air to rush into your lungs

Exhaling Diaphragm relaxes Volume of chest cavity decreases Particles of air are squeezed into smaller volume, pressure inside increases Pressure is greater inside the chest cavity so the air is forced out

Particle Number & Pressure Increasing the number of particles will increase the pressure of a gas if the temperature and volume are constant Increase Particle Number = Increase Pressure P# P

Balloon Bursting This relationship explains why a balloon will burst if you blow too much air into it... The more particles of air in the same volume will cause more collisions, which increases pressure Eventually, the rubber cannot withstand the pressure and bursts!

Charles’ Law (proportional, same) Charles' Law states that the volume of a gas is directly proportional to its temperature (Kelvin) if the pressure and the number of particles are constant

Charles’ Law

Charles’ Law There is a direct relationship between volume and temperature If temperature increases, volume increases The temperature needed to produce a volume of 0 mL = 0 Kelvin = absolute zero = -273 degrees Celsius Absolute zero has not yet been reached!

Charles’ Law

Boyle’s Law (inverse, opposite) Boyle's Law states that the volume of a gas is inversely proportional to its pressure, if the temperature and number of particles are constant

Boyle’s Law

Boyle’s Law

Boyle’s Law The relationship is opposite for pressure and volume, as one increases, the other decreases! Example: squeezing a balloon...

Boyle’s Law P1V1 = P2V2

Combined Gas Law Describes the relationship among the temperature, volume and pressure of a gas when the number of particles is constant It describes the relationship between Charles' Law and Boyle's Law

Combined Gas Law