Solids, Liquids, & Gases (Section 3.1)

Describing The States of Matter Materials can be classified as solids, liquids, or gases based on whether their shapes and volumes are definite or variable

Solid Set shape and volume Particles tightly packed Incompressible Solids - state of matter in which materials have a definite shape and a definite volume The term definite doesn’t mean that the shape or volume can never change Change the shape of a wire by bending it Change the shape of a pencil by sharpening it Most solids have an orderly arrangement of particles at the atomic level Like copper which have atoms packed close together and arranged in a regular pattern

Liquid Fluid Constant volume Shape of container Particles can move Incompressible

Gas Shape of container Fills the entire volume of the container Particles very far apart Compressible Air is a mixture of gases Gas- is the state of matter in which a material has neither a definite shape nor a definite volume Gas takes the shape and volume of its container The balloons are filled with helium gas. The volume and shape of the balloon is the same for the helium gas inside the balloon Helium gas can be compressed in metal cylinders such as gas tanks used to fill the balloons A small helium tank can fill 50 or more party balloons (much larger volume)

Other States of Matter On earth most matter exists as a solid, liquid, or gas But 99% of all matter observed in the universe exists as plasma, which is not common on earth Plasma exists only at extremely high temperatures such as those found on the sun or other stars Bose-Einstein Condensate (BEC) - state of matter that exist at extremely low temperatures, near -273°C

Kinetic Theory Kinetic energy - energy an object has due to its motion The Kinetic Theory of Matter says that all particles of matter are in constant motion According to the theory the particles inside a solid baseball are moving and the particles in the air the baseball travels through are moving too

Behavior of Gases Similar to balls during a game of billiards Ball move in straight lines until it strikes the sides or another ball Transfers kinetic energy Gas particles never rest Some move faster than others at average speed Collide, slow down, speed up but kinetic energy of the atoms remains the same There are forces of attraction among particles in all matter But for gas particles which are apart and moving fast the attractions are too weak to have an effect

Kinetic Theory of Gases The constant motion of particles in a gas allows a gas to fill a container of any shape or size 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

Behavior of Liquids Have kinetic energy but have a definite volume because the energy is lower so the atoms move slower than a gas at the same temperature Particles are also closely packed so the attractions between the particles affect the movement A liquid takes the shape of its container because particles in a liquid can flow to new locations The volume of a liquid is constant because forces of attraction keep the particles close together

Behavior of Solids Like people sitting in a movie theater Stay in their seats (“fixed”) but shift and move around in place Solids have a definite volume and shape because particles in a solid vibrate around fixed locations Vibration is repetitive back-and-forth motion Strong attractions restrict movement and keep each atom in a fixed location relative to its neighbors