Solid: Particles are tightly packed and have a fixed shape and volume.
Fixed shape and volume
Typically Regular arrangement of atoms/molecules
Incompressible - small space between atoms or molecules (Not easily Compressible)
Ex: Ice
Liquid: Particles are close together but can move past each other, taking the shape of their container.
No fixed shape but has a fixed volume (Takes shape of container)
No regular arrangement
Incompressible - small space between atoms or molecules (Not easily Compressible)
Ex: Liquid Water
Gas: Particles are far apart and move freely, taking the shape and volume of their container.
No Fixed shape or volume
No regular arrangement
Compressible - large space between atoms or molecules
Ex: Water Vapor
Properties of Matter
Physical Properties: characteristic that can change without changing the substance itself
Odor
Color
Volume
State (Solid, Liquid, Gas)
Density
Melting/Boiling Point
Chemical Properties: characteristic that describes the ability of a substance to change to a different substance
Corrosiveness
Flammability
Acidity
Toxicity
Changes of Matter
Physical Change: change in the form of a substance, does not affect chemical composition of substance:
Solid → liquid → gas
ex. Melting ice cubes (H2O molecules stay the same, motion of molecules change)
Chemical change: change of substance into another substance through a reorganization of atoms (ie. Chemical reaction):
Iron combining with oxygen to form rust
Evidence of chemical change:
Large excess of energy (heat/flame produced)
Evolution of a gas (gas is product of a reaction)
Change in properties of a substance (color change)
Precipitation (solid is produced)
Pure Substances:substance with constant composition (ex. Pure element or a pure compound)
Pure water only contains H2O molecules, water in nature contains H2O molecules and minerals (mixture)
Pure substances always have same physical and chemical properties
Key Concepts
Kinetic Molecular Theory: Explains the motion and behavior of gases:
Gases consist of small particles in constant, random motion.
Collisions between particles are perfectly elastic.
There are no attractive or repulsive forces between particles.
Boyle’s Law: \(P_1V_1 = P_2V_2\)
Describes the inverse relationship between pressure and volume at constant temperature.
Charles’s Law: \(\frac{V_1}{T_1} = \frac{V_2}{T_2}\)
Demonstrates the direct relationship between volume and temperature at constant pressure.
Dalton’s Law of Partial Pressures: \(P_{\text{total}} = P_1 + P_2 + P_3 + \dots\)
States that the total pressure of a gas mixture is the sum of the partial pressures of its individual gases.