Matter: Properties, States, and Phase Changes

Fundamentals of Matter

• Matter: Anything that has mass and occupies space.
• Mass: A measure of the amount of "stuff" or materials the object contains.
• Volume: A measure of the space occupied by the object.

States of Matter

• Solid: Matter that cannot flow, has definite shape, and definite volume.
• Liquid: Matter with a definite volume that takes the shape of its container.
• Gas: A substance without definite volume or shape that can flow.
• Plasma: Ionized gas containing positive ions and electrons.

Properties and Changes

• Physical Properties: Observed and measured without changing the material's composition (e.g., color, hardness, melting point, boiling point).
• Chemical Properties: Observed only by changing the composition of the material (e.g., ability to burn, decompose, ferment, react).
• Physical Change: Affects appearance or state but not identity (e.g., melting ice, cutting paper, dissolving table salt in water); often reversible.
• Chemical Change: Rearrangement of atoms during a reaction to form new substances (products) with different properties.
• Chemical Reaction: The process where reactants transform into entirely new substances called products.

Phase Changes

• Melting: Solid to liquid (add heat); e.g., Ice turning into water.
• Freezing: Liquid to solid (remove heat); e.g., Water turning into ice.
• Vaporization: Liquid to gas; includes Evaporation (slow, at surface) and Boiling (fast, throughout liquid).
• Condensation: Gas to liquid (lose heat); e.g., Water droplets on a cold glass.
• Sublimation: Solid directly to gas; e.g., Dry ice turning into carbon dioxide ($CO_2$) gas.
• Deposition: Gas directly to solid; e.g., frost forming on leaves.
• Ionization: Atoms or molecules gain or lose electrons to become charged particles called ions; e.g., formation of the aurora.
• Recombination: Ions regain electrons to become neutral atoms; e.g., turning off power to a neon light.
• Enthalpy of System: The internal heat/energy state that drives transitions between solid, liquid, gas, and plasma.

Chemical Equations

• Definition: Statements using words, formulas, or symbols to represent chemical reactions.
• Components: Made up of reactants (starting materials) and products (new substances formed).
• Example Balanced Net Chemical Equation: $2H_2 + O_2 \rightarrow 2H_2O$