Physical and chemical properties are key to understanding matter's behavior. Physical properties, like melting point and density, describe observable characteristics without changing composition. They help identify and classify substances based on their unique attributes.

Chemical properties reveal how substances interact and change during reactions. These include reactivity, flammability, and stability. Understanding both types of properties is crucial for predicting and explaining matter's behavior in various situations.

Physical Properties

Observable Characteristics

• Physical properties describe observable characteristics of matter without changing its chemical composition
• Malleability refers to a material's ability to be hammered or pressed into thin sheets without breaking (gold, silver)
• Ductility measures how easily a material can be drawn into wires without breaking (copper, aluminum)
• Conductivity represents a substance's ability to transmit heat or electricity (metals generally have high conductivity)

Thermal Properties

• Melting point indicates the temperature at which a solid changes to a liquid state (water melts at 0°C)
• Boiling point denotes the temperature at which a liquid changes to a gas at standard atmospheric pressure (ethanol boils at 78.37°C)
• These points vary depending on the substance and can be used for identification purposes
• Heat capacity measures the amount of heat required to raise the temperature of a substance by one degree (water has a high heat capacity)

Additional Physical Properties

• Density calculates the mass per unit volume of a substance (lead is denser than aluminum)
• Solubility describes how well a substance dissolves in a solvent (sugar dissolves easily in water)
• Hardness measures a material's resistance to scratching or indentation (diamonds are extremely hard)
• Color results from how a substance interacts with light (chlorophyll makes plants appear green)

Chemical Properties

Reactivity and Interactions

• Chemical properties describe a substance's ability to undergo chemical changes or reactions
• Reactivity measures how readily a substance undergoes chemical reactions with other substances
• Highly reactive elements like sodium react vigorously with water, while noble gases have low reactivity
• Oxidation involves a substance combining with oxygen, often resulting in corrosion (rusting of iron)
• Acidity or basicity determines how a substance behaves in aqueous solutions (lemons are acidic)

Combustion and Stability

• Flammability indicates how easily a substance ignites and burns in the presence of oxygen
• Gasoline is highly flammable, while materials like concrete have low flammability
• Combustibility refers to a material's ability to burn, which differs from flammability in some cases
• Stability describes a substance's resistance to decomposition or chemical change over time
• Some compounds, like nitroglycerin, are unstable and prone to rapid decomposition

Chemical Behavior in Reactions

• Redox potential measures a substance's tendency to gain or lose electrons in chemical reactions
• Catalytic behavior allows some substances to speed up chemical reactions without being consumed
• Photochemical properties describe how a substance reacts when exposed to light (photosynthesis in plants)
• Radioactivity involves the spontaneous emission of particles or energy from unstable atomic nuclei