Chemistry Chapter: Pure Substances and Mixtures

Pure Substances vs. Mixtures

• Pure Substance: A material comprised of only one type of particle (atom or molecule). Composition is fixed. Examples: Water (H₂O), Oxygen (O₂), Gold (Au).
• Mixture: Two or more substances physically blended, not chemically combined. Examples: Saltwater, Air, Salad.

Atoms, Molecules, and Compounds

• Atom: Smallest unit of an element (e.g., Hydrogen (H), Oxygen (O)).
• Molecule: Two or more atoms chemically bonded (e.g., O₂, H₂O).
• Atomic Element: Element composed of single atoms (e.g., Helium (He), Iron (Fe)).
• Molecular Element: Element existing as molecules (two or more atoms of same element bonded) (e.g., O₂, N₂).
• Compound: Substance formed from two or more different elements chemically bonded (e.g., H₂O, CO₂).

Homogeneous vs. Heterogeneous Mixtures

• Homogeneous Mixture: Uniform composition; looks same throughout (e.g., Saltwater, Air, Coffee).
• Heterogeneous Mixture: Uneven composition; different parts are visible (e.g., Salad, Oil and Water, Cereal with Milk).

Physical vs. Chemical Properties

• Physical Property: Observed or measured without changing substance (e.g., color, density, melting point).
• Chemical Property: Describes a substance's ability to change into a new substance (e.g., flammability, reactivity with acid).

Definition of Chemistry

• Chemistry: The study of matter, its properties, and its changes.

Qualitative vs. Quantitative Data

• Qualitative Data: Describes qualities (e.g., color, smell, texture).
• Quantitative Data: Includes numerical values and measurements (e.g., mass = 5g, temperature = 100°C).

Chemistry Lab Safety Guidelines

• Wear safety goggles and gloves.
• No eating or drinking in the lab.
• Handle chemicals carefully.
• Know emergency procedures.

Accuracy and Percent Error

• Accuracy: How close a measurement is to the true value.
• Percent Error Formula: [(|Experimental Value - Actual Value|) / Actual Value] × 100%

Precision and Range Calculation

• Precision: How close multiple measurements are to each other.
• Range Formula: Highest Value - Lowest Value

Finding Density

• Density: Mass packed into a given volume.
• Formula: Density = Mass / Volume

Identifying Physical vs. Chemical Properties

• Physical Properties (do not change substance): Color, Shape, Melting Point, Density
• Chemical Properties (change substance): Rusting, Burning, Reactivity with Acid

Test your knowledge on the distinctions between pure substances and mixtures, as well as atoms, molecules, and compounds. This quiz covers the definitions and examples of homogeneous and heterogeneous mixtures to enhance your understanding of chemistry concepts.