Chemistry: Pure Substances and Mixtures

Pure Substances and Mixtures

• Pure Substances: Composed of a single type of particle; have consistent properties throughout (e.g., elements and compounds).
• Mixtures: Combinations of two or more pure substances; properties can vary throughout the mixture.

Classification of Elements

• Metals: Typically solid (except mercury), good conductors of heat and electricity, and malleable. Examples include iron, copper, and gold.
• Non-Metals: Can be solid, liquid, or gas; poor conductors and often brittle. Examples are oxygen, sulfur, and bromine.
• Metalloids: Exhibit properties intermediate between metals and non-metals; semiconductors are important in electronics. Examples include silicon and arsenic.

Types of Compounds

• Acids: Substances that release hydrogen ions (H⁺) in solution; characterized by a sour taste and can conduct electricity. Examples include hydrochloric acid and sulfuric acid.
• Bases: Substances that release hydroxide ions (OH⁻) in solution; have a bitter taste and slippery feel. Common bases include sodium hydroxide and potassium hydroxide.

Homogeneous and Heterogeneous Mixtures

• Homogeneous Mixtures: Components are uniformly distributed; the mixture looks the same throughout and cannot be easily separated. Examples include saltwater and air.
• Heterogeneous Mixtures: Components can be seen and separated; the mixture has varying composition and properties. Examples include salad and sand.

Types of Mixtures

• Solutions: Mixtures where one substance is dissolved in another; they are homogeneous and transparent.
• Suspensions: Mixtures where particles are dispersed but not dissolved; they are heterogeneous and tend to settle over time. Examples include muddy water.
• Colloids: Mixtures with smaller particles that remain dispersed and do not settle; can appear homogeneous but scatter light. Examples include milk and fog.

Test your knowledge on the classification of elements, including metals, non-metals, and metalloids. Explore the different kinds of compounds, such as acids and bases, along with homogeneous and heterogeneous mixtures. This quiz covers essential concepts in chemistry relevant to pure substances and various types of mixtures.