Chemistry Chapter 1: Matter and Properties

Definition of Matter

• Matter is anything that has mass and occupies space.
• Classified into two major categories: pure substances and mixtures.

Properties of Matter

• Properties are distinguishing characteristics used to identify matter.
• Types of properties include physical properties and chemical properties.

Physical Properties

• Can be observed or measured without changing the chemical composition.
• Examples:
  • Color, shape, texture, state, odor, taste.

Density

• Refers to the amount of matter in a given volume.
• Dense objects have more matter packed into the same space than less dense objects.

Malleability

• Ability of materials to be hammered or pressed into thin sheets.
• Most metals are malleable due to strong particle connections with some movement.
• Example: 30 grams of gold can cover 30 square meters.

Conductivity

• Ability of a material to transfer heat or electricity.
• Metals conduct heat, contrasted with materials like wood that do not.

Ductility

• Ability of materials to be drawn into thin wires.
• Gold is the most malleable and ductile metal; 1 ounce can be stretched into 80 kilometers of wire.
• Other ductile materials include copper and aluminum.

Intensive vs. Extensive Properties

• Intensive properties do not depend on quantity (e.g., ductility).
• Extensive properties change with the amount present (e.g., mass, volume).

Physical Changes

• Involves changes in appearance or state without altering chemical composition.
• Example: Copper wire drawing changes shape but remains copper.
• Boiling transforms liquid to vapor while retaining identity.

Chemical Properties

• Describe behavior of matter in the presence of other substances or under conditions.
• Key chemical properties include:
  • Reactivity: Stability or reactivity based on conditions.
  • Flammability: Whether a substance can burn.
  • Toxicity: Adverse effects on living organisms, often measured with an LD50 rating (lethal dose for half exposed).

Chemical Changes

• Occur when the chemical identity of a substance changes, indicating a chemical reaction.
• Composition changes alongside physical and chemical properties.