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Matter Unit 3 - Lecture Flashcards

Matter

  • Definition: Anything that has mass and occupies space.

  • It cannot be created or destroyed; it only changes forms.

Classification of Matter

  • Pure Substances: Fixed composition.

    • Elements: Cannot be chemically broken down; consist of only one type of atom.

      • Atom: Fundamental unit of matter, defined by the number of protons.

      • Diatomic Elements: Seven elements naturally exist as molecules of two atoms (H{2}, N{2}, O{2}, F{2}, Cl{2}, Br{2}, I_{2}).

    • Compounds: Consist of two or more different atoms chemically bound together (e.g., H_{2}O, NaCl).

  • Mixtures: Variable composition.

    • Homogeneous Mixtures: Uniform throughout (e.g., air, saltwater).

    • Heterogeneous Mixtures: Not uniform throughout (e.g., salad, sand + water).

Properties of Matter

  • Physical Properties: Characteristics changeable without altering composition; directly observable (e.g., odor, color, state, melting point, density).

  • Chemical Properties: Characteristics describing a substance's ability to form new substances, or its behavior in interactions (e.g., flammability, ability to rust).

Changes in Matter

  • Physical Changes: Alterations in physical properties that retain the substance's identity (e.g., melting ice, cutting paper).

  • Chemical Changes: Processes where the original substance is converted into one or more new substances (e.g., paper burning, iron rusting).