Fundamental Principles of Matter and Energy in Chemistry

Properties of Matter

• Matter: Anything that has mass and volume.
• Physical Properties: Changes that occur when a substance alters its physical state, not its composition. Examples include melting, freezing, evaporation, boiling, vaporization, condensation, sublimation, and deposition.
• Chemical Properties: Changes that occur when a substance is converted into a different substance. Examples include rusting, corroding, tarnishing, combusting, and exploding.
• Pure Substance: A sample of matter with a definite, constant composition and distinct chemical properties.
• Mixture: Two or more substances combined such that each retains its own chemical identity.
• Elements: Substances consisting of one type of atom, distinguished by their atomic number (the number of protons in the nucleus).
• Compounds: Two or more elements chemically combined in a fixed ratio.
• Heterogeneous: Mixtures with one or more visible boundaries between components.
• Homogeneous: Mixtures with no visible boundaries, as components are individual atoms, ions, or molecules.

Energy and Atomic Theory

• Potential Energy: Energy due to the position of an object relative to others.
• Kinetic Energy: Energy due to the motion of an object.
• Significant Figures: Digits that carry meaning contributing to the precision of a measurement.
• Law of Conservation of Matter: In a chemical reaction, matter is neither created nor destroyed.
• Dalton (1800): Proposed the modern atomic theory.
• Democritus: A philosopher who created the first atomic theory; the word "atom" in Greek means "uncuttable."
• Lavoisier: Created the analytical balance.
• Thomson: Calculated the mass-to-charge ratio of cathode rays.
• Rutherford: Discovered the concept of radioactive half-life.
• Isotopes: Atoms of the same element with different numbers of neutrons.
• Covalent Bonds: The sharing of electrons between elements.
• Empirical Formula: The smallest whole-number ratio of moles of atoms present in a substance.
• Isomers: Compounds with the same molecular formula but different atomic connectivity.
• Classification of Elements: Elements can be metals, nonmetals, or metalloids.
• Molar Mass: The mass per mole of a substance's entities.