Chemistry Fundamentals Quiz

Unit A: Chemistry

• Chemistry is the branch of science that identifies substances, investigates their properties, and studies how they interact, combine, and change to form new substances.

Matter

• Matter is a physical substance that has mass and occupies space.

Energy

• Energy is power derived from chemical or physical resources.

State

• State is a physical condition determined by molecular structure.

Physical Properties of Matter

• Boiling Point/Condensation Point: The temperature at which a substance boils or condenses.
• Freezing Point/Melting Point: The temperature at which a substance freezes or melts.
• Malleability: The ability of a substance to be beaten or rolled into sheets without crumbling.
• Ductility: The ability of a substance to be stretched without breaking.
• State: Existence as a solid, liquid, or gas.
• Crystal Formation: Crystalline appearance.
• Magnetism: Magnetic attraction between objects.
• Conductivity: Ability to conduct heat or electricity.
• Solubility: Ability to dissolve.
• Color: The color of the material.

Physical States of Matter

• Solids: Molecules held in a fixed pattern.
• Liquids: Molecules packed closely together, able to move freely.
• Gases: Molecules widely separated.

Chemical Properties of Matter

• Ability to Burn: Combustion (flame, heat, light).
• Flash Point: Temperature needed to ignite a flame.
• Behaviour in Air: Tendency to degrade, react, or tarnish.
• Reaction with Water: Tendency to corrode or dissolve.
• Reaction with Acids: Corrosion, sometimes bubble formation.
• Reaction with Heat: Tendency to melt or decompose.
• Reaction to Red/Blue Litmus: Red-acid; blue-basic; no color change-neutral.

Properties & Classification of Matter

• Matter can be classified as pure substances or mixtures.
  • Pure Substances: Contain only one type of particle, cannot be broken down into another substance by physical means.
    • Elements: Made up of one type of atom (e.g., gold, oxygen).
    • Compounds: Made up of more elements chemically combined in specific ratios (e.g., water, salt).
  • Mixtures: Contain two or more pure substances.
    • Homogeneous Mixtures: Appear to be made of one substance, look the same throughout (e.g., sugar and water).
    • Heterogeneous Mixtures: Separate components are visible.
      • Suspensions: Particles dispersed throughout a fluid (e.g., sand and water).
      • Colloids: Particles suspended, cannot be filtered apart easily, look like one substance (e.g., gelatin, milk).

Matter can Change

• Chemical Changes: A chemical reaction forms new products, altering the substance's composition. These are generally irreversible.
  • Examples: combustion, rotting, rusting, digestion
• Physical Changes: Matter changes form, but not its chemical identity. These are often reversible.
  • Examples: melting, shredding, chopping, boiling

Identifying Chemical Reactions

• Chemical reactions involve the formation of a new substance with new physical and chemical properties, and often involve the release or absorption of energy.

Ancient Chemistry

• Metallurgy: The science of producing and using metals.
  • Annealing: Heating metal to make it stronger and less brittle.
  • Smelting: Separating metals from compounds by melting them.

Food Chemistry

• Food preservation techniques, such as cooking, freezing, drying, salting, smoking, spicing, and fermenting, are essential for human survival.

Atomic Theory

• Our understanding of atoms has evolved over time. Models are revised to fit new evidence.
• Dalton's Model (Billiard Ball): Atoms are indivisible, identical atoms of an element, combine in fixed ratios.
• Thompson's Model (Raisin Bun): Atoms have a positive charge with embedded negative charges.
• Rutherford's Model (Planetary): Atoms have a small, dense, positive nucleus with negative electrons orbiting it.
• Bohr's Model: Electrons exist only in specific energy levels.
• Quantum Mechanical Model: Electrons' positions are described by probabilities; they can be found anywhere around the nucleus, but tend to be more frequent in certain regions.

Idea 1: Spontaneous Generation

• Aristotle's idea that living things can arise from non-living material.

Idea 2: The Billiard Ball Model

• Dalton's description of the atom characterized by indivisibility and the fixed ratios of atoms when combining to form compounds.

Idea 3: The Raisin Bun Model

• Thompson's model illustrating embedded electrons within a positively charged atom.

Idea 4: The Planetary Model

• Rutherford's nuclear model of the atom, with electrons orbiting the nucleus. Evidence came from experiments using gold foil and high-speed particles.

Idea 5: The Bohr Model

• Bohr's model suggesting electrons orbit the nucleus in discrete energy levels.

Idea 6: The Quantum Mechanical Model

• The modern model of the atom, describing electron positions using probabilities instead of fixed orbits.