Unit A: Chemistry Quiz

Unit A: Chemistry

• Chemistry is the branch of science that identifies substances, investigates their properties and how they interact, combine and change, and uses these processes to create new substances.

Terms You Should Know

• Matter: Has mass and occupies space.
• Energy: Derived from chemical or physical resources.
• State: A physical condition determined by molecular structure.

Physical Properties of Matter

• Boiling/Condensation Point: The temperature at which a substance boils or condenses.
• Freezing/Melting Point: The temperature at which a substance freezes or melts.
• Malleability: The ability to be beaten or rolled into sheets.
• Ductility: The ability to be stretched without breaking.
• State: Existence as 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.

States of Matter

• Solid: Molecules held in a fixed pattern.
• Liquid: Molecules close together, free to move.
• Gas: Molecules widely separated.

Chemical Properties of Matter

• Ability to Burn: Combustion (flame, heat, light).
• Flash Point: Temperature needed to ignite a substance.
• 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 colour change (neutral).

Properties & Classification of Matter

• Matter: Pure substances (elements and compounds) or mixtures (solutions, mechanical mixtures, suspensions, colloids).

Breaking it Down: Pure Substances

• 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 (gold, oxygen, diamond, etc).
  • Compounds: Made up of more elements that are chemically combined in specific ratios (water, salt, crystals).

Breaking it Down: Mixtures

• Mixtures: Contain two or more pure substances.
  • Homogenous: Appears to be made of one substance and looks the same throughout (sugar & water mixed).
  • Heterogenous: Separate components are visible.
    • Suspension: Mixture in which particles are dispersed throughout a fluid (sand & water).
    • Colloid: Particles suspended, cannot be filtered apart easily (gelatin, milk).

Matter Changes

• Chemical Changes: A chemical reaction forms new products that have different properties than the original substances, is irreversible. (combustion, rotting, rusting, digestion).
• Physical Changes: The substance changes form but the chemical identity stays the same. Physical changes are often reversible (melting, shredding, boiling, chopping).

Identifying Chemical Reactions

• All chemical reactions are characterized by the formation of a new substance with new physical and/or chemical properties, and by the release or absorption of energy.

Ancient Chemistry

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

Food Chemistry

• The development of food preservation techniques was necessary for human survival and has been known for thousands of years. These techniques include cooking, freezing, drying, salting, smoking, spicing, fermenting.

Atomic Theory

• Our understanding of atomic structure has changed over time.

• Models of the atom are revised or new models emerge to incorporate new experimental evidence

Idea 1: Spontaneous Generation

• The idea that living things can be generated from non-living matter.

Idea 2: The Billiard Ball Model

• Dalton believed that matter is made up of indivisible atoms. Atoms of the same element are identical. Atoms combine in fixed ratios to form compounds.

Idea 3: The Raisin Bun Model

• Thomson proposed that atoms contain both positive and negative charges. Small negative charges are embedded in a positive particle.

Idea 4: The Planetary Model

• Rutherford suggested that the atom has a small, dense, positively charged nucleus (center). Negative electrons orbit the nucleus like planets around the sun.

Idea 5: The Bohr Model

• Bohr proposed that electrons orbit the nucleus in specific energy levels.

Idea 6: The Quantum Mechanical Model

• The modern model describes the electron's position in terms of probabilities. Electrons exist in certain regions around the nucleus.