Grade 9 Ontario Science Study Notes

CHEMISTRY

Lab Safety and Equipment

  • Wear safety goggles, gloves, and a lab coat to protect yourself.
  • Know the locations of the eyewash station, fire extinguisher, and safety shower in case of emergencies.
  • Never eat or drink in the lab to avoid accidental ingestion of chemicals.
  • Common lab equipment includes beakers, test tubes, Bunsen burners, tongs, and graduated cylinders.

Chemical and Physical Properties & Changes

  • Physical Property: A characteristic that can be observed without changing the substance's composition (e.g., color, melting point).
  • Chemical Property: A characteristic that describes how a substance reacts with other substances (e.g., flammability, reactivity).
  • Physical Change: A change in the state or appearance of a substance that does not change its composition (e.g., change in state like ice melting).
  • Chemical Change: A change that results in the formation of a new substance (e.g., rusting, burning).

Density

  • Definition: Density is the mass per unit volume of a substance.
  • Formula: D=mVD = \frac{m}{V}, where D is density, m is mass, and V is volume.
  • Units: Density is commonly expressed in grams per cubic centimeter (g/cm3g/cm^3) or grams per milliliter (g/mLg/mL).

Identifying Gases

  • Oxygen: Relights a glowing splint.
  • Hydrogen: Produces a "pop" sound when exposed to a lit splint.
  • Carbon Dioxide: Turns limewater milky.

Bunsen Burners

  • Blue Flame: Indicates a hotter flame; achieved by opening the air hole.
  • Yellow Flame: Indicates a cooler/safety flame; achieved by closing the air hole.

History of the Atom

  • Dalton: Proposed that atoms are solid, indivisible spheres.
  • Thomson: Discovered electrons and proposed the plum pudding model, where electrons are scattered within a positive medium.
  • Rutherford: Conducted the gold foil experiment, leading to the discovery of the nucleus as small, dense, and positively charged.
  • Bohr: Proposed that electrons orbit the nucleus in specific shells or energy levels.

Subatomic Particles

  • Protons: Positively charged particles located in the nucleus.
  • Neutrons: Neutrally charged particles located in the nucleus.
  • Electrons: Negatively charged particles that orbit the nucleus.

Ions and Isotopes

  • Ion: An atom that has gained or lost electrons, resulting in an overall charge.
  • Isotope: Atoms of the same element with different numbers of neutrons.

Elements, Compounds, Mixtures

  • Element: A pure substance consisting of only one type of atom.
  • Compound: A substance formed when two or more elements are chemically combined.
  • Mixture:
    • Homogeneous: A mixture with uniform composition throughout (e.g., saltwater).
    • Heterogeneous: A mixture with visibly different parts (e.g., salad).

Periodic Table Trends

  • Groups: Vertical columns in the periodic table; elements in the same group have the same number of valence electrons.
  • Periods: Horizontal rows in the periodic table; elements in the same period have the same number of electron shells.
  • Reactivity: Alkali metals are the most reactive metals, and halogens are the most reactive non-metals.

Evidence of a Reaction

  • Color change.
  • Gas production.
  • Temperature change.
  • Formation of a precipitate (solid).

Ionic Bonds/Compounds

  • Formed between a metal and a non-metal.
  • Involve the transfer of electrons.
  • Conduct electricity when dissolved in water.

Bohr-Rutherford Diagrams

  • Show the number of protons and neutrons in the nucleus and the arrangement of electrons in shells around the nucleus.

Lewis Dot Diagrams

  • Show only the valence electrons (dots) around the element symbol.

SCIENTIFIC INQUIRY

Observations vs. Inferences

  • Observation: Direct information gathered using the senses.
  • Inference: An interpretation or conclusion based on observations.

Qualitative vs. Quantitative

  • Qualitative: Descriptive data (e.g., blue, rough).
  • Quantitative: Numerical data (e.g., 10 cm, 5 kg).

Process of an Experiment

  • Question > Hypothesis > Experiment > Data > Conclusion

Variables

  • Independent: The variable that is changed by the scientist.
  • Dependent: The variable that is measured; the result.
  • Controlled: Variables that are kept the same throughout the experiment.

Calculating Slope

  • Formula: Slope=RiseRun=y2−y1x2−x1Slope = \frac{Rise}{Run} = \frac{y2 - y1}{x2 - x1}

ELECTRICITY

Triboelectric Series

  • Ranks materials based on their tendency to gain or lose electrons.
  • Determines which material becomes positively charged and which becomes negatively charged when rubbed together.

Representing Electric Circuits

  • Series Circuit: A circuit with only one path for current to flow.
  • Parallel Circuit: A circuit with multiple paths for current to flow.

Parts of an Electric Circuit

  • Power source (e.g., battery).
  • Conductors (e.g., wires).
  • Load (e.g., light bulb).
  • Switch.

Voltage, Current, Resistance

  • Voltage (V): The electric potential energy per unit charge, measured in Volts.
  • Current (I): The rate of flow of electric charge, measured in Amps.
  • Resistance (R): The opposition to the flow of electric charge, measured in Ohms.

Ohm's Law

  • V=I×RV = I \times R

Kirchhoff's Laws

  • Series Circuits: Voltage adds up across components, and the current is the same throughout the circuit.
  • Parallel Circuits: Current adds up across branches, and the voltage is the same across all branches.

Static Electricity

  • An imbalance of electric charges on the surface of a material.

Charging Methods

  • Friction: Charging by rubbing two objects together.
  • Contact: Charging by touching a charged object to a neutral object.
  • Induction: Charging by bringing a charged object near a neutral object, causing a redistribution of charge.

ECOLOGY

Food Webs and Chains

  • Food Chain: A single pathway of energy flow in an ecosystem.
  • Food Web: Interconnected food chains showing the complex feeding relationships in an ecosystem.

Terminology

  • Producer: An organism that makes its own food (e.g., plants).
  • Consumer: An organism that eats other organisms (e.g., herbivore, carnivore).
  • Decomposer: An organism that breaks down dead organic matter (e.g., fungi, bacteria).

Trophic Levels

  • Levels of energy flow in an ecosystem: Producer > Primary Consumer > Secondary Consumer > Tertiary Consumer.

Biotic vs. Abiotic

  • Biotic: Living components of an ecosystem (e.g., animals, plants).
  • Abiotic: Non-living components of an ecosystem (e.g., sunlight, water).

Photosynthesis and Cellular Respiration

  • Photosynthesis: CO<em>2+H</em>2O+sunlight→glucose+O2CO<em>2 + H</em>2O + sunlight \rightarrow glucose + O_2
  • Respiration: glucose+O<em>2→CO</em>2+H2O+energyglucose + O<em>2 \rightarrow CO</em>2 + H_2O + energy

Factors Affecting Population Growth

  • Food availability, predators, disease, space.

Nutrient Cycles

  • Water Cycle: Evaporation, condensation, precipitation.
  • Carbon Cycle: Respiration, combustion, photosynthesis.
  • Nitrogen Cycle: Nitrogen fixation, decomposition.
  • Phosphorus Cycle: Weathering of rocks, uptake by organisms.

Species Interactions

  • Mutualism: Both species benefit from the interaction.
  • Parasitism: One species benefits, and the other is harmed.
  • Commensalism: One species benefits, and the other is unaffected.

Climate Change in Ecosystems

  • Affects species survival, migration patterns, and ecosystem balance.

Population Graphs

  • Show changes in population size over time.
  • Can show exponential or logistic growth patterns.