SNC 2DB Science Exam Comprehensive Study Guide

Principles of Chemistry in the SNC 2DB Curriculum

Atomic Structure and the Periodic Table

• Organization of the Periodic Table: The periodic table is organized by increasing atomic number. Key groups include:

  • Group $1$ (Alkali Metals): Highly reactive metals with $1$ valence electron.
  • Group $2$ (Alkaline Earth Metals): Reactive metals with $2$ valence electrons.
  • Group $17$ (Halogens): Highly reactive non-metals with $7$ valence electrons.
  • Group $18$ (Noble Gases): Stable, non-reactive gases with full outer shells ($8$ valence electrons, except Helium which has $2$).

• Valence Electrons and Ions: Atoms form ions to achieve a stable octet (a full valence shell).

  • Cations: Positive ions formed when an atom loses electrons. Metals typically form cations.
  • Anions: Negative ions formed when an atom gains electrons. Non-metals typically form anions.
  • Isoelectronic Species: Ions or atoms that have the same number of electrons (e.g., $Ne$, $Na^{+}$, and $F^{-}$ all have $10$ electrons).

• Bohr-Rutherford Diagrams for Ions: When drawing a Bohr diagram for an ion, the electron count is adjusted based on the charge. For example, a Magnesium ion ($Mg^{2+}$) has $10$ electrons rather than the $12$ seen in the neutral atom. The diagram is usually placed in brackets with the charge indicated in the top-right corner ($[Mg]^{2+}$).

• Oxidation Numbers: These represent the charge an atom would have if the compound was composed of ions. By knowing the oxidation number, one can determine the element's group (e.g., an oxidation number of $+1$ generally refers to Group $1$ elements).

Chemical Reactions and Properties

• Physical vs. Chemical Properties:

  • Physical Properties: Characteristics observed without changing the identity of the substance (e.g., color, luster, density, melting point, solubility).
  • Chemical Properties: Characteristics that describe a substance's ability to undergo a specific chemical change (e.g., flammability, reactivity with acid, toxicity).

• Reactants and Products: In a chemical equation, reactants are the starting materials (located on the left side of the arrow), and products are the substances formed (located on the right side).

• Chemical Nomenclature: Determining the correct name or formula for a compound.

  • Ionic Compounds: Formed between a metal and a non-metal. The metal name comes first, and the non-metal name ends in the suffix "-ide" (e.g., $NaCl$ is Sodium Chloride).
  • Polyatomic Ions: Groups of atoms that act as a single unit with a charge (e.g., Sulfate $SO_4^{2-}$).

• Balancing Equations: Chemical equations must be balanced to satisfy the Law of Conservation of Mass, states that mass is neither created nor destroyed in a chemical reaction. The number of atoms for each element must be equal on both the reactant and product sides.

• Precipitate: A solid that forms and settles out of a liquid mixture during a chemical reaction between two clear solutions ($(aq) + (aq) \rightarrow (s) + (aq)$).

Acids, Bases, and Neutralization

• Properties of Acids and Bases:

  • Acids: Taste sour, conduct electricity, and react with metals to produce Hydrogen gas ($H_2$).
  • Bases: Taste bitter, feel slippery, and conduct electricity.

• Indicators and Color Changes:

  • Litmus Paper: Acids turn blue litmus paper red. Bases turn red litmus paper blue.
  • Phenolphthalein: Remains colorless in acids but turns bright pink/magenta in bases.

• Neutralization Reactions: A specific type of double-displacement reaction where an acid and a base react to produce water and an ionic salt.     $\text{Acid} + \text{Base} \rightarrow \text{Water} + \text{Ionic Salt}$     Example: $HCl_{(aq)} + NaOH_{(aq)} \rightarrow H_2O_{(l)} + NaCl_{(aq)}$

• Metal and Acid Reaction: When a metal reacts with an acid, it typically produces a salt and Hydrogen gas.     $\text{Metal} + \text{Acid} \rightarrow \text{Salt} + H_{2(g)}$

Biology and Life Systems

Cell Theory and Division

• Levels of Biological Hierarchy: The organization of living things follows a specific sequence: Cell $\rightarrow$ Tissue $\rightarrow$ Organ $\rightarrow$ Organ System $\rightarrow$ Organism.

• Why Cells Divide: There are three primary reasons for cell division:

  1. Growth: To increase the size of an organism.
  2. Repair: To replace damaged or dead cells.
  3. Reproduction: To create offspring (asexual or sexual).

• Types of Cells:

  • Prokaryotic Cells: Simple cells without a nucleus or membrane-bound organelles (e.g., Bacteria).
  • Eukaryotic Cells: Complex cells containing a nucleus and membrane-bound organelles (e.g., Plant and Animal cells).

• Plant vs. Animal Cells:

  • Plant Cells: Contain a Cell Wall for structure, Chloroplasts for photosynthesis, and a large Central Vacuole.
  • Animal Cells: Contain Centrioles for division and usually have many small vacuoles.

• Cellular Respiration: The process by which cells convert glucose into energy.

  • Reactants: Glucose and Oxygen.
  • Products: Carbon Dioxide, Water, and Energy (ATP).
  • Equation: $\text{C}_6\text{H}_{12}\text{O}_6 + 6\text{O}_2 \rightarrow 6\text{CO}_2 + 6\text{H}_2\text{O} + \text{ATP (Energy)}$

Tissues and Organ Systems

• Four Types of Animal Tissues:

  1. Epithelial Tissue: Lines body surfaces and organs; provides protection (e.g., skin).
  2. Connective Tissue: Provides support and structure (e.g., bone, blood, tendons).
  3. Muscle Tissue: Allows for movement (e.g., skeletal, cardiac, smooth).
  4. Nervous Tissue: Conducts electrical signals for communication (e.g., brain, nerves).

• Muscular-Skeletal Connection: Muscles attach to bones via Tendons to facilitate movement through contraction and relaxation.

• Cancer and Tumours: A tumor is a mass of cells with uncontrolled growth. Metastasis is the process where cells break away from a primary tumour and spread to other parts of the body to form secondary tumours.

Plant Biology and Systems

• Function of Stomata: Small pores on the underside of leaves that facilitate gas exchange (allowing $\text{CO}_2$ to enter and $\text{O}_2$ to exit) and regulate water loss via transpiration.

• Plant Tissues and Analogies:

  • Vascular System in Plants: Composed of Xylem (water transport) and Phloem (nutrient transport). This is analogous to the Circulatory System in animals.
  • Epidermal Tissue: The outer protective layer of a plant, which is similar to Skin in humans.

Physics: Optics and Light

Nature of Light and Reflection

• Luminous vs. Non-luminous Objects:

  • Luminous: Objects that produce their own light (e.g., the Sun, a light bulb).
  • Non-luminous: Objects that reflect light from other sources (e.g., the Moon, a book).

• The Electromagnetic Spectrum: Visible light is only a small portion of the electromagnetic spectrum. It differs from other radiation (like X-rays or Microwaves) by its specific wavelength range ($400$ to $700$ nanometers).

• Mirrors and Reflection Coatings: Modern mirrors are typically made of glass coated with a thin layer of reflective metal, usually Aluminum ($Al$) or Silver ($Ag$).

• The Law of Reflection: The angle of incidence ($\theta_i$) is always equal to the angle of reflection ($\theta_r$) when measured from the normal line.     $\theta_i = \theta_r$

Curved Mirrors and Ray Diagrams

• Concave (Converging) Mirrors: The SALT (Size, Attitude, Location, Type) of the image changes based on the object's position relative to the Focal Point ($F$) and Center of Curvature ($C$).

  • Object at infinity: Image at $F$, point size.
  • Object beyond $C$: Smaller, inverted, between $C$ and $F$, real.
  • Object at $C$: Same size, inverted, at $C$, real.
  • Object between $C$ and $F$: Larger, inverted, beyond $C$, real.
  • Object at $F$: No image (rays are parallel).
  • Object inside $F$ (between $F$ and mirror): Larger, upright, behind mirror, virtual.

• Applications of Mirrors:

  • Concave: Used in flashlights, makeup mirrors (magnification), and dental mirrors.
  • Convex: Provide a wide field of view; used in security mirrors and passenger-side car mirrors.

Refraction and Total Internal Reflection

• Index of Refraction ($n$): A ratio of the speed of light in a vacuum ($c$) to the speed of light in a specific medium ($v$).     $n = \frac{c}{v}$

  • Where $c \approx 3.00 \times 10^8\, \text{m/s}$.
  • A substance with a higher index of refraction will bend (refract) light more toward the normal.

• Total Internal Reflection (TIR): Occurs when light travels from a more dense medium to a less dense medium and the angle of incidence is greater than the critical angle ($\theta_c$).

  • Conditions:
    1. $n_1 > n_2$ (light slows down in first medium).
    2. $\theta_i > \theta_c$.