Science Test Study - Chemistry Notes PDF

**Matter:** Matter is anything that has mass and occupies space. It can exist in three primary states: solid, liquid, and gas. Matter is made up of atoms, which are the basic units of elements. **Elements:** An element is a pure substance made of one type of atom. Elements are organized in the pe...

**Matter:** Matter is anything that has mass and occupies space. It can exist in three primary states: solid, liquid, and gas. Matter is made up of atoms, which are the basic units of elements. **Elements:** An element is a pure substance made of one type of atom. Elements are organized in the periodic table. They can be classified as: - **Monatomic Elements**: These are elements that consist of single atoms. Examples include noble gases like helium (He) and argon (Ar). - **Diatomic Elements**: These are elements that exist as pairs of atoms. Examples include hydrogen (H₂), oxygen (O₂), and nitrogen (N₂). - **Polyatomic Elements**: These consist of more than two atoms. Examples include phosphorus (P₄) and sulfur (S₈). **Compounds:** A compound is a substance formed when two or more elements chemically bond together. Compounds can be classified as: - **Ionic Compounds**: These are made up of positively charged ions (cations) and negatively charged ions (anions) that are held together by ionic bonds. Common ionic compounds include sodium chloride (NaCl) and magnesium oxide (MgO). - **Molecular Compounds**: These are made up of atoms held together by covalent bonds, where atoms share electrons. Examples include water (H₂O) and carbon dioxide (CO₂). **Ionic Bonds:** Ionic bonds occur when electrons are transferred from one atom to another, resulting in the formation of oppositely charged ions that attract each other. This bond typically forms between metals and nonmetals. Ionic compounds tend to have high melting and boiling points. **Molecular Compounds:** Molecular compounds are formed when atoms share electrons through covalent bonds. These compounds can be gases, liquids, or solids. Examples include carbon monoxide (CO) and methane (CH₄). **Mixtures:** A mixture is a combination of two or more substances that are not chemically bonded. Mixtures can be: - **Heterogeneous**: The components are not uniformly distributed, and different parts of the mixture can be seen. Examples include a salad or soil. - **Homogeneous**: The components are uniformly distributed, and it appears as a single substance. Examples include air or saltwater. **Cations and Anions:** - **Cations** are positively charged ions, formed when an atom loses one or more electrons. For example, Na⁺ (sodium ion). - **Anions** are negatively charged ions, formed when an atom gains one or more electrons. For example, Cl⁻ (chloride ion). **Polyatomic Ions:** These are ions composed of more than one atom. Common examples include sulfate (SO₄²⁻), nitrate (NO₃⁻), and ammonium (NH₄⁺). **Properties of Covalent Compounds:** - Generally, have low melting and boiling points. - Do not conduct electricity because they do not produce ions in solution. - Usually, they are soluble in nonpolar solvents and insoluble in water. **Properties of Ionic Compounds:** - High melting and boiling points. - Conduct electricity when dissolved in water or molten because they produce free-moving ions. - Tend to be brittle. **Ionic Compounds Conduct Electricity:** When ionic compounds dissolve in water or are melted, their ions are free to move, allowing the compound to conduct electricity. This property is the reason electrolytes (which are often ionic compounds) are used in batteries and other electrical devices. **Ionic Bonds are Strong:** Ionic bonds are typically strong due to the electrostatic attraction between the positive and negatively charged ions. This strength leads to the high melting and boiling points of ionic compounds. **Balancing Chemical Equations:** In a chemical reaction, the total number of atoms on both sides of the equation must be the same to follow the **Law of Conservation of Mass**, which says that matter cannot be created or destroyed in a chemical reaction. - **Subscripts** show the number of atoms of each element in a molecule (e.g., H₂O). - **Coefficients** show how many molecules or moles of a substance engage in the reaction (e.g., 2H₂O means two molecules of water). **Chemical Reaction Formulas:** There are several types of chemical reactions: - **Synthesis**: Two or more simple substances combined to form a more complex substance. Example: A + B → AB. - **Decomposition**: A complex substance breaks down into simpler substances. Example: AB → A + B. - **Single Displacement**: One element replaces another in a compound. Example: A + BC → AC + B. - **Double Displacement**: The cations and anions of two ionic compounds exchange places to form new compounds. Example: AB + CD → AD + CB. - **Combustion**: A substance reacts with oxygen, releasing energy in the form of heat and light. Example: CH₄ + 2O₂ → CO₂ + 2H₂O. **Acids and Bases:** - **Acids** are substances that release hydrogen ions (H⁺) when dissolved in water. Examples include hydrochloric acid (HCl) and sulfuric acid (H₂SO₄). - **Bases** are substances that release hydroxide ions (OH⁻) when dissolved in water. Examples include sodium hydroxide (NaOH) and potassium hydroxide (KOH). **Acid-Base Indicators:** Indicators are substances that change color depending on the pH of the solution. Common indicators include litmus paper (which turns red in acidic solutions and blue in basic solutions) and phenolphthalein (which turns pink in basic solutions). **pH Scale:** The pH scale measures the acidity or basicity of a solution. It ranges from 0 to 14: - A pH less than 7 is acidic. - A pH of 7 is neutral (pure water). - A pH greater than 7 is basic. **Neutralization:** Neutralization is a chemical reaction between an acid and a base to produce water and salt. Example: HCl + NaOH → NaCl + H₂O. This reaction results in a neutral solution with a pH of 7. **Ecology** **Ecology is the study of the interactions between living organisms and their environment, focusing on the distribution and abundance of organisms and the processes that govern these patterns. It involves understanding ecosystems, biomes, trophic levels, energy transfer, and other complex interactions like biotic and abiotic factors, biomagnification, and more.** **Biomes** **A biome is a large geographic biotic unit, characterized by a specific climate, vegetation, and animal life. Examples of major biomes include:** - **Tropical Rainforests: Hot and humid, high biodiversity.** - **Deserts: Dry, with specialized plant and animal life.** - **Temperate Forests: Moderate climate, deciduous trees.** - **Tundra: Cold, with permafrost and limited vegetation.** - **Savannas: Grasslands with sparse trees, often subject to wildfires.** - **Aquatic Biomes: Freshwater and marine ecosystems.** **Trophic Levels and Energy Transfer** **Energy flows through an ecosystem in a pyramid shape, with each level representing a step in the food chain. This is the trophic pyramid:** 1. **Producers (Autotrophs): Plants and algae that photosynthesize, capturing energy from the sun.** - **Energy Transfer: 100% of the energy starts here.** - **Species: A large number of species.** 2. **Primary Consumers (Herbivores): Organisms that eat producers.** - **Energy Transfer: Around 10% of energy is passed to herbivores.** - **Species: Many species, often smaller.** 3. **Secondary Consumers (Carnivores): Animals that eat herbivores.** - **Energy Transfer: Around 1% of the energy is passed on to secondary consumers.** - **Species: Fewer species compared to primary consumers.** 4. **Tertiary Consumers (Top Carnivores): Organisms at the top of the food chain, often apex predators.** - **Energy Transfer: Less than 0.1% of the energy is passed to top predators.** - **Species: Fewest species.** **The total energy decreases as it moves up the trophic pyramid due to the Second Law of Thermodynamics, with energy being lost as heat at each level.** Trophic level Diagram - Ecological Pyramids **Biomagnification** **Biomagnification refers to the increasing concentration of toxins in organisms at higher trophic levels. For instance, pollutants like mercury or DDT accumulate in organisms over time. At each step up the food chain, the concentration of these toxins magnifies, causing harm to top predators (like bald eagles, sharks, or humans). It often results in reproductive failure or death in sensitive species.** **Limiting Factors & Carrying Capacity** **In an ecosystem, limiting factors are conditions that restrict the growth or survival of organisms, such as:** - **Density-Dependent Factors: These include factors like food availability, predation, disease, and competition. The effects of these factors increase as the population density increases.** - **Density-Independent Factors: These include environmental factors like natural disasters, temperature extremes, or habitat destruction, which impact populations regardless of their density.** **Carrying Capacity is the maximum population size an environment can support given its resources, and it is determined by these limiting factors.** **Trophic Cascades** **A trophic cascade occurs when a top predator influences the population size of species at lower trophic levels, leading to cascading effects through the ecosystem. For instance, the absence or removal of wolves can cause an increase in the moose population, which may lead to overgrazing and depletion of vegetation, affecting the entire ecosystem.** **Isle Royale Wolves and Moose** **Isle Royale is a natural laboratory for studying predator-prey dynamics, particularly between wolves (the predators) and moose (the prey). This balance has been heavily studied, especially after observing how the removal of wolves leads to moose population booms, resulting in ecological damage (e.g., over browsing of vegetation).** **You can explore this graph and research on the Isle Royale Wolf and Moose dynamics.**  **Biodiversity** **Biodiversity refers to the variety of life on Earth, including diversity within species, between species, and across ecosystems. Maintaining high biodiversity is critical to ecosystem stability and resilience. In this video, Biodiversity and Ecosystem Functioning, it explains how biodiversity is essential to ecosystem health and how species interact to maintain ecological balance: [Watch Video on Biodiversity](https://www.youtube.com/watch?v=rXJ3vmOWATk).** **Biotic and Abiotic Factors** - **Biotic factors include all the living components of an ecosystem, such as plants, animals, fungi, and bacteria.** - **Abiotic factors are the non-living physical and chemical components, such as sunlight, water, temperature, soil, and air.** **Bioaccumulation** **Bioaccumulation refers to the gradual buildup of toxins in an organism's body over time. Unlike biomagnification, which occurs as you move up the food chain, bioaccumulation occurs within a single organism, often because the organism absorbs more of the toxin than it can excrete.** **Japanese Knotweed** Description: - Japanese knotweed stems are hollow, smooth, purple to green colored, and up to 2.5 cm in diameter. They die back each fall, and new stems emerge in the spring. - Japanese knotweed can grow up to 1 m in three weeks and can reach heights of 1-3 m (3-10 ft). - Japanese knotweed has small, white-green flowers in late July or August that are produced in branching panicles (clusters). The seeds are winged, triangular, shiny, and exceedingly small. - Japanese knotweed is found across southern, central, and eastern Ontario with isolated populations in Winnipeg, Manitoba, and southern British Columbia. - As the climate warms, Japanese knotweed may be able to spread further north. Road maintenance, forestry operations, and construction activities may spread these plants further. - Japanese knotweed can severely degrade the quality of wetland and riparian habitats where it becomes established and may have allelopathic properties that alter soil chemistry or prohibit the growth of nearby native species. - Japanese knotweed roots do not hold soil as well as native plants and can cause stream banks to become unstable and more vulnerable to erosion and flooding. - Japanese knotweed is a semi-woody perennial plant that is aggressive and can spread 10 meters (32.8 feet) from the parent stem and grow through concrete and asphalt. - In Canada, Japanese knotweed is found from Ontario to Newfoundland and Labrador and in British Columbia. - Japanese Knotweed is a semi-woody perennial plant that reaches 1-3 m (3.3-9.8 ft) in height. It has round, reddish purple, smooth stems, and ovate leaves with pointed tips. Origin: - The earliest recording of Japanese knotweed arriving in North America was in the 1800s. Its flowers and height were attractive to those looking for dense coverage along the roadsides. Japanese knotweed is native to Asian countries, primarily Japan, China, Korea, and Taiwan. It is currently one of the most invasive plants in the world and is thought to be found on every continent besides Antarctica. Here's a detailed breakdown of motion concepts, including all the requested topics, formulas, and examples: **1. Origin and Position** - **Origin:** A fixed reference point from which positions are measured. It is often represented as x =0 in 1D motion. - **Position (x):** The location of an object relative to its origin. It is a vector quantity with magnitude and direction. - Example: If an object is 5 m to the right of the origin, x=+5 m. **2. Scalars and Vectors** - **Scalar:** A quantity with only magnitude (e.g., speed, time, mass). - **Vector:** A quantity with magnitude and direction (e.g., velocity, displacement, force). **3. Time Interval (Δt)** - **Definition:** The difference between two instances. - Formula: Δt=t2−t1 - Example: If an event starts at t1=2 s and ends at t2=5 s, then Δt=5−2=3s **4. Displacement (Δx)** - **Definition:** The change in position of an object. - Formula: Δx=x2−x1 - Example: If an object moves from x1=2 mx\_1 = 2 m to x2=7 m, Δx=7−2=+5 m. MECHANICS (MOTION) / DISTANCE / DISPLACEMENT- TIME GRAPHS \...  **5. Speed** - **Definition:** The rate of change of distance with respect to time. It is a scalar. - Formula: Speed=Distance/Time - Example: If an object travels 10 m in 2 s, Speed=10/2=5 m/s. **6. Velocity (v)** - **Definition:** The rate of change of displacement with respect to time. It is a vector. - Formula: v=Δx/Δt ​ - Example: If Δx=20 m and Δt=4 s, then v=20/4=5 m/s. Velocity-Time Graphs Questions \| Worksheets and Revision \| MME **7. Momentum (p)** - **Definition:** The product of an object's mass and velocity. It is a vector. - Formula: p=mv - Example: A 2 kg object moving at 3 m/s: p=2×3=6 kg/m/s. **8. Acceleration (a)** - **Definition:** The rate of change of velocity with respect to time. It is a vector. - Formula: a=Δv/Δt - Example: If Δv=10 m/s and Δt=2 s, a=10/2=5 m/s2. **9. Types of Forces** 1. **Gravity (Fg​):** The force due to gravitational attraction. - Formula: Fg=mg, where g=9.8 m/s2. - Example: A 5 kg object: Fg=5×9.8=49N. 2. **Normal Force (FN ​):** The force exerted perpendicular to the surface. 3. **Applied Force (FA ​):** The force applied to an object by an external source. 4. **Friction (Ff ​):** The resistive force opposing motion. 5. **Net Force (Fnet​):** The vector sum of all forces acting on an object. - Formula: Fnet=∑F **10. Newton's Laws of Motion** 1. **First Law (Inertia):** An object remains at rest or in uniform motion unless acted upon by a net external force. - Example: A book stays on a table unless pushed. 2. **Second Law:** The net force on an object is equal to the product of its mass and acceleration. - Formula: Fnet=ma - Example: A 3 kg object accelerating at 2 m/s2: Fnet=3×2=6N. 3. **Third Law:** For every action, there is an equal and opposite reaction. - Example: A swimmer pushes water backward and moves forward. **11. Impulse (JJJ)** - **Definition:** The change in momentum due to a force applied over a time interval. - Formula: J=FΔt=Δp - Example: A force of 10 N applied for 2 s: J=10 × 2=20N/s. **12. Change in Momentum (Δp)** - **Formula:** Δp=mΔv - Example: A 4 kg object increases its velocity from 2 m/s to 6m/s: - Δp=4 × (6−2) =16 kg/m/s.