Material World

Matter

Particle Model States that matter exists in three primary states: solid, liquid, gas. Each state has distinct properties based on the arrangement and behavior of particles.

Atomic Structure

Atom vs. Molecule (pg. 8)

• Atom: The basic unit of matter, consisting of protons, neutrons, and electrons.

• Molecule: A group of two or more atoms bonded together.

Elements and Compounds

Element vs. Compound (pg. 21)

• Element: A pure substance that cannot be broken down further by chemical means; consists of one type of atom.

• Compound: A substance formed from two or more atoms that are chemically bonded in fixed proportions.

Periodic Table

Periodic Table (pgs. 21-22)A systematic arrangement of elements based on atomic number, electron configuration, and recurring chemical properties. Groups and periods indicate similarities in element characteristics.

Mixtures

Types of Mixtures (pgs. 10-11)

• Heterogeneous Mixtures: Mixtures that have a non-uniform composition; individual components can be seen.

• Homogeneous Mixtures: Mixtures that have a uniform composition throughout; components blend completely.

Solutions

Definitions (pg. 12)

• Solute: The substance that is dissolved in a solution.

• Solvent: The substance that does the dissolving; usually present in greater quantity.

• Solution: is a homogenous mixture in which it is impossible to distinguish its constituents parts, even under a magnifying instrument

Concentration and Dilution Calculations

Concentration Calculations (C = m/V) (pg. 13)Formula to determine the concentration of a solution, where C is concentration, m is mass of solute, and V is volume of solution.

Dilution Calculations (C1V1 = C2V2) (pgs. 15-16)Equation used to calculate the volumes and concentrations before and after dilution of a solution.

Solubility

Solubility

• Definition: Refers to the maximum amount of solute that can dissolve in a solvent at a specific temperature and pressure.

• Concentration: The amount of solute in a volume of solvent, expressed as molarity or mass percent.

Saturated Solutions: Formed when maximum solubility is reached; excess solute remains undissolved.

Factors Affecting Solubility:

• Nature of Solute and Solvent: Molecule characteristics determine solubility (e.g., ionic compounds dissolve in polar solvents).

• Temperature:

  • Gases: Increased temperature decreases solubility; pressure increases it.

  • Solids: Increased temperature generally increases solubility.

• Pressure: Affects gas solubility significantly; less impact on solids and liquids.

Dissolution Overview:

• Definition: Process of a solute dispersing in a solvent to form a solution.

• Types of Solutions:

  • Saturated: Maximum solute dissolved.

  • Unsaturated: Can dissolve more solute.

  • Supersaturated: Contains excess solute; achieved by altering conditions.

• Applications: Important in chemistry, pharmaceuticals, and food science.

Separating Mixtures

6 Techniques (pg. 20)

1. Filtration: A technique that uses a porous barrier to separate solid from a liquid. The solid remains on the filter while the liquid passes through.

2. Distillation: A separation method based on differences in boiling points. The mixture is heated until one component vaporizes, which is then cooled and condensed back into a liquid.

3. Chromatography: A technique that separates components of a mixture based on their movement through a stationary phase. Different components travel at different rates, allowing separation.

4. Sublimation: The process in which a solid changes directly into gas without passing through a liquid state. Used to separate substances that can sublime from those that cannot.

5. Centrifugation: The method involves spinning a mixture at high speeds to separate components based on density. Heavier components move outward while lighter ones stay closer to the center.

6. Evaporation: The process of turning liquid into vapor. This technique is used to separate a soluble solid from a liquid by evaporating the liquid, leaving the solid behind.

Pure Substances

Characteristics of Pure Substances (pgs. 21-26)

• Compounds: Must be chemically combined and can only be separated into their components by chemical reactions.

• Elements: Individual atoms classified by atomic number.

• Properties: Characteristic properties used to identify and categorize substances. Physical Properties of Matter

  Physical properties are characteristics that can be observed or measured without changing the substance’s chemical identity. These properties include:

• Physical Properties of Matter

  • Color: The visual appearance of a substance, which can vary widely among different substances.

  • Density: The mass of a substance per unit volume, which helps to determine whether it will float or sink in a fluid.

  • Mass: The amount of matter in an object, usually measured in grams or kilograms.

  • Volume: The amount of space occupied by a substance, commonly measured in liters or cubic centimeters.

  • Melting Point: The temperature at which a solid becomes a liquid; this is a unique property for each substance.

  • Boiling Point: The temperature at which a liquid becomes a gas; like melting points, this varies across substances.

  • Solubility: The ability of a substance to dissolve in a solvent, measured typically in terms of concentration.

  • State of Matter: Refers to whether a substance is a solid, liquid, or gas based on temperature and pressure conditions.

  • Conductivity: The ability of a substance to conduct electricity or heat, a crucial aspect in materials used for electrical applications.

  • Characteristic Chemical Properties of Matter

    Chemical properties describe how a substance interacts with others and change its chemical identity in the process. These properties include:

    Introduction to Chemical Indicators

    • Chemical indicators are substances that change color or properties in response to different conditions, and they are commonly used in testing the acidity of solutions and in various fields including medicine and nutrition.

    Testing for Acidity with Litmus Paper

    • Litmus Paper Reaction

      • Red color indicates an acidic solution (pH < 7).

      • Blue color indicates a basic solution (pH > 7).

      • Purple color indicates a neutral solution (pH = 7).

    Indicators for Water Detection

    • Cobalt Chloride Paper Reaction

      • Pink color indicates the presence of water in the test substance.

      • Different shades of blue indicate varying amounts of moisture.

    Detecting Carbon Dioxide

    • Limewater Reaction

      • A milky appearance indicates the presence of carbon dioxide gas.

      • A precipitate formation further confirms this reaction.

    Testing for Combustible Substances

    • Glowing Wood Splint Reaction

      • If the splint reignites, oxygen gas is present in the test substance.

    Detecting Explosive Gases

    • Burning Wood Splint Reaction

      • The occurrence of an explosion indicates the presence of an explosive gas, such as hydrogen.

    Identification of Elements through Flame Tests

    • Open Flame Reaction

      • Color changes in the flame can indicate the presence of specific elements:

        • Purple flame: Potassium

        • Green flame: Barium

        • Red flame: Strontium

    Summary of Characteristic Chemical Properties of Matter

    • Various chemical tests provide insights into the properties of substances, making them essential in laboratories for identifying components and testing reactions.

Energy

Four Types of Energy (pgs. 36-40)Different forms of energy include kinetic, potential, thermal, and chemical energy. Each form can transform from one type to another.

• Kinetic Energy: The energy possessed by an object due to its motion. It depends on the mass of the object and the square of its velocity, and can be calculated using the formula: KE = 1/2 mv², where KE is kinetic energy, m is mass, and v is velocity.

• Potential Energy: The energy stored in an object due to its position or condition. It is often associated with gravitational force; for example, an object raised to a certain height has gravitational potential energy, which can be calculated using: PE = mgh, where PE is potential energy, m is mass, g is the acceleration due to gravity, and h is height.

• Thermal Energy: The total kinetic and potential energy of the particles in an object, often perceived as heat. Thermal energy increases with the temperature of the object and plays a crucial role in determining the state of matter (solid, liquid, gas) based on temperature.

• Chemical Energy: The energy stored in the bonds of chemical compounds. This energy is released or absorbed during a chemical reaction, making it a critical form of energy in biological processes and industrial applications. The potential energy contained in chemical bonds can be converted to other forms of energy, such as thermal energy, when substances react chemically.

Energy Transfer vs. Transformation

Transfer vs. Transformation (pgs. 41-42)

• Energy Transfer: Movement of energy from one object or system to another.

• Energy Transformation: Change of energy from one form to another within a system.

Changes in Matter

Physical Changes (pgs. 43-50) Involves changes in state (e.g., solid to liquid), dissolution (such as salt in water), and deformation (bending or breaking).

Chemical Changes (pgs. 50-52) Identified by five indicators such as color change, temperature change, gas production, formation of a precipitate, and change in properties.

Chemical Reactions

4 Important Chemical Reactions (pgs. 53-58)

1. Synthesis Reaction: Two or more reactants combine to form a single product. An example includes the formation of water from hydrogen and oxygen.

2. Decomposition Reaction: A single compound breaks down into two or more simpler products. For instance, the decomposition of water into hydrogen and oxygen gas.

3. Oxidation Reaction: This is a type of chemical reaction where a substance loses electrons, resulting in an increase in its oxidation state. Oxidation often occurs in conjunction with reduction, where another substance gains the electrons that the oxidated substance has lost. Common examples include rusting of iron or combustion of organic materials.

4. Precipitation Reaction: A precipitation reaction occurs when two soluble salts react in a solution to form an insoluble compound, known as a precipitate. This precipitate separates from the solution, usually visible as a solid. An example of a precipitation reaction is the formation of barium sulfate when barium chloride and sodium sulfate are mixed in solution. This solid precipitate can be filtered out from the liquid phase, demonstrating the distinct separation of products in chemical reactions.