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Chapter 1: Matter, Measurements, and Problem Solving – General Chemistry Study Notes

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Chapter 1: Matter, Measurements, and Problem Solving

Chemistry: The Study of Matter and Its Changes

Chemistry is the scientific discipline concerned with the study of matter, its properties, and the changes it undergoes. Matter exists in different states and can transform through physical and chemical processes.

  • Matter is anything that occupies space and has mass.

  • Atoms are the fundamental building blocks of matter.

  • Elements consist of only one kind of atom.

  • Molecules are composed of two or more atoms bonded together.

  • Compounds are substances made of two or more different elements in fixed proportions.

  • Example: Water (H2O) is a compound made of hydrogen and oxygen atoms.

The Scientific Approach to Knowledge

The scientific method is a systematic process for acquiring knowledge about nature through observation, hypothesis formation, experimentation, and the development of laws and theories.

  • Observation: Gathering data about the characteristics or behavior of nature.

  • Hypothesis: A tentative explanation for observations; must be falsifiable.

  • Experimentation: Testing hypotheses through controlled procedures.

  • Law: A concise statement summarizing past observations and predicting future ones (e.g., Law of Conservation of Mass: "In a chemical reaction, matter is neither created nor destroyed.").

  • Theory: A well-substantiated explanation of some aspect of nature, validated by experiments (e.g., Dalton’s atomic theory).

Classification of Matter

Matter can be classified by its physical state and composition.

  • States of Matter:

    • Gas: Particles are far apart, have high freedom of motion, and fill the container.

    • Liquid: Particles are closer together, can move past each other, and take the shape of the container.

    • Solid: Particles are closely packed; may be crystalline (ordered, repeating pattern, e.g., diamond) or amorphous (no long-range order, e.g., glass).

  • Classification by Composition:

    • Pure Substance: Composed of only one component; composition is invariant.

    • Mixture: Composed of two or more components; composition can vary.

  • Types of Pure Substances:

    • Element: Cannot be chemically broken down into simpler substances.

    • Compound: Composed of two or more elements in fixed proportions.

  • Types of Mixtures:

    • Heterogeneous Mixture: Composition varies from one region to another (e.g., sand and salt mixture).

    • Homogeneous Mixture: Uniform composition throughout (e.g., sweetened tea).

Separating Mixtures

Mixtures can be separated by exploiting differences in physical or chemical properties.

  • Decanting: Pouring off liquid from a solid-liquid mixture.

  • Distillation: Separates components based on differences in boiling points.

  • Filtration: Separates solids from liquids using a filter.

  • Chromatography: Separates substances based on differences in solubility.

Types of Properties

  • Physical Properties: Can be observed without changing the substance (e.g., boiling point, density).

  • Chemical Properties: Can only be observed when the substance changes into another (e.g., flammability, reactivity).

  • Intensive Properties: Independent of the amount of substance (e.g., density, color).

  • Extensive Properties: Depend on the amount of substance (e.g., mass, volume).

Types of Changes

  • Physical Changes: Do not alter the composition of the substance (e.g., melting, boiling).

  • Chemical Changes: Result in new substances (e.g., combustion, rusting).

  • Example: Rusting of iron is a chemical change:

Energy in Physical and Chemical Changes

Energy is a fundamental concept in chemistry, associated with the capacity to do work.

  • Kinetic Energy: Energy due to motion.

  • Potential Energy: Energy due to position or composition.

  • Thermal Energy: Energy associated with temperature; a form of kinetic energy.

  • Law of Conservation of Energy: Energy is neither created nor destroyed in physical or chemical changes.

The Units of Measurement

Chemistry relies on standardized units for measurement. The International System of Units (SI) is the standard system used by scientists.

  • Metric System: Used globally.

  • English System: Used in the United States.

  • SI Base Units:

    Quantity

    Unit

    Symbol

    Length

    Meter

    m

    Mass

    Kilogram

    kg

    Time

    Second

    s

    Temperature

    Kelvin

    K

    Amount of substance

    Mole

    mol

    Electric current

    Ampere

    A

    Luminous intensity

    Candela

    cd

Measurement Units and Conversions

  • Length: Meter (m); 1 m = 39.37 inches.

  • Mass: Kilogram (kg); 1 kg = 2.205 lb. Gram (g) is 1/1000 kg.

  • Time: Second (s); defined by cesium-133 atom transitions.

  • Temperature: Kelvin (K); absolute zero is 0 K ().

  • Temperature Conversion Formulas:

Practice Example

  • Convert 120.0 °F into Kelvin:

    • First, convert °F to °C:

    • Then, convert °C to K: K

*Additional info: These notes are based on textbook-style lecture slides and provide foundational concepts for General Chemistry Chapter 1, including matter, measurement, scientific method, classification, and units of measurement.*

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