General Chemistry I Study Guide

Chemistry Definition: Chemistry is defined as the study of matter and the changes it undergoes.

Matter: Substance that has mass and occupies space. It can be classified into two main categories:
- Mixtures:
- Definition: Combinations of two or more substances where each retains its distinct identity.
- Types:
  - Homogeneous Mixtures: Composition is uniform throughout (e.g., air, sugar water).
  - Example: Saltwater is considered a homogeneous mixture because the salt is evenly distributed throughout the water.
  - Heterogeneous Mixtures: Composition is not uniform throughout (e.g., salad, oil and vinegar dressing).
  - Example: Oil and vinegar salad dressing is a heterogeneous mixture because its composition varies.
- Pure Substances:
- Definition: A form of matter with a definite composition and distinct properties.
- Types:
  - Compounds:
  - Substances composed of atoms of two or more elements chemically united in fixed proportions (e.g., water - H₂O, sodium chloride - NaCl).
  - Cannot be separated into simpler substances by physical methods.
  - Elements:
  - Substances that cannot be separated into simpler substances by chemical means.
  - Examples include gold (Au), hydrogen (H), oxygen (O).

Health and Medicine:
- Examples include vaccinations, pharmaceuticals, and surgeries involving anesthesia.
Energy and the Environment:
- Important topics include fossil fuels, solar energy, and nuclear energy.
Food and Agriculture:
- Topics include genetically modified crops, natural pesticides, and specialized fertilizers.
Materials and Technology:
- Innovations such as polymers, ceramics, nanotechnology, and superconductors.

Three Common States:
- Solid (e.g., ice - H₂O(s)): has a defined shape and volume.
- Liquid (e.g., water - H₂O(l)): has a defined volume but takes the shape of its container.
- Gas (e.g., water vapor - H₂O(g)): has neither a defined shape nor a defined volume.

Physical Change:
- Does not alter the chemical composition of a substance.
- Examples: Melting of ice, dissolving sugar in water.
Chemical Change:
- Alters the chemical composition of the substances involved.
- Examples: Rusting of iron, combustion of natural gas.
- Questions for Understanding:
- a) Helium gas leaking from a balloon - Physical Change
- b) Flashlight dimming - Chemical Change
- c) Reconstituting frozen orange juice with water - Physical Change
- d) Photosynthesis in plants - Chemical Change
- e) Epsom salt dissolving in water - Physical Change
- f) Yeast metabolizing sugars - Chemical Change

Physical Properties:
- Can be observed without changing the identity of a substance.
- Examples:
- Melting point
- Color
- Electrical conductivity
- Flammability
- Toxicity
- Stability
Chemical Properties:
- Observed as a substance undergoes a change in its composition.
- Examples:
- Rusting of iron
- Flammability of gasoline
Distinctions:
- Chemical Property Examples: Oxygen supporting combustion, rust forming on iron.
- Physical Property Examples: Water boiling at below 100 °C at high altitude, lead's density compared to aluminum.

Extensive Properties:
- Depend on the amount of matter present.
- Examples: Mass, volume.
Intensive Properties:
- Do not depend on the amount of matter present.
- Examples: Density, temperature, color.
Classification Examples:
- A) Volume: Extensive
- B) Temperature: Intensive
- C) Density: Intensive
- D) Mass: Extensive
- E) Boiling Point: Intensive

Definition: A table displayed in columns (groups) and rows (periods) that organizes all known elements by their atomic structure.
- Each element is listed with its atomic number, symbol, and atomic mass.
Elements Identification:
- 118 elements identified, 94 found naturally on Earth.
- Natural elements include oxygen, sulfur, carbon, lead, and mining example elements such as gold and aluminum, and man-made elements like technetium and americium.

Elements in Earth's Crust:
- Oxygen (45.5%), Silicon (27.2%), Aluminum (8.3%), Iron (6.2%), Calcium (4.7%), Magnesium (2.8%), and others (5.3%).
- Earth's Structure:
- Crust: 0-5% various elements.
- Mantle: more concentrated heavier elements.
- Core: primarily iron and nickel.
Elements in the Human Body:
- Elemental breakdown: Oxygen (65%), Carbon (18%), Hydrogen (10%), Nitrogen (3%), Calcium (1.6%), Phosphorus (1.2%).

Definition: A compound is a substance composed of two or more different elements that are chemically bound together.
Separation: Can only be separated into their components by chemical means.
Examples of Compounds:
- Sodium chloride (NaCl), water (H₂O), carbon dioxide (CO₂).
- Notable Point: Even if mixed, their properties differ from the individual components.

Definition: Combinations of two or more substances in which the identities of the substances are unchanged.
Types of Mixtures:
- Homogeneous Mixtures: Composition is uniform throughout the mixture (e.g., sports drink).
- The individual components cannot be distinguished.
- Heterogeneous Mixtures: Composition varies; individual components can be seen (e.g., chicken noodle soup).
Separation Techniques: Mixtures can be separated into individual components by physical means (e.g., filtration, distillation).
Classification Examples:
- a) Well water: Homogeneous mixture
- b) Argon gas: Element
- c) Maltose: Compound
- d) Red wine: Homogeneous mixture
- e) Chicken noodle soup: Heterogeneous mixture
- f) Blood: Heterogeneous mixture
- g) Baking soda: Compound

Key takeaway: Understanding matter's properties and changes is essential in chemistry; encompassing classifications, applications, and behaviors.
Diagrams and figures, such as The Periodic Table or states of matter, visually represent essential concepts for easy comprehension.