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Study Guide - Smart Notes
Tailored notes based on your materials, expanded with key definitions, examples, and context.
Introduction to General Chemistry
Matter and Its Classification
Chemistry is the study of matter and its changes. Matter is anything that occupies space and has mass. Understanding how matter is classified is fundamental to general chemistry.
Pure Substance: Composed of only one kind of atom or molecule. Examples include gold (Au) and water (H2O).
Mixture: Contains two or more different elements or compounds physically mixed. Mixtures can be:
Homogeneous Mixture: Uniform composition throughout (e.g., salt water).
Heterogeneous Mixture: Non-uniform composition (e.g., salad, salsa).
Element: Pure substance made of one type of atom (e.g., oxygen (O2)).
Compound: Pure substance made of two or more types of atoms chemically bonded (e.g., water (H2O)).
Classification Table
Type | Definition | Example |
|---|---|---|
Element | Pure substance made of one type of atom | Oxygen (O2) |
Compound | Pure substance made of two or more types of atoms chemically bonded | Water (H2O) |
Homogeneous Mixture | Uniform composition throughout | Salt water |
Heterogeneous Mixture | Non-uniform composition | Salad |
Physical and Chemical Changes
Changes in matter can be classified as physical or chemical, depending on whether the chemical identity is altered.
Physical Changes: Alter the physical state without changing chemical composition. Examples: melting, boiling, dissolving sugar in water.
Chemical Changes: Result in new substances with new chemical bonds and properties. Examples: burning wood, cooking an egg, rusting iron.
Phase Changes: Reversible and Irreversible
Reversible Changes: Can be undone to restore the original structure (e.g., melting, freezing, boiling, dissolving sugar in water).
Irreversible Changes: Cannot be undone (e.g., burning, cooking an egg).
Phase Change Table
Phase Change | Bond Forming | Bond Breaking |
|---|---|---|
Gas to Liquid | Condensation | Evaporation |
Liquid to Solid | Freezing | Melting |
Chemical and Physical Properties
Properties of matter are used to describe and identify substances.
Chemical Properties: Observed during a chemical reaction; describe how a substance interacts with others. Examples: reactivity with acids, flammability, oxidation.
Physical Properties: Can be observed without changing chemical identity. Examples: color, melting point, density, state at room temperature.
Intensive vs. Extensive Properties
Properties are classified based on their dependence on the amount of substance present.
Intensive Properties: Do not depend on the amount present. Examples: density, melting point, color.
Extensive Properties: Depend on the size or amount present. Examples: mass, volume, length.
Property Type Table
Property Type | Examples |
|---|---|
Intensive | Density, temperature, color |
Extensive | Mass, volume, length |
SI Units and Measurements
SI Base Units
The International System of Units (SI) provides standard units for physical quantities in science.
Physical Quantity | Name | 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 |
Perimeter, Area, and Volume
Area (rectangle):
Volume (rectangular prism):
Volume (cylinder):
Metric Prefixes
Metric prefixes indicate multiples or fractions of base units.
Prefix | Symbol | Multiplier |
|---|---|---|
Kilo | k | 103 |
Milli | m | 10-3 |
Micro | μ | 10-6 |
Nano | n | 10-9 |
Centi | c | 10-2 |
Example: To convert 654 kg to g, multiply by .
Temperature and Scientific Notation
Thermal Energy: Sum of kinetic and potential energies of all atoms in an object.
Temperature: Average kinetic energy of an object.
Temperature Conversion Formulas
Celsius to Kelvin:
Celsius to Fahrenheit:
Scientific Notation
Format: where is the coefficient and is the exponent.
Example:
Significant Figures
Significant figures reflect the precision of a measurement.
All nonzero digits are significant.
Zeros between nonzero digits are significant.
Leading zeros are not significant.
Trailing zeros in a decimal number are significant.
Significant Figures in Calculations
Multiplication/Division: Result has the same number of significant figures as the measurement with the fewest significant figures.
Addition/Subtraction: Result has the same number of decimal places as the measurement with the fewest decimal places.
Conversion Factors and Dimensional Analysis
Conversion Factors
Conversion factors are ratios that relate two different units and are used to convert measurements.
Conversion | Factor |
|---|---|
Length | 1 in = 2.54 cm |
Mass | 1 kg = 1000 g |
Volume | 1 L = 1000 mL |
Time | 1 hour = 60 minutes |
Example: To convert inches to centimeters, multiply by 2.54.
Dimensional Analysis
Dimensional analysis is a systematic method for converting units using conversion factors.
Write the given amount.
Multiply by conversion factors to cancel units.
Arrive at the desired unit.
Density and Measurement
Density
Density is the amount of mass per unit volume and is a key property for identifying substances.
Formula:
Units: g/cm3 for solids and liquids, g/L for gases.
Density of Geometric Objects
Calculate volume using geometric formulas, then use density to find mass or vice versa.
Example (cube): where is the length of a side.
Density by Water Displacement
For irregular objects, volume can be measured by the amount of water displaced.
Example: If water rises from 200 mL to 265 mL, the object's volume is 65 mL.
Additional info: These notes cover foundational concepts in General Chemistry, including matter classification, physical and chemical changes, properties, measurement, SI units, scientific notation, significant figures, conversion factors, dimensional analysis, and density. Practice questions and examples are included to reinforce understanding.
