Chapter 1: Introduction – Matter & Measurement (General Chemistry Study Notes)

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Tailored notes based on your materials, expanded with key definitions, examples, and context.

Classification of Matter

Pure Substances and Mixtures

Matter is anything that occupies space and has mass. It can be classified based on its composition into pure substances and mixtures.

Pure Substance: A type of matter with a fixed composition. It can be an element (composed of one kind of atom) or a compound (composed of two or more different elements chemically bonded).
Mixture: A combination of two or more substances that are physically mixed but not chemically bonded. Mixtures can be homogeneous (uniform composition, also called solutions) or heterogeneous (non-uniform composition).

Example: Air is a homogeneous mixture; sand and iron filings are a heterogeneous mixture.

Type	Definition	Example
Element	Single type of atom	Gold (Au)
Compound	Two or more elements chemically bonded	Water (H2O)
Homogeneous Mixture	Uniform composition	Salt water
Heterogeneous Mixture	Non-uniform composition	Sand and iron filings

Physical and Chemical Changes

Physical Changes

Physical changes alter the state or appearance of matter without changing its composition.

Examples: Melting ice, dissolving sugar in water, tearing paper.

Chemical Changes

Chemical changes result in the formation of new substances with different compositions and properties.

Examples: Burning wood, cooking an egg, rusting iron.

Reversible and Irreversible Changes

Phase Changes

Phase changes (such as melting, freezing, vaporization) are typically reversible physical changes.

Bond Forming: Gas to liquid to solid
Bond Breaking: Solid to liquid to gas

Irreversible changes cannot be undone by simple physical means (e.g., burning paper).

Chemical and Physical Properties

Chemical Properties

Chemical properties describe a substance's ability to undergo chemical changes, forming new substances.

Examples: Reactivity with acids, flammability, oxidation state.

Physical Properties

Physical properties can be observed or measured without changing the substance's chemical identity.

Examples: Color, melting point, density, state (solid/liquid/gas).

Intensive vs. Extensive Properties

Intensive Properties

Intensive properties do not depend on the amount of substance present.

Examples: Density, melting point, boiling point, color.

Extensive Properties

Extensive properties depend on the amount of substance present.

Examples: Mass, volume, length.

Property Type	Depends on Amount?	Examples
Intensive	No	Density, temperature
Extensive	Yes	Mass, volume

SI Units and Measurements

SI Base Units

The International System of Units (SI) uses seven base units for physical quantities.

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

Perimeter: for a rectangle
Area: for a rectangle
Volume: for a rectangular prism

Metric Prefixes

Metric Prefix Multipliers

Metric prefixes indicate multiples or fractions of base units.

Prefix	Symbol	Multiplier
kilo	k
centi	c
milli	m
micro	μ
nano	n

Example: 654 kg = 6.54 × kg

Temperature and Temperature Conversion

Thermal Energy and Temperature

Temperature measures the average kinetic energy of particles in a substance. Thermal energy is the total kinetic and potential energy of all particles.

Temperature Conversion

Celsius to Kelvin:
Celsius to Fahrenheit:

Scientific Notation

Expressing Numbers in Scientific Notation

Scientific notation is used to write very large or small numbers in a compact form: where and is an integer.

Example: 6,800,000 =

Converting Between Standard and Scientific Notation

Move the decimal point to create a coefficient between 1 and 10, adjusting the exponent accordingly.

Significant Figures

Identifying Significant Figures

Significant figures are the digits in a measurement that are known with certainty plus one estimated digit.

Rules: All nonzero digits are significant; zeros between nonzero digits are significant; leading zeros are not significant; trailing zeros are significant only if there is a decimal point.

Significant Figures in Calculations

Multiplication/Division: The result should have the same number of significant figures as the measurement with the fewest significant figures.
Addition/Subtraction: The result should have 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 used to express a quantity in different units.

Example: 1 inch = 2.54 cm

Dimensional Analysis

Dimensional analysis is a method for converting between units using conversion factors.

Set up the calculation so that units cancel appropriately, leaving the desired unit.

Density

Definition and Formula

Density is the amount of mass per unit volume.

Formula:
Units: g/cm3 for solids and liquids; g/L for gases

Density of Geometric and Non-Geometric Objects

For regular shapes, use geometric formulas for volume.
For irregular shapes, use water displacement to determine volume.

Example: If a cube has a side length of 0.36 m and a density of 10.5 g/cm3, its mass is calculated by finding the volume and multiplying by density.

Water Displacement

Measuring Volume of Irregular Objects

Water displacement is used to measure the volume of an object by noting the change in water level when the object is submerged.

Example: If water rises from 200 mL to 265 mL, the object's volume is 65 mL.

Additional info: These notes are based on "Brown - Chemistry: The Central Science, Ch.1 - Introduction: Matter & Measurement" and cover foundational concepts for General Chemistry students, including classification of matter, properties, measurement, and basic calculations.