Chapter 1: Introduction to Matter, Energy, and Measurement

Chemistry: The Central Science

Chemistry is the study of the properties, composition, and behavior of matter. It is fundamental to understanding many scientific fields, including energy, biochemistry, technology, and medicine.

• Matter is anything that has mass and occupies space.

• Chemistry connects to diverse areas such as solar energy, medical devices, biochemistry, and technology.

• Atoms are the basic building blocks of matter.

Classification of Matter

Matter can be classified based on its physical state and composition. Understanding these classifications is essential for studying chemical properties and reactions.

• States of Matter: Solid, liquid, and gas.

• Composition: Matter can be an element, compound, or mixture.

• Elements: Substances made of only one kind of atom.

• Compounds: Substances made of two or more different kinds of atoms chemically bonded.

• Mixtures: Physical combinations of two or more substances.

States of Matter

The three primary states of matter are solid, liquid, and gas. Water is a common example used to illustrate these states.

• Solid: Definite shape and volume (e.g., ice).

• Liquid: Definite volume, indefinite shape (e.g., liquid water).

• Gas: Indefinite shape and volume (e.g., water vapor).

Classification of Matter Based on Composition

Matter can be further classified as pure substances or mixtures. Pure substances have a fixed composition, while mixtures can vary.

• Pure Substance: Has distinct properties and a composition that does not vary from sample to sample.

• Element: Cannot be decomposed into simpler substances.

• Compound: Can be decomposed into simpler substances; follows the Law of Constant Composition.

• Mixture: Can be homogeneous (solution) or heterogeneous.

Physical and Chemical Properties

Properties of matter are categorized as physical or chemical, and as intensive or extensive.

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

• Chemical Properties: Observed when a substance changes into another (e.g., flammability).

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

• Extensive Properties: Dependent on the amount (e.g., mass, volume).

Physical and Chemical Changes

Changes in matter are classified as physical or chemical. Physical changes do not alter the composition, while chemical changes result in new substances.

• Physical Changes: Changes of state, temperature, or volume.

• Chemical Changes: Combustion, oxidation, decomposition.

• Converting between states of matter is a physical change.

Separation of Mixtures

Mixtures can be separated using physical methods based on differences in properties.

• Filtration: Separates solids from liquids.

• Distillation: Separates substances based on boiling points.

• Chromatography: Separates substances based on their ability to adhere to a solid surface.

Measurement in Chemistry

Quantitative measurements are essential in chemistry. The International System of Units (SI) is used for consistency.

• SI Base Units: Each physical quantity has a specific unit.

• Metric System: Uses prefixes to denote multiples or fractions of base units.

Mass, Length, and Volume

Mass and length are fundamental measurements in science. Volume is derived from length and commonly measured in liters or milliliters.

• Mass: Measured in kilograms (SI) or grams (metric).

• Length: Measured in meters.

• Volume: ; 1 dm3 = 1 L, 1 cm3 = 1 mL.

Temperature Scales

Temperature is a measure of the hotness or coldness of an object and determines the direction of heat flow. The Celsius and Kelvin scales are most commonly used in scientific measurements.

• Celsius: 0°C (water freezes), 100°C (water boils).

• Kelvin: SI unit; absolute zero is 0 K.

• Conversion:

• Fahrenheit: Not used in scientific measurements; ;

Density

Density is a physical property defined as mass per unit volume. It is commonly measured in g/mL or g/cm3.

• Formula:

• Used to identify substances and calculate mass or volume.

Numbers in Science: Accuracy, Precision, and Significant Figures

Measurements in science involve uncertainty. Accuracy and precision are important concepts, and significant figures indicate the reliability of measured values.

• Accuracy: Closeness to the true value.

• Precision: Closeness of repeated measurements to each other.

• Significant Figures: Digits that reflect the precision of a measurement.

• Rules for significant figures:

  • All nonzero digits are significant.

  • Zeroes between significant digits are significant.

  • Leading zeroes are not significant.

  • Trailing zeroes are significant if a decimal point is present.

• Rounding rules:

  • Addition/Subtraction: Round to the least significant decimal place.

  • Multiplication/Division: Round to the least number of significant figures.

Dimensional Analysis

Dimensional analysis is used to convert one unit to another using conversion factors. It is essential for solving quantitative problems in chemistry.

• Conversion Factor: A ratio expressing the equivalence between two units (e.g., 1 in = 2.54 cm).

• Set up the ratio so that units cancel appropriately.

• Example: To convert 10 inches to centimeters, use