Chapter 1: Matter, Energy, and Measurement – Foundations of General Chemistry

Chapter 1: Matter, Energy, and Measurement

Introduction to Chemistry

Chemistry is the study of matter, its properties, and the changes it undergoes. Understanding chemical principles is essential for explaining phenomena in everyday life, from food preparation to environmental processes. The properties of substances can be tailored for specific applications by controlling their composition and structure.

Matter and Its Classification

Homogeneous vs. Heterogeneous Mixtures

• Homogeneous mixture: A mixture with a uniform composition throughout. Also called a solution. Example: Saltwater.

• Heterogeneous mixture: A mixture with visibly different parts or phases. Example: Salad, oil and water.

Compound vs. Element

• Element: A pure substance that cannot be broken down into simpler substances by chemical means. Example: Oxygen (O2), Gold (Au).

• Compound: A substance composed of two or more elements chemically combined in fixed proportions. Example: Water (H2O).

Physical vs. Chemical Properties

• Physical property: A characteristic that can be observed or measured without changing the substance's identity. Examples: Color, melting point, density.

• Chemical property: A characteristic that describes a substance's ability to undergo a specific chemical change. Examples: Flammability, reactivity with acid.

Measurement in Chemistry

Numbers and Units

• Every measurement consists of a number and a unit.

• The number alone is meaningless without the unit. Example: 325 (mg or kg?)

SI Units and Metric System

The International System of Units (SI) is the standard system of measurement in science. There are seven base SI units:

Physical Quantity	Name of Unit	Abbreviation
Mass	Kilogram	kg
Length	Meter	m
Time	Second	s
Temperature	Kelvin	K
Amount of substance	Mole	mol
Electric current	Ampere	A
Luminous intensity	Candela	cd

Other commonly used units include:

• Mass: gram (g)

• Volume: liter (L), cubic centimeter (cm3 or cc)

• Temperature: degrees Celsius (°C) or Kelvin (K)

Metric Prefixes

Prefixes are used to indicate multiples or fractions of base units. Here are common metric prefixes:

Prefix	Abbreviation	Factor	Example
giga	G	109	1 gigameter (Gm) = 1 × 109 m
mega	M	106	1 megameter (Mm) = 1 × 106 m
kilo	k	103	1 kilometer (km) = 1 × 103 m
deci	d	10-1	1 decimeter (dm) = 0.1 m
centi	c	10-2	1 centimeter (cm) = 0.01 m
milli	m	10-3	1 millimeter (mm) = 0.001 m
micro	μ	10-6	1 micrometer (μm) = 1 × 10-6 m
nano	n	10-9	1 nanometer (nm) = 1 × 10-9 m
pico	p	10-12	1 picometer (pm) = 1 × 10-12 m
femto	f	10-15	1 femtometer (fm) = 1 × 10-15 m

Temperature Scales

• Celsius (°C): Based on water's properties. 0°C = freezing point, 100°C = boiling point.

• Kelvin (K): SI unit for temperature. No negative values; 0 K is absolute zero.

Conversion formulas:

• $K = ^\circ C + 273.15$

• $^\circ C = K - 273.15$

Note: The size of one degree is the same on both the Celsius and Kelvin scales; only the zero point differs.

Summary Table: SI Base Units

Quantity	Unit	Abbreviation
Mass	Kilogram	kg
Length	Meter	m
Time	Second	s
Temperature	Kelvin	K
Amount of substance	Mole	mol
Electric current	Ampere	A
Luminous intensity	Candela	cd

Key Concepts for Study

• Distinguish between homogeneous and heterogeneous mixtures.

• Identify compounds vs. elements.

• Differentiate physical and chemical properties.

• Understand the difference between accuracy and precision.

• Know which numbers to report after calculations (significant figures).

• Be able to convert between different units using dimensional analysis.

• Recall SI prefixes and the density equation.

Additional info: For further practice, refer to the end-of-chapter problems listed in the notes. Mastery of these foundational concepts is essential for success in all areas of general chemistry.