Ch. 1 Lecture Notes: Measurement and the Properties of Matter

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Ch.1 Lecture Notes: Measurement and the Properties of Matter

1.1 Chemistry: The Central Science

Chemistry is often called the "central science" because it connects and overlaps with many other scientific disciplines, including biology, physics, geology, medicine, and environmental science.

Chemistry: The study of the nature, properties, and transformations of matter.
Matter: Anything that has mass and occupies space.
Property: A characteristic used to describe or identify something.
Transformation: A change in the properties of matter over time, which can be physical or chemical.

1.2 Properties and Changes in Matter

Substances possess both physical and chemical properties, which determine how they behave and interact.

Physical Properties: Can be observed without changing the substance's chemical identity (e.g., density, color, melting point).
Chemical Properties: Observed when a substance undergoes a chemical change, resulting in a new substance (e.g., flammability, reactivity).
Physical Change: Does not alter the chemical makeup (e.g., changes in state, particle size, or formation/separation of mixtures).
Chemical Change: Alters the chemical makeup, forming new substances (e.g., burning, rusting, decomposition).

Example: Ice melting to water is a physical change; burning coal is a chemical change.

1.3 States of Matter

Matter exists in three common states: solid, liquid, and gas. The state depends on temperature and pressure.

Solid (s): Definite shape and volume; rigid and dense (e.g., ice cube).
Liquid (l): Definite volume but indefinite shape; takes the shape of its container (e.g., ethanol).
Gas (g): No definite shape or volume; expands to fill the container (e.g., oxygen).

Example: Water can exist as ice (solid), liquid water, or steam (gas) depending on temperature.

1.4 Classification of Matter

Matter can be classified as pure substances or mixtures.

Pure Substances: Uniform composition; contains only one type of substance (element or compound).
Mixtures: Blend of two or more pure substances; each retains its identity and properties.

Pure Substances

Element: Contains only one type of atom; cannot be broken down chemically (e.g., C, H2, O2).
Compound: Contains atoms of two or more elements chemically combined in fixed ratios; can be broken down into elements (e.g., H2O, NaHCO3).

Mixtures

Homogeneous Mixture: Uniform composition throughout (e.g., saltwater).
Heterogeneous Mixture: Non-uniform composition (e.g., salad, concrete).

1.5 Chemical Elements and Symbols

Elements are represented by symbols, usually one or two letters (first letter capitalized, second lowercase). Some symbols are derived from Latin names.

Examples: Carbon (C), Calcium (Ca), Cobalt (Co), Sodium (Na), Silver (Ag)

The periodic table organizes all known elements based on their properties. Elements are divided into metals, nonmetals, and metalloids (semi-metals).

Metals: Left side of the periodic table; shiny, good conductors, malleable, ductile.
Nonmetals: Right side; poor conductors, can be gases, brittle solids, or liquids.
Metalloids: Along the zigzag line; properties intermediate between metals and nonmetals.

1.6 Chemical Formulas

Chemical formulas use elemental symbols and subscripts to indicate the number of atoms of each element in a compound.

Example: H2O (2 hydrogen, 1 oxygen), C6H12O6 (glucose)

1.7 Physical Quantities, Units, and Scientific Notation

Physical quantities are measured using numbers and units. The SI (International System) and metric systems are standard in science.

Quantity	SI Unit (Symbol)	Metric Unit (Symbol)	Equivalents
Mass	kilogram (kg)	gram (g)	1 kg = 1000 g = 2.205 lb
Length	meter (m)	meter (m)	1 m = 3.280 ft
Volume	cubic meter (m3)	liter (L)	1 m3 = 1000 L = 264.2 gal
Temperature	kelvin (K)	Celsius (°C)	--
Time	second (s)	second (s)	--

Prefixes are used to express very large or small quantities (e.g., kilo-, centi-, milli-).

Scientific Notation is used to express large or small numbers as a value between 1 and 10 multiplied by a power of 10.

Example: for 4579

1.8 Significant Figures

Significant figures reflect the precision of a measurement. All known digits plus one estimated digit are significant.

Zeros between nonzero digits are significant (e.g., 305 has 3 significant figures).
Leading zeros are not significant (e.g., 0.012 has 2 significant figures).
Trailing zeros after a decimal point are significant (e.g., 2.300 has 4 significant figures).
Exact numbers (e.g., 12 eggs) have infinite significant figures.

Rules for Calculations:

Multiplication/Division: Result has as many significant figures as the value with the fewest significant figures.
Addition/Subtraction: Result has as many decimal places as the value with the fewest decimal places.

1.9 Unit Conversions and the Factor-Label Method

Unit conversions use conversion factors to change from one unit to another. The factor-label (dimensional analysis) method ensures units cancel appropriately.

Example: To convert 3.0 yards to centimeters, use the relationships: 1 yd = 3 ft, 1 ft = 12 in, 1 in = 2.54 cm.

General Steps:

Identify given information and units.
Identify required information and units.
Find relationships (conversion factors).
Solve and check your answer for reasonableness.

1.10 Temperature Scales and Conversions

Temperature can be measured in Celsius (°C), Fahrenheit (°F), or Kelvin (K).

Kelvin (K):
Celsius to Fahrenheit:
Fahrenheit to Celsius:

1.11 Density, Specific Heat, and Specific Gravity

Density, specific heat, and specific gravity are important physical properties.

Density (d): , where is mass and is volume. Units: g/cm3 (solids), g/mL (liquids).
Specific Heat (c): The amount of heat needed to raise the temperature of 1 g of a substance by 1°C. Units: cal/g·°C or J/g·°C.
Heat Equation:
Specific Gravity: Ratio of the density of a substance to the density of water at the same temperature.

Summary Table: Classification of Matter

Type	Description	Examples
Element	Cannot be broken down chemically	O2, Na, Cu
Compound	Two or more elements chemically combined	H2O, NaCl
Homogeneous Mixture	Uniform composition	Saltwater, air
Heterogeneous Mixture	Non-uniform composition	Salad, concrete

Additional info: These notes cover foundational concepts in general chemistry, including the nature and classification of matter, measurement, units, significant figures, and basic calculations essential for laboratory and theoretical work.