Fall 2025 CHM2045 Exam 1 Study Guide

Fall 2025 General Chemistry 1 Study Guide

  • Physical Properties: Describes appearance.

    • Extensive Property: Depends on the amount of substance present (e.g., mass, volume).

    • Intensive Property: Does not depend on the amount (e.g., density, boiling point).

    • Density Formula: d=massvolumed = \frac{\text{mass}}{\text{volume}}

  • Chemical Properties: Displayed only via a chemical change (e.g., flammability).

  • Standardized Measurement System: Universal base units for measurements.

    • SI Base Units:

    • Mass: kilogram (kg)

    • Length: meter (m)

    • Time: second (s)

    • Temperature: Kelvin (K)

    • Amount of Substance: mole (mol)

Common Decimal Prefixes

Prefix

Abbreviation

Meaning

Example

tera-

T

101210^{12}

1 g = 1×10−121 \times 10^{-12} Tg

giga-

G

10910^{9}

1 g = 1×10−91 \times 10^{-9} Gg

mega-

M

10610^{6}

1 g = 1×10−61 \times 10^{-6} Mg

kilo-

k

10310^{3}

1 g = 1×10−31 \times 10^{-3} kg

hecto-

h

10210^{2}

1 g = 1×10−21 \times 10^{-2} hg

deka-

da

10110^{1}

1 g = 1×10−11 \times 10^{-1} dag

base unit

10010^{0}

1 g = 1 g

deci-

d

10−110^{-1}

1 g = 1×10−11 \times 10^{-1} dg

centi-

c

10−210^{-2}

1 g = 1×10−21 \times 10^{-2} cg

milli-

m

10−310^{-3}

1 g = 1×10−31 \times 10^{-3} mg

micro-

µ

10−610^{-6}

1 g = 1×10−61 \times 10^{-6} µg

nano-

n

10−910^{-9}

1 g = 1×10−91 \times 10^{-9} ng

pico-

p

10−1210^{-12}

1 g = 1×10−121 \times 10^{-12} pg

femto-

f

10−1510^{-15}

1 g = 1×10−151 \times 10^{-15} fg

Significant Figures
Fall 2025 General Chemistry 1 Study Guide

  • Physical Properties: Describes appearance.

    • Extensive Property: Depends on the amount of substance present (e.g., mass, volume).

    • Intensive Property: Does not depend on the amount (e.g., density, boiling point).

    • Density Formula: d=massvolumed=volumemass​

  • Chemical Properties: Displayed only via a chemical change (e.g., flammability).

  • Standardized Measurement System: Universal base units for measurements.

    • SI Base Units:

    • Mass: kilogram (kg)

    • Length: meter (m)

    • Time: second (s)

    • Temperature: Kelvin (K)

    • Amount of Substance: mole (mol)

Common Decimal Prefixes

Significant Figures

  • The number of significant figures in a measurement can affect the precision of calculated results; therefore, it is crucial to apply the appropriate rules when performing calculations.

  • Rules for determining significant figures include:

    • Any non-zero digit is significant.

    • Zeros between significant digits are also significant.

    • Leading zeros are not significant, while trailing zeros in a decimal number are.

  • Multiplication/Division: Result must have the same number of significant figures as the value with the least significant figures.

    • Example: For 1.39×2.7=3.81.39 \times 2.7 = 3.8 (not 3.753)

  • Addition/Subtraction: Result must match the decimal places of the least precise measurement.

    • Example: 4.42+4.2=8.64.42 + 4.2 = 8.6 (not 8.62)

  • Purpose: Convert units from one form to another.

  • Guidelines:

    1. Write out all information given.

    2. Connect all information.

    3. Convert to the requested units.

    4. Solve the equation.

Atomic Structure

  • Atom Composition:

    • Central core nucleus with electrons surrounding it.

    • Nucleus Components:

    • Protons (positive charge)

    • Neutrons (no charge)

    • Protons and neutrons have similar mass (≈ 1.67×10−24extg1.67 \times 10^{-24} ext{g} or 1 amu)

    • Electrons:

    • Negative charge with negligible mass (≈ 0.00055extamu0.00055 ext{amu} or 9.109×10−28extg9.109 \times 10^{-28} ext{g}).

Atomic Number and Mass Number

  • Atomic Number: Number of protons in an atom's nucleus.

  • Mass Number: Total of protons and neutrons in the nucleus.

    • Notation: ZAX^{A}_{Z}X where:

    • X = element symbol

    • A = mass number

    • Z = atomic number

Isotopes

  • Definition: Variants of elements with the same protons but different neutrons.

  • Example: 14N^{14}N and 15N^{15}N (same proton number, different mass numbers).

  • Relative Abundance: Percentage of an isotope in nature must equal 100%.

    • Formula: Avg.AtomicMass=(Mass<em>1)(RelativeAbundance</em>1)+(Mass<em>2)(RelativeAbundance</em>2)Avg. Atomic Mass = (Mass<em>1)(Relative Abundance</em>1) + (Mass<em>2)(Relative Abundance</em>2)

Periodic Table Structure

  • Elements: 118 discovered thus far, categorized based on properties.

  • Groups/Families: Elements with similar characteristics, with common trends:

    • Metals: Lose electrons in reactions; good conductors.

    • Nonmetals: Gain/Share electrons; poor conductors.

    • Metalloids: Transitional properties of metals and nonmetals.

Naming Compounds and Ions

  • Ionic Compounds: Formed via electron transfer donate and share outer electrons.

    • Cation: Positive ion; Anion: Negative ion.

  • Valence States: Reflect the number of electrons gained/lost during bond formation.

  • Common Naming Practices:

    • Cation named first, anion second (nonmetal root + -ide).

    • Use Roman numerals for transition metals.

    • For polyatomic ions, know common formulas and names (e.g., sulfate SO42−SO_4^{2-}).

Common Problems for Review

  • Practical Problems:

    • Problem C1: Determine and recognize chemical properties.

    • Problem C4: Identify mass/weight relationships in solutions.

    • End of Packet Problems: A series of application questions for practical understanding.

Review Questions

  • Be familiar with questions that ask about isotopes, atomic structure, and properties of elements. Practices such as dimensional analysis will strengthen your understanding.

This extensive study guide serves as a comprehensive resource for preparing for Exam 1 in CHM2045, summarizing significant concepts, definitions, and examples that will be covered in the exam.