Exam 1 Review

Overview

This study guide covers foundational topics in General, Organic, and Biological (GOB) Chemistry, including measurements, atomic theory, chemical compounds, and chemical reactions. These notes are structured to help students prepare for Exam 1 by summarizing key concepts and providing academic context.

Chapter 2: Measurements and Problem Solving

Types of Measurements

• Qualitative Measurements: Descriptions without numerical values (e.g., color, texture).

• Quantitative Measurements: Measurements with numerical values (e.g., mass, volume).

Units and SI System

• SI Units: Standard units used in science (meter, kilogram, second, liter).

• Volume: Measured in liters (L) or milliliters (mL).

Uncertainty, Accuracy, and Precision

• Uncertainty: The degree of doubt in a measurement.

• Accuracy: How close a measurement is to the true value.

• Precision: How close repeated measurements are to each other.

Scientific Notation and Significant Figures

• Scientific Notation: Expresses numbers as a product of a coefficient and a power of ten (e.g., ).

• Significant Figures: Digits that carry meaning in a measurement. Rules determine which digits are significant.

Metric System and Multipliers

• Metric Prefixes: Used to express multiples of units (e.g., kilo-, centi-, milli-).

Problem Solving: Conversion and Dimensional Analysis

• Conversion Factors: Ratios used to convert between units.

• Dimensional Analysis: A method to solve problems using conversion factors to cancel units.

Physical and Chemical Properties

• Physical Property: Can be observed without changing the substance (e.g., melting point).

• Chemical Property: Describes how a substance reacts (e.g., flammability).

Chapter 4: Atoms & Elements

Atomic Theory

• Atoms: The smallest unit of an element, composed of protons, neutrons, and electrons.

• Subatomic Particles:

  • Protons: Positively charged, found in the nucleus.

  • Neutrons: Neutral, found in the nucleus.

  • Electrons: Negatively charged, found outside the nucleus.

Atomic Number and Mass Number

• Atomic Number (Z): Number of protons in the nucleus.

• Mass Number (A): Sum of protons and neutrons ().

Isotopes and Element Symbols

• Isotopes: Atoms of the same element with different numbers of neutrons.

• Element Symbol: One- or two-letter abbreviation for an element (e.g., H for hydrogen).

Periodic Table and Classification

• Groups/Families: Vertical columns (e.g., Alkali Metals - Group 1A, Noble Gases - Group 8A).

• Periods: Horizontal rows.

• Main Group Elements (A): Groups 1A-8A.

• Transition Metals (B): Groups in the center of the table.

• Metals, Nonmetals, Metalloids: Classification based on properties.

Periodic Law and Properties

• Periodic Law: Properties of elements repeat periodically when arranged by atomic number.

• Chemical Properties: Reactivity, ion formation, etc.

Chapter 6: Ionic & Molecular Compounds and Chemical Equations

Ionic Compounds

• Ions: Charged particles formed by loss or gain of electrons.

  • Cations: Positively charged (Type 1: fixed charge, Type 2: variable charge).

  • Anions: Negatively charged.

• Formulas: Represent the ratio of ions in a compound.

• Naming Ionic Compounds:

  • Type 1: Cation + Anion (ending in -ide).

  • Type 2: Cation (with charge in Roman numerals) + Anion (ending in -ide).

Molecular Compounds

• Covalent Compounds: Formed by sharing electrons between nonmetals.

• Naming: Prefixes indicate number of atoms (e.g., CO2 is carbon dioxide).

Acids and Polyatomic Ions

• Acids:

  • Binary acids: Hydrogen + nonmetal (e.g., HCl).

  • Oxyacids: Hydrogen + polyatomic ion (e.g., H2SO4).

  • Naming rules:

    • -ic acid for ions ending in -ate.

    • -ous acid for ions ending in -ite.

    • Prefixes: per- (more oxygen), hypo- (less oxygen).

• Polyatomic Ions: Ions composed of multiple atoms (e.g., NO3-, SO42-).

Avogadro's Number and Moles

• Avogadro's Number: units/mol.

• Mole: The amount of substance containing Avogadro's number of particles.

Molar Mass and Formula Weight

• Molar Mass: Mass of one mole of a substance (g/mol).

• Formula Weight: Sum of atomic weights in a chemical formula.

Percent Composition

• Percent Composition: Percentage by mass of each element in a compound.

Chapter 6: Lewis Structures

Lewis Structures and Covalent Bonding

• Lewis Structure: Diagram showing valence electrons and bonds in a molecule.

• Octet Rule: Atoms tend to have eight electrons in their valence shell.

• Bond Types:

  • Single Bond: One shared pair of electrons.

  • Double Bond: Two shared pairs.

  • Triple Bond: Three shared pairs.

• Electronegativity: Tendency of an atom to attract electrons.

• Polarity: Distribution of charge in a molecule.

• Molecular Shape: Determined by electron pair geometry (VSEPR theory).

Chapter 7: Chemical Reactions and Quantities

Chemical Reactions and Equations

• Chemical Change: Transformation resulting in new substances.

• Chemical Equation: Representation of a chemical reaction using formulas and symbols.

• Law of Conservation of Matter: Matter is neither created nor destroyed in a chemical reaction.

• Balancing Equations: Ensures equal numbers of atoms on both sides.

Types of Chemical Reactions

• Combination (Synthesis):

• Decomposition:

• Combustion:

• Redox (Oxidation/Reduction): Electron transfer reactions. LEO: Lose Electrons = Oxidation GER: Gain Electrons = Reduction

• Single Displacement:

• Double Displacement:

Stoichiometry and Reaction Quantities

• Stoichiometry: Calculation of reactant and product quantities in chemical reactions.

• Mole Ratios: Derived from balanced equations, used for conversions.

• Stoichiometric Conversions:

  • Mass → Moles → Moles → Mass

  • Use molar mass and mole ratios for calculations.

• Limiting Reagent: The reactant that determines the maximum amount of product.

• Theoretical Yield: Maximum product calculated from limiting reagent.

Appendix: Classification Table of Elements

Appendix: Common Polyatomic Ions

Example Calculations

Mass to Moles Conversion

• Use molar mass:

Stoichiometry Example

• Given a balanced equation, convert grams of reactant to grams of product using mole ratios and molar masses.

Lewis Structure Example

• For H2O: Oxygen shares electrons with two hydrogens, forming two single bonds and completing the octet for oxygen.

Additional info: Academic context and examples have been added to expand upon the original bullet points and ensure completeness for exam preparation.