CHE 101-01 Final Exam Study Guide: Key Concepts in GOB Chemistry

Final Exam Study Guide Overview

This study guide outlines the essential topics and skills required for the CHE 101-01 Final Exam, covering foundational concepts in General, Organic, and Biological (GOB) Chemistry. The guide is structured to help students review major themes, definitions, and problem-solving strategies relevant to the course.

How Ionic Compounds Form

Formation and Examples

Ionic compounds are formed through the transfer of electrons from one atom to another, resulting in the creation of positively and negatively charged ions that attract each other.

• Ions: Atoms or molecules that have gained or lost electrons, acquiring a charge.

• Cation: A positively charged ion (e.g., Na+).

• Anion: A negatively charged ion (e.g., Cl-).

• Example: Sodium chloride (NaCl) forms when sodium donates an electron to chlorine.

Equation:

$\text{Na} \rightarrow \text{Na}^+ + e^-$

$\text{Cl} + e^- \rightarrow \text{Cl}^-$

$\text{Na}^+ + \text{Cl}^- \rightarrow \text{NaCl}$

How Covalent Compounds Form

Formation and Examples

Covalent compounds are formed when two atoms share one or more pairs of electrons, resulting in a stable molecule.

• Covalent Bond: A chemical bond formed by the sharing of electron pairs between atoms.

• Example: Water (H2O) forms when hydrogen and oxygen share electrons.

Equation:

$\text{H}_2 + \text{O} \rightarrow \text{H}_2\text{O}$

Positive and Negative Ions

Formation and Identification

Positive ions (cations) form when atoms lose electrons, while negative ions (anions) form when atoms gain electrons.

• Example: Magnesium loses two electrons to form Mg2+; oxygen gains two electrons to form O2-.

Electron Transfer in Ionic Compounds

Mechanism and Examples

Electron transfer is the process by which atoms achieve stable electron configurations, typically resulting in the formation of ionic compounds.

• Example: Formation of calcium chloride (CaCl2).

Equation:

$\text{Ca} \rightarrow \text{Ca}^{2+} + 2e^-$

$2\text{Cl} + 2e^- \rightarrow 2\text{Cl}^-$

$\text{Ca}^{2+} + 2\text{Cl}^- \rightarrow \text{CaCl}_2$

Oxidation and Reduction

Definitions and Applications

Oxidation is the loss of electrons, while reduction is the gain of electrons. These processes are fundamental to many chemical reactions.

• Oxidation: Loss of electrons (increase in oxidation state).

• Reduction: Gain of electrons (decrease in oxidation state).

• Example: In the reaction between zinc and copper(II) sulfate, zinc is oxidized and copper is reduced.

Equation:

$\text{Zn} + \text{Cu}^{2+} \rightarrow \text{Zn}^{2+} + \text{Cu}$

Balancing Chemical Equations

Steps and Importance

Balancing chemical equations ensures that the same number of atoms of each element are present on both sides of the reaction.

• Identify reactants and products.

• Count the number of atoms of each element.

• Add coefficients to balance the atoms.

• Example: $\text{2H}_2 + \text{O}_2 \rightarrow \text{2H}_2\text{O}$

Identifying Limiting Reactant and Theoretical Yield

Concepts and Calculations

The limiting reactant is the substance that is completely consumed first, limiting the amount of product formed. The theoretical yield is the maximum amount of product that can be formed from the limiting reactant.

• Calculate moles of each reactant.

• Determine which reactant produces the least amount of product.

• Example: In the reaction $\text{N}_2 + 3\text{H}_2 \rightarrow 2\text{NH}_3$, if you have 1 mol N2 and 3 mol H2, both are limiting together.

Types of Chemical Reactions

Classification and Examples

Chemical reactions can be classified into several types based on the changes that occur.

• Synthesis: Two or more substances combine to form one product.

• Decomposition: One substance breaks down into two or more products.

• Single Replacement: One element replaces another in a compound.

• Double Replacement: Exchange of ions between two compounds.

• Combustion: Reaction with oxygen producing heat and light.

Acids and Bases

Definitions and Properties

Acids are substances that donate protons (H+), while bases accept protons or donate hydroxide ions (OH-).

• Acid: pH less than 7, sour taste, turns litmus red.

• Base: pH greater than 7, bitter taste, turns litmus blue.

• Example: Hydrochloric acid (HCl) and sodium hydroxide (NaOH).

pH and pKa Calculations

Formulas and Applications

pH measures the acidity of a solution, while pKa is the negative logarithm of the acid dissociation constant (Ka).

• pH Formula: $\text{pH} = -\log[\text{H}^+]$

• pKa Formula: $\text{pKa} = -\log K_a$

• Use these formulas to calculate acidity and strength of acids.

Electron Configuration and Atomic Structure

Key Concepts

Atoms are composed of protons, neutrons, and electrons. Electron configuration describes the arrangement of electrons in an atom.

• Atomic Number: Number of protons in the nucleus.

• Mass Number: Sum of protons and neutrons.

• Electron Configuration: Distribution of electrons among energy levels and orbitals.

• Example: Carbon: Atomic number 6, electron configuration 1s2 2s2 2p2.

Standard Temperature and Pressure (STP) and Charles's Law

Definitions and Calculations

STP refers to a standard set of conditions for temperature and pressure used in gas calculations. Charles's Law describes the relationship between volume and temperature of a gas at constant pressure.

• STP: 0°C (273.15 K) and 1 atm pressure.

• Charles's Law: $\frac{V_1}{T_1} = \frac{V_2}{T_2}$

• Use Charles's Law to solve for unknown volume or temperature.

Molecular Compounds

Definition and Naming

Molecular compounds consist of nonmetal atoms bonded covalently. Naming follows specific rules based on the number and type of atoms present.

• Example: CO2 is named carbon dioxide; H2O is named water.

• Prefixes (mono-, di-, tri-, etc.) indicate the number of atoms.

Summary Table: Atomic Structure Terms

Term	Definition	Example
Atomic Number	Number of protons in the nucleus	Carbon: 6
Mass Number	Sum of protons and neutrons	Carbon-12: 6 protons + 6 neutrons = 12
Electron Configuration	Arrangement of electrons in shells and subshells	1s2 2s2 2p2

Additional info: Some details, such as specific examples and equations, have been expanded for clarity and completeness.