GOB Chemistry Exam 2 Study Guide: Chapters 4, 5, 6, 7 (Atoms, Elements, Nuclear Chemistry, Ionic & Molecular Compounds, Chemical Reactions & Quantities)

Exam Preparation and Expectations

Overview of Exam Logistics

This section outlines the procedures and expectations for the upcoming GOB Chemistry exam, covering chapters on atoms, elements, nuclear chemistry, ionic and molecular compounds, and chemical reactions and quantities.

• Exam Location: Regular lecture room.

• Time Management: A seating chart and an analog clock will be provided.

• Allowed Materials: Non-graphing calculator (with approval if not standard), periodic table, and a formula sheet.

Study Materials and Strategies

• Study Guides: Provided for each chapter; lecture outlines and study guides are available on the course platform.

• Practice Problems: Located at the end of each study guide and in the textbook; solutions are available for self-assessment.

• Exam Format: Multiple choice questions, definition-based questions, and short calculations.

• Preparation Tips: Focus on understanding concepts, practicing calculations, and reviewing definitions and applications.

Reference Tables and Constants

Miscellaneous Constants

These constants are essential for calculations in chemistry, especially in atomic and molecular contexts.

Constant	Value
Avogadro's Number	6.022 × 1023 items/mole
Mass of Electron	1.6605 × 10-24 g
Mass of Proton	1.0072 amu
Mass of Neutron	1.0086 amu

Unit Conversions

Common conversions for distance, volume, mass, energy, and temperature are provided for use in calculations.

Quantity	Conversion
Distance	1 yd = 0.9144 m; 1 mi = 1.6093 km; 1 in = 2.54 cm
Volume	1 mL = 1 cm3; 1 L = 1.057 qt; 1 gal = 3.785 L
Mass	1 kg = 2.205 lb; 1 lb = 454 g
Energy	1 cal = 4.184 J; 1 kcal = 1000 cal
Temperature	Absolute zero = 0 K = -273.15 °C = -459.67 °F

Polyatomic Ions

Polyatomic ions are commonly encountered in ionic compounds and chemical reactions.

Ion	Formula
Acetate	CH3COO-
Ammonium	NH4+
Bicarbonate	HCO3-
Carbonate	CO32-
Chlorate	ClO3-
Chlorite	ClO2-
Cyanide	CN-
Dichromate	Cr2O72-
Hydroxide	OH-
Nitrate	NO3-
Nitrite	NO2-
Perchlorate	ClO4-
Phosphate	PO43-
Sulfate	SO42-
Sulfite	SO32-
Thiocyanate	SCN-

The Periodic Table of Elements

Organization and Use

The periodic table is a fundamental tool in chemistry, organizing elements by atomic number and properties. It is used to predict chemical behavior, identify element groups, and determine electron configurations.

• Groups (Columns): Elements with similar chemical properties.

• Periods (Rows): Elements with the same number of electron shells.

• Element Symbols: One- or two-letter abbreviations for each element.

Naming and Structure of Compounds

Prefixes for Number of Atoms

Prefixes are used in naming molecular compounds to indicate the number of atoms of each element present.

Number of Atoms	Prefix
1	mono-
2	di-
3	tri-
4	tetra-
5	penta-
6	hexa-
7	hepta-
8	octa-
9	nona-
10	deca-

VSEPR Geometry and Molecular Shapes

The Valence Shell Electron Pair Repulsion (VSEPR) theory predicts the shapes of molecules based on the number of bonding and lone electron pairs around a central atom.

VSEPR Geometry	Bonding Electron Groups	Lone Pair Electron Groups	Shape Around Central Atom (A)	Approximate Bond Angle (°)
AB2	2	0	Linear	180
AB3	3	0	Trigonal Planar	120
AB2E	2	1	Bent	120
AB4	4	0	Tetrahedral	109
AB3E	3	1	Trigonal Pyramidal	109
AB2E2	2	2	Bent	109

Key Equations and Concepts

Avogadro's Number

Used to convert between moles and number of particles.

• $N = n \times N_A$

• Where N is the number of particles, n is the number of moles, and NA is Avogadro's number.

Unit Conversion Equations

• $\text{Distance:} \quad 1 \text{ yd} = 0.9144 \text{ m}$

• $\text{Volume:} \quad 1 \text{ L} = 1.057 \text{ qt}$

• $\text{Mass:} \quad 1 \text{ kg} = 2.205 \text{ lb}$

• $\text{Energy:} \quad 1 \text{ cal} = 4.184 \text{ J}$

• $\text{Temperature:} \quad K = ^\circ C + 273.15$

Lewis Structures and Molecular Geometry

• Draw Lewis structures to determine the arrangement of atoms and electron pairs.

• Apply VSEPR theory to predict molecular shape and bond angles.

Polyatomic Ion Naming

• Recognize common polyatomic ions and their formulas for naming ionic compounds.

• Example: Sodium sulfate is Na2SO4.

Additional info:

• These notes cover foundational concepts for GOB Chemistry chapters 4-7, including atomic structure, periodic table usage, nuclear chemistry, ionic and molecular compounds, and chemical reactions and quantities.

• Students should be familiar with the periodic table, polyatomic ions, unit conversions, and molecular geometry for success on the exam.