General Chemistry Exam 1 Study Guide: Matter, Measurement, Atomic Structure, and Chemical Nomenclature

Introduction: Matter, Energy, and Measurement

Definitions and Properties of Matter

• Atom: The smallest unit of an element that retains the chemical properties of that element.

• Molecule: A group of two or more atoms bonded together.

• Properties of Matter: Characteristics used to describe matter, such as mass, volume, density, and composition.

• Heterogeneous vs. Homogeneous:

  • Heterogeneous mixture: Composition is not uniform throughout (e.g., salad, granite).

  • Homogeneous mixture: Composition is uniform throughout (e.g., salt water, air).

• Chemical vs. Physical Changes:

  • Physical change: Alters the form or appearance but not the composition (e.g., melting ice).

  • Chemical change: Produces new substances (e.g., burning wood).

• Metals, Nonmetals, Metalloids:

  • Metals: Conduct electricity, malleable, shiny.

  • Nonmetals: Poor conductors, brittle, dull.

  • Metalloids: Properties intermediate between metals and nonmetals.

Phases and Classifications of Matter

• Phases of Matter: Solid, liquid, gas.

  • Solid: Definite shape and volume.

  • Liquid: Definite volume, indefinite shape.

  • Gas: Indefinite shape and volume.

• Classifications of Matter:

  • Pure substances: Elements and compounds.

  • Mixtures: Homogeneous and heterogeneous.

Physical and Chemical Properties

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

• Chemical properties: Describe how a substance reacts (e.g., flammability, reactivity).

SI Units and Metric Prefixes

• SI Base Units:

  • Length: meter (m)

  • Mass: kilogram (kg)

  • Time: second (s)

  • Temperature: kelvin (K)

  • Amount of substance: mole (mol)

  • Electric current: ampere (A)

  • Luminous intensity: candela (cd)

• Derived Units:

  • Volume: cubic meter (m3), liter (L)

  • Density: kilogram per cubic meter (kg/m3), gram per milliliter (g/mL)

• Metric Prefixes:

Prefix	Symbol	Value
tera	T	1012
giga	G	109
mega	M	106
kilo	k	103
deci	d	10-1
centi	c	10-2
milli	m	10-3
micro	μ	10-6
nano	n	10-9
pico	p	10-12
femto	f	10-15

Unit Conversions and Dimensional Analysis

• Dimensional Analysis: Method to convert between units using conversion factors.

• Example: To convert 5.0 km to meters:

  • Use conversion factor: $1\ \text{km} = 1000\ \text{m}$

  • $5.0\ \text{km} \times \frac{1000\ \text{m}}{1\ \text{km}} = 5000\ \text{m}$

Temperature Conversions

• Equations:

  • Celsius to Fahrenheit: $F = \frac{9}{5}C + 32$

  • Fahrenheit to Celsius: $C = \frac{5}{9}(F - 32)$

  • Celsius to Kelvin: $K = C + 273.15$

Density Calculations

• Density: Mass per unit volume.

• Equation: $\text{Density} = \frac{\text{Mass}}{\text{Volume}}$

• Units: Commonly g/mL or g/cm3.

• Example: If a block has mass 20 g and volume 5 mL, density is $\frac{20\ \text{g}}{5\ \text{mL}} = 4\ \text{g/mL}$

Scientific Notation and Significant Figures

• Scientific Notation: Expresses numbers as a product of a coefficient and a power of ten (e.g., $3.2 \times 10^4$).

• Significant Figures: Digits in a measurement that are known with certainty plus one estimated digit.

• Reporting Values: Use correct number of significant figures based on measurement precision.

• Example: $0.00450$ has three significant figures.

Atoms, Molecules, and Ions

Periodic Table and Element Classification

• First 36 Elements: Know symbols and names (e.g., H for hydrogen, He for helium, etc.).

• Column Names:

  • Group 1: Alkali metals

  • Group 2: Alkaline earth metals

  • Group 17: Halogens

  • Group 18: Noble gases

• Metals, Nonmetals, Metalloids: Location on periodic table:

  • Metals: Left and center

  • Nonmetals: Right

  • Metalloids: Border between metals and nonmetals

Structure of the Atom

• Protons: Positively charged particles in nucleus.

• Neutrons: Neutral particles in nucleus.

• Electrons: Negatively charged particles orbiting nucleus.

• Atomic Symbol: Represents element, mass number, and atomic number (e.g., $^{24}_{12}\text{Mg}$).

• Mass Number ($A$): $A = \text{number of protons} + \text{number of neutrons}$

• Atomic Number ($Z$): $Z = \text{number of protons}$

Isotopes and Atomic Mass

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

• Average Atomic Mass: Weighted average of isotopes based on abundance.

• Equation: $\text{Average atomic mass} = \sum (\text{isotope mass} \times \text{fractional abundance})$

• Example: If $^{12}\text{C}$ is 98.9% and $^{13}\text{C}$ is 1.1%, average mass = $(12 \times 0.989) + (13 \times 0.011)$

Basic Concepts of Chemical Bonding

Ionic vs. Molecular Compounds

• Ionic Compounds: Formed from transfer of electrons between metals (cations) and nonmetals (anions).

• Molecular Compounds: Formed from sharing electrons between nonmetals (covalent bonds).

• Properties:

  • Ionic: High melting points, conduct electricity when dissolved.

  • Molecular: Lower melting points, do not conduct electricity.

Polyatomic Ions

• Polyatomic Ion: A charged group of covalently bonded atoms (e.g., NO3-, SO42-).

• Know: Names, formulas, and charges of common polyatomic ions.

Periodic Trends and Ion Formation

• Metals: Tend to form cations (positive ions).

• Nonmetals: Tend to form anions (negative ions).

• Charge Prediction: Based on group number (e.g., Group 1 forms +1, Group 17 forms -1).

Chemical Nomenclature

Determining Chemical Formulas and Names

• Ionic Compounds: Name cation first, then anion. For transition metals, indicate charge with Roman numerals.

• Molecular Compounds: Use prefixes (mono-, di-, tri-, tetra-, etc.) to indicate number of atoms.

• Binary Acids: Use "hydro-" prefix and "-ic" ending (e.g., hydrochloric acid).

• Oxyacids: Based on polyatomic ion; "-ate" becomes "-ic acid", "-ite" becomes "-ous acid" (e.g., sulfuric acid from sulfate).

• Example: $\text{CO}_2$ is carbon dioxide; $\text{FeCl}_3$ is iron(III) chloride.

Charge Determination for Transition Metals

• Transition Metals: May have multiple possible charges; use Roman numerals in name (e.g., iron(II) vs. iron(III)).

• Determine charge: Based on anion charge and formula.

• Example: In $\text{FeCl}_3$, Cl is -1, so Fe must be +3.

Prefixes for Molecular Compounds

• mono- (1), di- (2), tri- (3), tetra- (4), penta- (5), hexa- (6), hepta- (7), octa- (8), nona- (9), deca- (10)

• Example: $\text{N}_2\text{O}_4$ is dinitrogen tetroxide.

Additional info: Academic context and examples were added to clarify definitions, formulas, and procedures for self-contained study notes.