Final Gen Chem 1 Exam Ultimate Study Guide

Matter

Occupies space and has mass; the atom is its fundamental functional unit.

Element

Simplest matter composed of a single kind of atom.

Compound

Substance composed of two or more different elements chemically bonded in fixed ratios.

Mixture

Physical combination of elements or compounds with variable composition.

Homogeneous mixture

Mixture with uniform composition throughout.

Heterogeneous mixture

Mixture with non-uniform composition; includes suspensions and colloids.

Physical change

Change that alters physical state or appearance without altering composition (e.g., phase transitions, dissolving).

Chemical change

Change that transforms substances into chemically distinct species via bond formation or breakage.

Intensive property

Property independent of sample size (e.g., density, temperature, melting point).

Extensive property

Property dependent on sample amount (e.g., mass, volume, internal energy).

Density

Mass divided by volume: $d = \frac{m}{V}$

Law of Conservation of Mass (Lavoisier)

Mass is neither created nor destroyed during a chemical reaction; total mass of reactants equals total mass of products.

Law of Definite Proportions (Proust)

Different samples of a pure chemical compound always contain the same proportions of constituent elements by mass.

Law of Multiple Proportions (Dalton)

When two elements form more than one compound, the masses of one element combining with a fixed mass of the other are in ratios of small whole numbers.

Proton

Positively charged subatomic particle with charge $+1.60218 \times 10^{-19}\,\text{C}$ and mass $1.67262 \times 10^{-27}\,\text{kg}$.

Neutron

Neutral subatomic particle with mass $1.67493 \times 10^{-27}\,\text{kg}$.

Electron

Negatively charged subatomic particle with charge $-1.60218 \times 10^{-19}\,\text{C}$ and mass $9.11 \times 10^{-31}\,\text{kg}$.

Atomic Mass Unit (amu or Da)

One twelfth the mass of a carbon-12 atom: $1\,\text{amu} = 1.66054 \times 10^{-27}\,\text{kg}$.

Millikan Oil Drop Experiment

Experiment by Robert Millikan and Harvey Fletcher that determined the fundamental charge of an electron using charged oil droplets between electric plates.

Rutherford Gold Foil Experiment

Experiment by Rutherford, Geiger, and Marsden bombarding gold foil with alpha particles, revealing a tiny, dense, positively charged nucleus surrounded by empty space.

Isotopes

Atoms of the same element with the same atomic number (Z) but different mass numbers (A).

Average Atomic Mass

Weighted sum of isotopic masses times fractional abundances: $\text{Atomic Mass} = \sum [(\text{Isotopic Mass}) \times (\text{Fractional Abundance})]$

Period

Horizontal rows of the periodic table, where elements are arranged by increasing atomic number.

Group

Vertical columns of the periodic table sharing similar valence shell configurations and chemical properties.

Metals

Elements that are ductile, malleable, conduct electricity and heat, and form cations.

Nonmetals

Elements that are poor conductors, form brittle solids or gases, and form anions.

Metalloids

Semimetals along the staircase border of the periodic table: B, Si, Ge, As, Sb, Te, At.

Alkali Metals

Group 1A elements.

Alkaline Earth Metals

Group 2A elements.

Chalcogens

Group 6A elements.

Halogens

Group 7A elements.

Noble Gases

Group 8A elements.

Roman Numeral Nomenclature

Roman numeral notation indicating the charge of a variable-charge metal cation (e.g., $\text{Fe}^{3+}$ is Iron(III)).

Empirical Formula

Smallest whole-number ratio of atoms in a compound.

Molecular Formula

Whole-number multiple of the empirical formula: $n = \frac{\text{Molar Mass}}{\text{Empirical Formula Mass}}$

Combustion Analysis

Hydrocarbon burning with O_2 to yield CO_2 and H_2O, used to derive carbon and hydrogen masses.

Mole

Amount of substance containing $6.022 \times 10^{23}$ particles (Avogadro's number).

Limiting Reagent

Reactant producing the smallest stoichiometric yield of product; it dictates the theoretical yield.

Percent Yield

Actual yield divided by theoretical yield, times 100%: $\left( \frac{\text{Actual Yield}}{\text{Theoretical Yield}} \right) \times 100\%$

Molarity (M)

Moles of solute per liter of solution: $\frac{\text{moles of solute}}{\text{liters of solution}}$

Dilution Equation

Relationship used to dilute solutions: $M_1V_1 = M_2V_2$

Strong Electrolyte

Substances that dissociate completely into ions in water, such as strong acids, strong bases, and soluble ionic salts.

Weak Electrolyte

Substances that dissociate only partially into ions in water.

Nonelectrolyte

Substances that dissolve in water as neutral molecules and do not conduct electric current.

Precipitation

Reaction in which an insoluble solid forms from aqueous ions, judged by solubility guidelines.

Neutralization

Reaction of an acid and a base to form a salt and water: $\text{Acid} + \text{Base} \rightarrow \text{Salt} + \text{H}_2\text{O}$

Oxidation

Loss of electrons, with an increase in oxidation number; the species acts as a reducing agent.

Reduction

Gain of electrons, with a decrease in oxidation number; the species acts as an oxidizing agent.

Activity Series

Ranking of metals in which higher metals displace lower metals or displace H_2 from acids.

First Law of Thermodynamics

Law stating energy cannot be created or destroyed: $\Delta E_{\text{universe}} = 0$.

Internal Energy

Change in internal energy equal to heat plus work: $\Delta E = q + w$

Pressure-Volume Work

Pressure-volume work: $w = -P\Delta V$, where $1\,\text{L}\cdot\text{atm} = 101.325\,\text{J}$.

Enthalpy

Heat transferred at constant pressure: $\Delta H = q_p$.

Exothermic

Reaction releasing heat to surroundings, with $\Delta H < 0$.

Endothermic

Reaction absorbing heat from surroundings, with $\Delta H > 0$.

Heat Transfer Formula

Heat transfer equation: $q = m c \Delta T$

Constant-Pressure Calorimetry (Coffee Cup)

Calorimetry at fixed atmospheric pressure in an open system: $q_{\text{rxn}} = -(q_{\text{solution}} + q_{\text{cal}})$

Constant-Volume Calorimetry (Bomb)

Calorimetry in a rigid container with fixed volume, so $w = 0$: $q_{\text{rxn}} = -C_{\text{cal}}\Delta T$

Hess's Law

The enthalpy change of an overall reaction equals the sum of the enthalpy changes of its individual steps.

Standard Enthalpy of Reaction

Standard enthalpy of reaction: $\Delta H^\circ_{\text{rxn}} = \sum n\Delta H^\circ_f(\text{products}) - \sum m\Delta H^\circ_f(\text{reactants})$

Standard Enthalpy of Formation of Elements

Pure elements in their standard reference states have $\Delta H^\circ_f = 0\,\text{kJ/mol}$.