UC Davis CHE 1: Preparation for Chemistry

Vocabulary practice flashcards covering core foundational topics for UC Davis CHE 1 (Preparation for Chemistry), including classification of matter, atomic structure, periodic trends, nomenclature, mole stoichiometry, solution concentrations, and chemical reaction types.

Pure Substance

A form of matter that contains only one chemical component or substance with constant composition throughout, categorized as either an element or a compound (e.g., pure gold, pure water, pure oxygen, pure sodium chloride).

Mixture

A material composed of two or more different elements or compounds physically intermingled without fixed proportions (e.g., coffee latte, tea, milk, alloys).

Homogeneous Mixture

A mixture that possesses a uniform composition and appearance that is identical at every point throughout the sample (e.g., salt water, tap water, clean air, brass).

Heterogeneous Mixture

A mixture that is not uniformly distributed in space, having a composition that varies from one region to another (e.g., potting soil, birthday cake, lake water with suspended solids).

Element

A pure substance consisting entirely of atoms having the same atomic number that cannot be decomposed into simpler substances by chemical means.

Compound

A pure substance composed of two or more different types of atoms chemically bonded together in simple, fixed, whole-number ratios.

Extensive Property

A physical property that depends directly on the size, scale, or quantity of matter in a sample (e.g., mass, volume, length).

Intensive Property

A physical property that is independent of the size, scale, or amount of the sample (e.g., temperature, density, color).

Physical Change

A change in the state or appearance of matter that occurs without any alteration to its underlying chemical composition (e.g., melting metal, evaporation of liquid water, sublimation of dry ice).

Chemical Change

A process in which one or more substances are transformed into chemically distinct new substances through the breaking and forming of chemical bonds (e.g., burning of natural gas, rusting of iron).

Law of Definite Proportions

The observation that elements combine to form a specific chemical compound in fixed, constant mass ratios regardless of the source or sample size.

Dalton's Atomic Theory

The 1808 postulate stating that all matter is composed of indivisible atoms; all atoms of an element are identical in mass and properties; atoms combine in fixed whole-number ratios to form compounds; and atoms are rearranged, not created or destroyed, in chemical reactions.

Nuclear Model of the Atom

Rutherford's atomic model demonstrating that an atom is mostly empty space with a tiny, dense, positively charged nucleus at the center and electrons orbiting outside the nucleus.

Cathode Ray

A stream of negatively charged particles (electrons) produced in an evacuated glass tube that travels in straight lines and bends toward a positively charged plate in an electric field.

Millikan's Oil-Drop Experiment

A 1909 experiment that determined the fundamental charge of an electron ($-1.6022 \times 10^{-19}\,\text{C}$) and calculated its mass ($9.1094 \times 10^{-28}\,\text{g}$) by balancing downward gravitational force ($F = mg$) with upward electric force ($F = qE$).

Atomic Number ($Z$)

The number of protons in an atom's nucleus, which uniquely defines the identity and periodic table position of an element.

Mass Number ($A$)

The total integer sum of protons and neutrons in the nucleus of a specific atom.

Atomic Notation

The standard representation of an isotope showing the mass number ($A$) as a superscript, atomic number ($Z$) as a subscript, and element symbol ($\text{X}$) as $^A_Z\text{X}$.

Isotopes

Atoms of the same element containing the identical number of protons but differing numbers of neutrons, resulting in nearly identical chemical properties and slightly different physical properties.

Atomic Mass Unit ($\text{amu}$)

A relative mass unit defined by assigning an atomic mass of exactly $12\,\text{amu}$ to an atom of carbon-12 ($^{12}\text{C}$).

Relative Atomic Mass

The weighted average of the atomic masses of an element's naturally occurring isotopes, calculated based on their fractional abundances.

Alkali Metals

The soft, highly reactive Group IA (1) elements ($\text{Li}$, $\text{Na}$, $\text{K}$, $\text{Rb}$, $\text{Cs}$, $\text{Fr}$) that lose one electron to form $+1$ cations and react vigorously with water to produce basic solutions.

Alkaline Earth Metals

The reactive Group IIA (2) metallic elements ($\text{Be}$, $\text{Mg}$, $\text{Ca}$, $\text{Sr}$, $\text{Ba}$, $\text{Ra}$) that lose two electrons to form $+2$ cations.

Halogens

The highly reactive Group VIIA (17) nonmetal elements ($\text{F}_2$, $\text{Cl}_2$, $\text{Br}_2$, $\text{I}_2$) that exist as diatomic molecules and form $-1$ anions.

Noble Gases

The Group VIIIA (18) elements ($\text{He}$, $\text{Ne}$, $\text{Ar}$, $\text{Kr}$, $\text{Xe}$, $\text{Rn}$) that exist as unreactive, stable monatomic gases with closed electron configurations.

Transition Metals

The metallic elements located in columns 3–12 (Group B) of the periodic table, known for forming cations with multiple oxidation states and yielding colored compounds.

Metalloids

Elements positioned along the metal/nonmetal dividing line ($\text{B}$, $\text{Si}$, $\text{Ge}$, $\text{As}$, $\text{Sb}$, $\text{Te}$) having intermediate electrical conductivity suitable for semiconductors.

Ionic Compound

A compound composed of oppositely charged cations and anions arranged in a rigid crystal lattice with an overall net charge of zero, displaying high melting points and electrical conductivity when molten or aqueous.

Molecular Compound

A compound composed of discrete units of nonmetal atoms held together by covalent bonds, typically exhibiting lower melting and boiling points than ionic compounds.

Strong Electrolyte

A solute that completely dissociates into free ions when dissolved in water, producing an aqueous solution that conducts electricity strongly (e.g., $\text{NaCl}$, $\text{KCl}$).

Weak Electrolyte

A solute that partially dissociates into ions in aqueous solution while the majority remains intact molecules, conducting electricity poorly (e.g., acetic acid, $\text{CH}_3\text{CO}_2\text{H}$).

Nonelectrolyte

A substance that dissolves in water entirely as intact neutral molecules without forming ions, resulting in a solution that does not conduct electricity (e.g., ethanol, sucrose).

Oxoanion

A polyatomic anion containing a central element covalently bonded to one or more oxygen atoms, with names systematically designated using suffixes -ate and -ite and prefixes per- and hypo-.

Carboxylic Acid

An organic acid containing the functional group $\text{-COOH}$ or $\text{-CO}_2\text{H}$ that donates an ionizable acidic hydrogen atom in water.

Hydronium Ion

The hydrated proton species ($\text{H}_3\text{O}^+$) formed when a free hydrogen ion ($\text{H}^+$) associates with a water molecule in aqueous solution.

Mole ($n$)

The SI unit for amount of substance containing the exact number of elementary entities equal to the number of atoms present in exactly $12\,\text{g}$ of pure carbon-12.

Avogadro's Number ($N_A$)

The number of elementary units (atoms, molecules, or formula units) per mole of substance, equal to $6.022 \times 10^{23}\,\text{mol}^{-1}$.

Molar Mass

The mass of one mole of a chemical substance in grams per mole ($\text{g\,mol}^{-1}$), numerically equivalent to its atomic, molecular, or formula mass in $\text{amu}$.

Empirical Formula

The chemical formula showing the simplest whole-number ratio of atoms of each element present in a compound.

Molecular Formula

The chemical formula specifying the actual number of each atom type present in a single discrete molecule of a compound.

Percent Composition by Mass

The percentage contribution of each element to the total mass of a chemical compound, calculated as $\frac{\text{mass of element}}{\text{mass of sample}} \times 100\%$.

Molarity ($M$)

A standard solution concentration unit defined as the number of moles of dissolved solute per liter of total solution volume ($\text{mol\,L}^{-1}$).

Dilution

The procedure of lowering a solution's concentration by adding pure solvent, conserving the moles of solute according to $M_1 V_1 = M_2 V_2$.

Law of Conservation of Mass

The fundamental principle stating that matter is neither created nor destroyed during a chemical reaction, requiring total reactant mass to equal total product mass.

Combination Reaction

A reaction class in which two or more reactant substances unite to form a single chemical compound ($A + B \rightarrow AB$).

Decomposition Reaction

A reaction class in which a single compound reactant breaks down into two or more elements or simpler compounds ($CD \rightarrow C + D$).

Single-Displacement Reaction

A reaction class wherein an uncombined free element displaces another element from a compound to yield a different compound and a new free element ($A + CD \rightarrow C + AD$).

Double-Displacement Reaction

A reaction class involving the exchange of positive and negative ions between two reacting ionic compounds in aqueous solution ($CD + EF \rightarrow CF + ED$).

Activity Series

An empirical hierarchy ordering metals by decreasing chemical reactivity to predict whether a metal can displace another metal or hydrogen from solution.

Spectator Ion

An ion that exists in identical form on both the reactant and product sides of an aqueous reaction without undergoing any chemical transformation.

Net Ionic Equation

A chemical equation representing an aqueous reaction that includes solely the participating ions and molecules while omitting spectator ions.

Limiting Reactant

The reactant that is completely consumed first in a reaction, thereby capping the theoretical amount of product that can be generated.

Theoretical Yield

The maximum calculated quantity of product that could be produced in a reaction based on complete consumption of the limiting reactant.

Percent Yield

The ratio comparing actual product obtained in a reaction to the stoichiometric theoretical yield, calculated as $\frac{\text{actual yield}}{\text{theoretical yield}} \times 100\%$.