General Chemistry: Measurement, Atomic Structure, Nomenclature, and Stoichiometry

Vocabulary flashcards covering measurement, temperature scales, dimensional analysis, atomic structure, isotopes, periodic table groups, ionic and covalent nomenclature, acids, hydrates, the mole concept, molar mass, and empirical/molecular formulas based on Chem 101 lecture transcripts.

Chemistry

The branch of science that studies matter and energy, as well as the changes that matter undergoes.

Fahrenheit Scale

A temperature scale common in the United States where pure water freezes at $32\,^\circ\text{F}$ and boils at $212\,^\circ\text{F}$.

Celsius Scale

A metric temperature scale where pure water freezes at $0\,^\circ\text{C}$ and boils at $100\,^\circ\text{C}$.

Kelvin Scale

The SI base unit scale for thermodynamic temperature starting at absolute zero ($0\,\text{K}$), where an increment of $1\,\text{K}$ equals $1\,^\circ\text{C}$.

Conversion Factor

A fraction whose numerator and denominator represent equal quantities expressed in different units, evaluated to equal $1$.

Dimensional Analysis

Also known as the factor-label method; a problem-solving process that uses conversion factors to set up calculations so that unwanted units cancel out.

Accuracy

The closeness of the average of a set of measured values to the true or accepted value.

Precision

The closeness of a set of repeated measurements to one another.

Accuracy and Precision Diagram

A dartboard diagram illustrating (a) high precision with low accuracy (grouped off-center), (b) high accuracy and high precision (grouped at the bullseye), and (c) low accuracy and low precision (scattered across the board).

Significant Figures

The digits in a measured quantity that carry meaning regarding the precision of the measuring instrument, including all non-zero digits, captive zeros, and trailing zeros when a decimal point is present.

Exact Numbers

Quantities with no uncertainty, such as defined unit equivalences or counted items, which do not limit the number of significant figures in calculations.

Periodicity

The repeating pattern of physical and chemical trends across rows (periods) of the periodic table.

Groups

The vertical columns on the periodic table containing elements that generally exhibit similar chemical properties.

Metals

Elements located on the left and center of the periodic table that are typically shiny, malleable, electrically conductive, and solid at room temperature.

Nonmetals

Elements located on the upper right side of the periodic table that are non-conductive and brittle when solid.

Metalloids

Elements along the stair-step boundary of the periodic table that exhibit properties intermediate between metals and nonmetals.

Alkali Metals

The highly reactive metallic elements belonging to Group 1 (1A) of the periodic table, excluding hydrogen.

Alkaline Earth Metals

The reactive metallic elements belonging to Group 2 (2A) of the periodic table.

Coinage Metals

The metallic elements belonging to Group 11 (1B) of the periodic table, including copper, silver, and gold.

Halogens

The reactive nonmetal elements located in Group 17 (7A) of the periodic table.

Noble Gases

The elements located in Group 18 (8A) of the periodic table that are mostly non-reactive due to having stable electron configurations.

Transition Elements

Elements located in Groups 3 through 12 (B groups) on the periodic table, which frequently form multiple cations with different charges.

Inner Transition Elements

The lanthanoids and actinoids, positioned below the main body of the periodic table.

Proton

A subatomic particle located in the nucleus of an atom carrying a positive ($+1$) charge.

Neutron

An electrically neutral subatomic particle residing in the nucleus of an atom.

Electron

A negatively charged ($-1$) subatomic particle orbiting the nucleus with negligible mass relative to protons and neutrons.

Atomic Number ($Z$)

The number of protons in the nucleus of an atom, which uniquely identifies the chemical element.

Mass Number ($A$)

The whole-number sum of protons and neutrons in the nucleus of an atom.

Nuclide Symbol

A symbolic representation of an atom showing the element symbol preceded by the mass number ($A$) as a superscript and atomic number ($Z$) as a subscript.

Isotopes

Atoms of the same element containing the same number of protons but different numbers of neutrons.

Atomic Mass Unit (amu)

A unit of mass defined as exactly $\frac{1}{12}$ the mass of a single neutral $^{12}\text{C}$ atom ($1\,\text{amu} = 1.6605 \times 10^{-27}\,\text{kg}$).

Atomic Weight (AW)

The weighted average atomic mass of all naturally occurring isotopes of an element, as listed on the periodic table.

Ion

An atom or group of atoms that carries a net electrical charge due to the loss or gain of one or more electrons.

Anion

A negatively charged ion formed when an atom or molecule gains electrons.

Cation

A positively charged ion formed when an atom or molecule loses electrons.

Chemical Formula

A representation using elemental symbols (letters) and subscripts (numbers) to show the types and proportions of atoms or ions present in a compound.

Covalent Compound

A compound composed of two or more nonmetals bound together by shared electrons, forming discrete molecules with no net charge.

Diatomic Elements

Seven elements ($\text{H}_2$, $\text{N}_2$, $\text{O}_2$, $\text{F}_2$, $\text{Cl}_2$, $\text{Br}_2$, $\text{I}_2$) that exist naturally as two-atom molecules in their elemental forms under normal conditions.

Molecular Formula

A chemical formula that specifies the actual number of atoms of each element in a single molecule of a compound.

Structural Formula

A visual diagram showing how atoms are connected and bonded to each other within a molecule.

Binary Covalent Compound

A molecular compound composed of exactly two different nonmetal elements.

Ionic Compound

A neutral chemical compound composed of cations and anions held together by electrostatic forces in a three-dimensional lattice structure.

Formula Unit

The simplest electrically neutral repeating ratio of cations and anions in an ionic compound's crystal lattice.

Polyatomic Ion

A charged species consisting of two or more covalently bonded atoms that function as a single ionic unit.

Oxyanion

A polyatomic anion composed of a central nonmetal element bonded to one or more oxygen atoms.

Hydrate

An ionic compound that incorporates a specific ratio of water molecules (waters of hydration) within its solid crystal structure.

Anhydrous Form

The dry ionic compound remaining after all waters of hydration have been driven off from a hydrate by heating.

Binary Acid

An acid consisting of hydrogen combined with a single monatomic anion (e.g., $\text{HCl}$).

Oxyacid

An acid consisting of hydrogen bonded to a polyatomic oxyanion (e.g., $\text{H}_2\text{SO}_4$).

Monoprotic Acid

An acid containing only one ionizable hydrogen atom per molecule.

Polyprotic Acid

An acid containing two or more ionizable hydrogen atoms per molecule.

Mole (mol)

The SI base unit for amount of substance, defined as containing exactly $6.02214076 \times 10^{23}$ representative particles (the number of atoms in $12\,\text{g}$ of $^{12}\text{C}$).

Avogadro's Number

The number of constituent particles per mole of substance, equal to $6.022 \times 10^{23}\,\text{mol}^{-1}$.

Molar Mass

The mass in grams of one mole of a pure element or compound, expressed in units of $\text{g/mol}$.

Percent Composition

The percentage by mass of each element in a compound, calculated as $\text{wt }\% = \frac{\text{molar mass of element}}{\text{total molar mass of compound}} \times 100\%$.

Empirical Formula

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