General Chemistry: Atomic Structure, Periodic Trends, Chemical Bonding, and Nomenclature

Comprehensive vocabulary flashcards covering electronic configurations, periodic trends, ionic and covalent bonding, molecular properties, and chemical nomenclature based on Chemistry 201 lecture notes.

Core Electrons

Electrons located in lower-energy, inner shells that do not participate in chemical bonding and shield outer valence electrons from the full nuclear charge.

Valence Electrons

Electrons in all sublevels of the highest principal energy shell ($n$) that participate in chemical bonding, are lost to form cations, or are gained to form anions.

Anomalous Electron Configurations of $\text{Cr}$ and $\text{Cu}$

Exceptions to predicted Aufbau filling where an electron is promoted from the $4s$ to the $3d$ orbital to achieve the enhanced thermodynamic stability of half-filled ($\text{Cr}: [\text{Ar}]\,3d^5\,4s^1$) or completely filled ($\text{Cu}: [\text{Ar}]\,3d^{10}\,4s^1$) $d$ subshells.

Octet Rule

The principle stating that atoms lose, gain, or share electrons in order to acquire eight valence electrons (a filled $ns$ and $np$ subshell), matching the stable electron configuration of a noble gas.

Duet Rule

The principle that hydrogen ($\text{H}$) and helium ($\text{He}$) achieve maximum stability by acquiring only two electrons to completely fill their $1s$ valence orbital.

Shielding

The electrostatic screening effect that occurs when inner core electrons block valence electrons from feeling the full attractive charge of the nucleus.

Effective Nuclear Charge ($Z^*_{\text{eff}}$)

The net positive charge experienced by an outer valence electron in a polyelectronic atom, calculated as $Z^*_{\text{eff}} = Z - \text{shielding electrons}$.

Ionization Energy ($\text{IE}$)

The energy required to completely remove an electron from an isolated, gaseous atom or ion in its ground state ($X(g) \rightarrow X^+(g) + e^-$).

Electron Affinity ($\text{EA}$)

The potential energy change associated with the addition of an electron to a gaseous atom or ion in its ground state ($X(g) + e^- \rightarrow X^-(g)$), which is an exothermic process for the first electron in nearly all neutral atoms.

Compound

A pure chemical substance composed of two or more different elements combined in a specific, fixed ratio and held together by chemical bonds.

Ionic Bonding

The electrostatic attraction that holds oppositely charged cations and anions together, typically formed when a metal atom transfers one or more electrons to a nonmetal atom.

Lattice

A rigid, regular three-dimensional array of alternating cations and anions held together by mutual electrostatic attraction.

Lattice Energy

The amount of energy required to convert one mole of a solid ionic compound into its constituent ions in the gas phase, directly proportional to ionic charge magnitudes and inversely proportional to internuclear distance ($F \propto \frac{Q_1 \cdot Q_2}{d^2}$).

Lewis Dot Symbol

A visual notation consisting of the elemental symbol surrounded by dots representing valence electrons, with up to two electrons placed on each of the four imaginary sides of the symbol.

Covalent Bond

A chemical link formed between two nonmetal atoms when they share one, two, or three pairs of valence electrons in overlapping orbital space to achieve an octet.

Potential Energy Curve of $\text{H}_2$

A potential energy diagram showing that the formation of an $\text{H}_2$ molecule reaches minimum energy ($-435\,\text{kJ/mol}$) at an internuclear distance of $75\,\text{pm}$, where attractive and repulsive forces are balanced.

Bond Dissociation Energy ($D$)

The amount of energy required to break one mole of a specific covalent bond in a gas-phase molecule into neutral fragments.

Electronegativity

A measure of the relative attractive force that a bonded atom exerts on the shared electrons within a covalent bond.

Polar Bond

A covalent bond formed between atoms of different electronegativities, causing an unequal distribution of electron density with partial negative ($\delta^-$) and partial positive ($\delta^+$) charges.

Dipole Moment ($\mu$)

A quantitative measure of net charge separation across a molecule, defined by $\mu = q \times r$ (where $q$ is charge and $r$ is distance), measured in Debye units ($1\,\text{D} = 3.34 \times 10^{-30}\,\text{C}\,\text{m}$).

Law of Definite Proportions

The chemical principle stating that different samples of a given compound always contain the same elements in the exact same proportion by mass.

Law of Multiple Proportions

The chemical principle stating that when two elements form more than one compound, the ratios of the masses of one element combining with a fixed mass of the other can be expressed in small whole numbers.

Allotropes

Two or more distinct structural molecular forms of the same chemical element in the same physical state, such as dioxygen ($\text{O}_2$) and ozone ($\text{O}_3$).

Molecular Formula

A chemical formula that specifies the exact, actual number of atoms of each element contained within a single molecule of a compound.

Empirical Formula

A chemical formula that conveys the simplest whole-number ratio of the elements present in a compound.

Alkanes

The simplest class of hydrocarbons, composed exclusively of carbon and hydrogen atoms joined entirely by single covalent bonds (such as methane, ethane, and propane).

Functional Group

A specific structural arrangement of atoms in an organic compound (such as $-OH$, $-CHO$, $-COOH$, or $-NH_2$) that largely determines the chemical reactivity of the molecule.

Polyatomic Ion

A charged chemical species composed of two or more covalently bonded atoms carrying an overall net positive or negative ionic charge.

Oxoacid

An acid containing hydrogen, oxygen, and another element that dissociates in water to yield hydrogen ions and the corresponding oxoanions, named with the suffix -ic for -ate anions and -ous for -ite anions.

Hydrate

A crystalline ionic solid containing a specific, stoichiometric ratio of water molecules trapped within its structure, such as copper(II) sulfate pentahydrate ($\text{CuSO}_4 \cdot 5\text{H}_2\text{O}$).

Anhydrous Compound

The dry, water-free chemical substance remaining after all water molecules of crystallization have been driven out of a hydrate by heating.

Molecular Mass

The total average mass of an individual molecule, expressed in atomic mass units ($\text{amu}$), calculated by summing the average atomic masses of all constituent atoms in its molecular formula.

Formula Mass

The sum of the atomic masses of the atoms in the empirical formula unit of an ionic compound, expressed in atomic mass units ($\text{amu}$).

Percent Composition by Mass

The percentage of a compound's total mass accounted for by each constituent element, calculated as $\frac{n \times \text{atomic mass of element}}{\text{molecular or formula mass of compound}} \times 100\%$.

Molar Mass ($M$)

The mass in grams of one mole ($6.022 \times 10^{23}$ particles) of an element or compound ($\text{g/mol}$), which is numerically equivalent to its atomic, molecular, or formula mass in $\text{amu}$.