General Chemistry: Atomic Structure, Periodic Trends, Chemical Bonding, and Molecular Geometry

Comprehensive vocabulary flashcards covering quantum mechanics, atomic orbitals, electron configurations, periodic trends, chemical bonding models, and VSEPR/MO theory.

antibonding orbital

A higher energy molecular orbital resulting from the subtractive combination of atomic orbitals, designated by *.

bent

A molecular geometry associated with three electron domains with one lone pair, or four electron domains with two lone pairs.

bond order

Measure of the stability of the molecule, calculated from the MO diagram.

bonding orbital

Lower energy molecular orbital resulting from the additive combination of atomic orbitals.

conformation

Various shapes possible for larger molecules due to rotation around single bonds.

constructive interference

Waves combine in phase to increase peaks and decrease troughs.

coordinate covalent bonds

Covalent bond in which both electrons in the shared pair are supplied by one of the atoms.

destructive interference

Waves combine out of phase to cancel peaks and troughs.

diamagnetism

Very slight repulsion for a magnetic field; property of molecules with all paired electrons.

electron domain

A charge cloud around a central atom that can be any of these: lone pairs, single unshared electrons, single bond, double bond, or triple bond.

electron geometry

Shape determined by the number of electron domains.

flash point

Temperature at which vapors of a liquid fuel can be ignited.

hybrid orbitals

Mathematical combinations of the standard atomic orbitals that result in maximal overlap of orbitals in bonds.

isomers

Different compounds with the same molecular formula.

linear

An electron geometry associated with two electron domains. Also a molecular geometry resulting from two bonded groups at a $180^\circ$ bond angle, which occurs with two electron domains with no lone pairs, and five electron domains with three lone pairs.

molecular dipole

Molecule with uneven electron distribution; polar molecule.

molecular geometry

Three-dimensional shape of a molecule.

molecular orbital, MO

A type of orbital resulting from the combination of atomic orbitals in a molecule.

molecular orbital, MO, diagram

Similar to an atomic orbital diagram; shows the relative energy levels and electron population of the molecular orbital; used to predict properties.

molecular orbital, MO, theory

Theory that explains bonding by the combination of atomic orbitals to form bonding molecular orbitals and antibonding molecular orbitals.

nonbonding orbitals

Orbitals occupied by lone pairs in MO diagrams.

nonpolar molecule

Molecule with symmetric electron distribution; no dipole.

octahedral

An electron geometry associated with six electron domains. Also a molecular geometry if all six domains are bonded groups; symmetrical shape consisting of eight triangular faces and $90^\circ$ and $180^\circ$ bond angles.

paramagnetism

Weak attraction to a magnetic field; property of molecules with unpaired electrons.

pi, $\pi$, bond

Bond formed by side-on overlap of unhybridized $p$ orbitals above and below the internuclear axis; found in double and triple bonds.

polar molecule

A molecule with asymmetric electron distribution; molecular dipole.

see-saw

A molecular geometry associated with five electron domains with one lone pair.

sigma, $\sigma$, bond

A type of bond formed by head-to-head overlap of orbitals along the internuclear axis; found in all covalent bonds.

$sp$ hybrid orbitals

Hybrid orbitals formed from one $s$ orbital and one $p$ orbital; associated with linear electron geometry.

$sp^2$ hybrid orbitals

Hybrid orbitals formed from one $s$ orbital and two $p$ orbitals; associated with trigonal planar electron geometry.

$sp^3$ hybrid orbitals

Hybrid orbitals formed from one $s$ orbital and three $p$ orbitals; associated with tetrahedral electron geometry.

square planar

A molecular geometry associated with six electron domains with two lone pairs.

square pyramidal

A molecular geometry associated with six electron domains with one lone pair.

tetrahedral

An electron geometry associated with four electron domains. Also a molecular geometry if all four electron domains are bonded groups; having the shape of a tetrahedron; $109.5^\circ$ bond angles.

tetrahedron

Symmetric three-dimensional shape consisting of four equilateral triangular faces.

trigonal bipyramidal

An electron geometry associated with five electron domains consisting of two three-sided pyramids sharing a base. Also a molecular geometry if all five electron domains are bonded groups; $90^\circ$, $120^\circ$, and $180^\circ$ bond angles.

trigonal planar

An electron geometry associated with three electron domains. Also a molecular geometry if all three electron domains are bonded groups; $120^\circ$ bond angles.

trigonal pyramidal

Molecular geometry associated with four electron domains with one lone pair; a three-sided pyramid.

T-shaped

A molecular geometry associated with five electron domains with two lone pairs.

valence bond, VB, theory

Theory that explains bonding by the overlap of atomic orbitals and hybridization of atomic orbitals.

valence shell electron pair repulsion, VSEPR, model

Model that uses the number of electron domains around a central atom to predict the most stable shape occupied by the domain due to repulsion.

bond enthalpy

The enthalpy change, $\Delta H$, associated with breaking a specific bond in $1\,\text{mol}$ of gaseous molecules.

debye (D)

The unit of dipole moment measurement.

delocalized bond

Multiple bonds in resonance structures that are spread out over more than one location.

dipole

A bond that exhibits separate areas of opposite charge of equal magnitude.

dipole moment, $\mu$

Measurable quantity related to the magnitude of the charge, $q$, and the distance between the charges, $r$, and is reported in debye units, D.

double bond

A bond consisting of two atoms sharing two pairs of electrons and shown as two short lines in Lewis structures.

duet rule

Hydrogen forms only one bond in covalent compounds, filling its $1s$ valence shell.

electronegativity

Measure of the electron-attracting ability of an atom in a covalent bond.

expanded valence shell

Elements from periods 3–7 can form more than four bonds when making compounds, expanding beyond the octet rule.

formal charge

Compares an atom’s electron status within a molecule to the number of valence electrons of the atom.

ionic character

Measured as percent comparing the observed charge separation to 100% charge separation.

Lewis-dot symbol

The symbol for an element surrounded by dots representing its valence electrons.

Lewis structure

Diagram of a molecule or polyatomic ion showing shared pairs or bonds as straight lines and unshared or lone pairs as dots.

lone pair

Unshared pairs of electrons in molecules or polyatomic ions.

octet rule

Atoms gain, lose, or share electrons to achieve a stable noble-gas electron configuration, (eight electrons), for elements in period 2 especially and, with expanded valence exceptions, for elements in periods 3–7.

polar covalent bond

A bond resulting from unequal sharing of electrons and characterized by a separation of partial charges.

polyatomic ion

A charged group of atoms connected by covalent bonds.

radical

A molecule or ion with an unpaired electron in its Lewis structure.

resonance

The property of having resonance structures.

resonance hybrid

A single structure with delocalized bonds that represents the average of the separate resonance structures.

resonance structures

Multiple, equivalent, or close-to-equivalent Lewis structures for a molecule or ion that differ only in the placement of multiple bonds and lone pairs.

single bond

A bond consisting of two atoms sharing one pair of electrons and shown as a short, straight line in Lewis structures.

triple bond

A bond consisting of two atoms sharing three pairs of electrons and shown as three short lines in Lewis structures.

bond energy, BE

The energy needed to break a mole of a specific type of bond; also called bond enthalpy.

Born–Haber cycle

A thermodynamic cycle that uses Hess’s law, ionization energy, electron affinity, and the energies of other processes to calculate the lattice energy of an ionic compound.

core electrons

The electrons in the shells of an atom or ion that are lower in energy (principal quantum number or lower) than the highest occupied shell ($n$); all electrons that are not valence electrons.

effective nuclear charge, $Z_{\text{eff}}$

The net positive charge from the nucleus that a valence electron experiences.

electron affinity, EA

The energy liberated when an electron is added to a gaseous atom to form a gaseous anion.

electrostatic

Pertaining to the forces of attraction or repulsion in charged species.

electrostatic attraction

The forces of attraction between oppositely charged species.

ionization energy, IE

The energy required to remove an electron from a gaseous atom to produce a gaseous cation.

lattice energy

The energy released when gas-phase ions combine to form a solid ionic compound.

periodicity

The tendency to recur at intervals.

second ionization energy

The energy required to remove an electron from the gaseous ion.

Slater’s rules

A set of rules that provides a numerical value for the shielding constant $S$ when calculating effective nuclear charge.

sublimation

The phase change from solid to gas.

third ionization energy

The energy required to remove an electron from the gaseous ion.

valence electrons

The electrons in the highest occupied shell (principal quantum number $n$) of an atom or ion.

absorbance spectrum

The specific wavelengths of light that are absorbed by an atom when it gains energy.

angular momentum quantum number, $\ell$

The number that corresponds to a particular subshell within the atom.

aufbau principle

When filling the subshells of an atom with electrons, the electrons always fill the lowest-energy subshell available before any electrons are added to higher-energy subshells.

Bohr model

The first model of the atom to propose that electrons in atoms were in definite energy levels.

degenerate

Having the same energy.

diamagnetic

Very slight repulsion from a magnetic field; a property of substances with all paired electrons.

discrete energy level

An atomic energy level that has specific energy.

electromagnetic radiation

A collective term for light of all wavelengths in the electromagnetic spectrum.

electromagnetic spectrum

The complete collection of electromagnetic waves, including visible light, infrared, ultraviolet, X-rays, gamma rays, and microwaves.

electron configuration

The arrangement of the electrons in the shells and subshells of an atom, or the shorthand notation used to represent this arrangement.

emission spectrum

The specific wavelengths of light that are emitted by an atom when it releases stored energy.

excited state

The state of an atom that has more energy than does its lowest energy state.

frequency, $\nu$

The number of times a wave crest passes a certain point per second.

ground state

The lowest energy state of the set of electrons in an atom.

Hund’s rule

The electrons in a partially filled subshell in an atom spread out to occupy the orbitals singly as much as possible.

isoelectronic

Having the same electron configuration.

light

In general, any electromagnetic radiation; specifically, visible light—the wave motion that is visible to the human eye.

light absorption

The process in which the energy of certain wavelengths of light increases the energy of electrons in atoms.

light emission

The process in which light of specific wavelengths is produced when electrons in atoms fall to lower energy levels.

line spectrum

The emission spectrum of an element when it appears as a series of discrete lines.

lobe

One portion of an atomic orbital.