OCHEM Unit 1 Exam

Chapter 1 and 2 Vocab

Node

Region of zero electron density

Valence shell

An atom’s outermost shell

Ionic bond

Ions that are held together by the electrical attraction of unlike charges

Covalent bond

A shared-electron bond

Electron-dot structures

A simple way of indicating covalent bonds in molecules in which the valence-shell electrons of an atom are represented as dots

Kekulé structures

A simple way of indicating covalent bonds in which the two-electron covalent bonds are indicated as lines drawn between atoms

Lone-pair electrons

Valence electrons that are not used for bonding that remain as dots in structures

Valence Bond (VB) Theory

States a covalent bond forms when two atoms approach each other closely and a singly occupied orbital on one atom overlaps a singly occupied orbital on the other atom

Sigma bond

Bonds that are formed by the head-on overlap of two atomic orbitals along a line drawn between the nuclei

Sp³ hybrid orbital

Tetrahedrally oriented orbital formed by the mixing of one s atomic orbital and three p atomic orbitals to create four equivalent new orbitals

Sp² hybrid orbital

Forms when one s orbital and two p orbitals mix to create three equivalent hybrid orbitals

Pi bond

A covalent bond formed through the lateral overlap of unhybridized atomic p orbitals on adjacent atoms

Sp hybrid

When one s orbital and one p orbital on an atom mix to form two equivalent sp hybrid orbitals

Molecular orbital (MO) theory

Describes covalent bond formation as atomic orbitals belonging to the entire molecule rather than an individual atom

Condensed structures

When carbon-carbon and carbon-hydrogen single bonds aren’t shown and understood to be there.

Polar covalent bonds

The bonding electrons are attracted more strongly by one atom than the other so that electron distribution between atoms is not symmetrical

Electronegativity (EN)

Intrinsic ability of an atom to attract the shared electrons in a covalent bond

Electrostatic potential maps

Figures that show charge distributions in molecules using colors to indicate electron-rich and electron-poor

Inductive effect

The shifting of electrons in a sigma bond in response to the electronegativity of nearby atoms

Dipole moment (𝜇)

A measure of the separation of positive and negative charges in a system

Resonance forms

Alternative Lewis structures that show different placements of electrons in a molecule

Resonance hybrid

The single, true chemical structure of a molecule or ion that is an average of multiple valid contributing Lewis structures

Bronsted-Lowry acid

A substance that donates a hydrogen ion

Bronsted-Lowry base

A substance that accepts a hydrogen ion

Acidity constant (Ka)

The exact strength of a given acid in water solution

pKa

Negative common logarithm of Ka

Lewis acid

Substance that accepts an electron pair

Lewis base

A substance that donates an electron pair

Dispersion forces

Force that occurs between all neighboring molecules and arise because the electron distribution within molecules is constantly changing

Electron configuration

Lewis line structure

Nonbonding electron

Orbital

Organic chemistry

Skeletal structure

Conjugate acid

Conjugate base

Formal charge

Hydrogen bond

Intermolecular force

Noncovalent interaction