Organic Chemistry Chapter 1: Review of General Chemistry: Electrons, Bonds, and Molecular Properties

A set of Q&A style flashcards covering core concepts from the lecture notes on electrons, bonds, orbitals, and molecular properties.

What is the focus of Organic Chemistry?

The study of carbon-containing molecules and their reactions, with emphasis on how electrons move during bonds and reactions.

What is the Aufbau Principle?

Electrons are assigned to shells and subshells in order of increasing energy to minimize the atom’s total energy.

What is the Pauli Exclusion Principle?

No two electrons in an atom can have the same four quantum numbers; a maximum of two electrons per orbital with opposite spins.

Which four types of atomic orbitals are commonly discussed in introductory organic chemistry?

s, p, d, and f orbitals.

Why is noble gas notation used in electron configurations?

To simplify configurations by substituting the filled inner shells with a noble gas symbol, highlighting valence electrons.

For main-group elements, what determines the number of valence electrons?

The group number on the periodic table.

What is the Octet Rule?

Atoms tend to have eight electrons in their outer shell; bonds form by gaining, losing, or sharing electrons to achieve a stable 8-electron configuration.

Define an ionic bond.

A bond produced by the electrostatic attraction between oppositely charged ions; electrons are transferred.

Define a covalent bond.

A bond formed by sharing a pair of electrons between two atoms.

What characterizes a polar covalent bond?

A covalent bond with unequal sharing of electrons, typically with an electronegativity difference around 0.5 to 1.7.

What electronegativity difference is typically associated with ionic bonds?

Differences greater than about 1.7.

What is a bond dipole moment?

A measure of bond polarity that depends on the electronegativity difference and the bond distance.

What is electronegativity?

The ability of an atom in a molecule to attract electrons to itself, measured on scales such as Pauling’s.

What are the three main types of intermolecular forces?

Hydrogen bonding, dipole–dipole interactions, and London dispersion forces.

What is hydrogen bonding?

A strong dipole–dipole interaction where a hydrogen atom bonded to N, O, or F interacts with a lone pair on another electronegative atom.

What is protic vs. aprotic solvent?

Protic solvents can hydrogen-bond; aprotic solvents cannot form hydrogen bonds.

How do hydrogen bonds compare in strength to covalent bonds?

Hydrogen bonds are weaker than covalent bonds (about 20 times weaker).

How do you determine formal charge on an atom in a Lewis structure?

Formal charge = valence electrons owned in the structure minus electrons needed for a neutral atom; compare with the atom’s valence.

What is the ammonium ion?

NH4+.

What is the hydronium ion?

H3O+.

What are the three steps to draw a simple Lewis structure?

1) Draw atoms with valence electrons; 2) Connect atoms with shared pairs to form octets; 3) Add lone pairs as needed to satisfy octets.

What is a Lewis structure used to represent?

Valence electrons as dots around atoms, showing bonds and lone pairs.

What is the steric number and its relation to hybridization?

Steric number = number of bonded atoms plus lone pairs. 4 → sp3, 3 → sp2, 2 → sp.

What molecular geometries correspond to sp3, sp2, and sp?

sp3 → tetrahedral; sp2 → trigonal planar; sp → linear.

What are the common molecular geometries for CH4, NH3, and H2O?

CH4: tetrahedral; NH3: trigonal pyramidal; H2O: bent.

What is a sigma (σ) bond?

A bond formed by direct end-to-end overlap of orbitals along the bond axis; electron density is concentrated along the bond.

What is a pi (π) bond?

A bond formed by side-by-side overlap of p orbitals, typically overlapping above and below the bond axis (in double/triple bonds).

What is the difference between MO theory and VB theory?

Molecular Orbital (MO) theory uses delocalized orbitals over the entire molecule; Valence Bond (VB) theory uses localized overlap of atomic orbitals to form bonds.

What are HOMO and LUMO?

HOMO is the highest occupied molecular orbital; LUMO is the lowest unoccupied molecular orbital; they are key in determining reactivity.

What is a polar covalent vs an ionic bond in terms of electronegativity difference?

Polar covalent: EN difference about 0.5–1.7; Ionic: EN difference typically > ~1.7.

What is the basic purpose of the octet rule in bond formation?

Atoms gain, lose, or share electrons to achieve a stable eight-electron outer shell.

What is a simple approach to predict geometry using VSEPR?

Count the steric number (bonding + lone pairs) to predict electron-pair geometry and molecular shape (e.g., tetrahedral, trigonal planar, linear).