Chemistry Lecture Notes: Bonding, Orbitals, Structures, and Intermolecular Forces

A comprehensive set of QA flashcards covering key concepts from bonding, orbitals, molecular structure, resonance, and intermolecular forces from the notes.

What are inorganic compounds lacking carbon atoms?

Compounds that do not contain carbon atoms.

What are constitutional isomers?

Compounds with the same molecular formula but different connectivity.

What are organic compounds?

Compounds containing carbon atoms.

What is a covalent bond?

A bond formed when two atoms share a pair of electrons.

What are Lewis structures?

A drawing style that emphasizes valence electrons and lone pairs.

What does it mean for an element to be divalent?

It forms two bonds.

What is a molecular formula?

The number and types of atoms in a compound, such as C2H6O.

What is a lone pair?

A pair of unshared, or nonbonding, electrons.

What does it mean for an element to be monovalent?

It forms one bond.

What is the octet rule?

Second-row elements tend to form eight electrons in the valence shell.

What are valence electrons?

Electrons in the outermost electron shell.

How many valence electrons do group 7A elements have?

7 valence electrons.

What is electronegativity?

The ability of an atom to attract electrons.

What does trivalent mean?

An element that forms three bonds.

What does tetravalent mean?

An element that forms four bonds.

What is formal charge?

A charge assigned to an atom based on its valence electron count.

What is an ionic bond?

Bond formed by electrostatic attraction between oppositely charged ions.

What are electrostatic potential maps?

Three-dimensional images used to visualize partial charges in a compound.

What is a nonpolar covalent bond?

A bond with electronegativity difference less than 0.5, with no partial charges.

What does degenerate mean in orbital theory?

Orbitals with the same energy.

What is the Aufbau principle?

Electrons fill the lowest energy orbitals first.

What are bond-line structures?

A common organic drawing style where most C and many H atoms are not drawn.

What is an atomic orbital?

A 3D region in space where electron density is likely.

What is a polar covalent bond?

A bond with electronegativity difference between 0.5 and 1.7, creating partial charges.

What is electron density?

The probability distribution of finding an electron in space.

What is Hund's rule?

One electron goes into each degenerate orbital before any pairing occurs.

What is the Pauli exclusion principle?

An orbital can hold at most two electrons with opposite spins.

What is a node in atomic/molecular orbitals?

A location where the wavefunction value is zero.

What is quantum mechanics?

A mathematical framework describing electrons with wave-like properties.

What is a wave equation?

An equation describing the energy of an electron in a proton's electric field.

What are wavefunctions?

Solutions to the wave equation corresponding to allowed energy levels.

What is the HOMO?

The highest occupied molecular orbital.

What is an antibonding MO?

A high-energy MO from destructive interference between atomic orbitals.

What is a sigma (σ) bond?

A bond with circular symmetry about the bond axis, formed by end-to-end overlap.

What is a bonding MO?

A low-energy MO from constructive interference between atomic orbitals.

What is constructive interference?

When waves combine to produce a larger amplitude.

What is valence bond theory?

A theory describing bonds as localized electron pairs shared between atoms.

What is molecular orbital (MO) theory?

A theory describing bonding in terms of molecular orbitals spanning the whole molecule.

What is the LUMO?

The lowest unoccupied molecular orbital.

What are sp hybrid orbitals?

Two hybrid orbitals formed by mixing one s and one p orbital.

What is a pi (π) bond?

A bond formed from side-by-side overlap of adjacent p orbitals.

What is s-character in hybrid orbitals?

The percentage of a hybrid orbital derived from s orbitals.

What is the linear geometry?

A three-atom arrangement with a bond angle of 180 degrees.

What is the bent geometry?

A three-atom arrangement that is nonlinear.

What are sp2 hybrid orbitals?

Three hybrid orbitals formed from one s and two p orbitals.

What is the steric number?

The total number of electron pairs (bonds plus lone pairs) around an atom.

What is the tetrahedral geometry?

An atom with four bonds arranged at 109.5 degrees.

What is trigonal planar geometry?

An atom with three groups in a plane arranged 120 degrees apart.

What is VSEPR theory?

Valence shell electron pair repulsion theory used to predict molecular geometry.

What is trigonal pyramidal geometry?

A geometry with one lone pair and a steric number of four.

What is the Debye unit used for?

A unit of dipole moment (1 Debye = 10^-18 esu·cm).

What is a molecular dipole moment?

The vector sum of the individual dipole moments in a molecule.

What are intermolecular forces?

Attractive forces between molecules.

What is a dipole moment (μ)?

μ = δ × d, the product of charge separation and its distance.

What is a hydrogen bond?

A strong dipole-dipole interaction between H attached to O or N and a lone pair on an electronegative atom.

What are dipole-dipole interactions?

Attractions between permanent dipoles.

What are London dispersion forces?

Weak attractions from transient dipoles, important in nonpolar molecules.

What does hydrophilic mean?

A polar group that interacts favorably with water.

What does miscible mean?

Two liquids that can mix in any proportion.

What does insoluble mean?

Not soluble in a given solvent.

What is a solute?

The substance dissolved in a solvent.

What is a condensed structure?

A drawing where bonds are not all shown; groups are clustered.

What is a Haworth projection?

A drawing style for substituted cycloalkanes showing substituent positions above or below the ring.

What is a functional group?

A characteristic group of atoms with predictable chemical behavior.

What are partially condensed structures?

A drawing style where CH bonds are not drawn explicitly but other bonds are.

What are Fischer projections?

A projection method used for molecules with multiple chiral centers, especially carbohydrates.

What are heteroatoms?

Atoms other than carbon and hydrogen.

What is the chair conformation?

The lowest-energy conformation of cyclohexane with staggered hydrogens.

What is delocalization?

Spread of a charge or lone pair through resonance.

What is resonance?

A method to account for the inadequacy of bond-line drawings by using multiple structures.

What are resonance structures?

A series of contributing structures that describe a molecule.

What does delocalized mean?

Charge or lone pair spread over two or more atoms.

What is a resonance hybrid?

The actual structure shown as a blend of resonance forms.

What does conjugated mean?

Two pi bonds separated by exactly one sigma bond.

What is a vinylic position?

A carbon atom of a C=C double bond or a group attached to such a carbon.

What is an allylic position?

Positions adjacent to the vinylic positions of a C=C double bond.

What is resonance stabilization?

Stabilization due to delocalization of electrons through resonance.

What are curved arrows?

Arrow symbols used to show electron movement in resonance and mechanisms.

What is a dash in bond-line structures?

A bond going behind the page.

What is a localized lone pair?

A lone pair not participating in resonance.

What is a wedge in bond-line structures?

A group coming out of the page.

What is sp3 hybridization?

Hybridization with four regions of electron density (four sigma bonds); approximately 25% s-character.

What is sp2 hybridization?

Hybridization with three regions of electron density; about 33% s-character.

What is sp hybridization?

Hybridization with two regions of electron density; about 50% s-character.

How many regions correspond to sp3, sp2, and sp hybridizations?

sp3 = 4 regions, sp2 = 3 regions, sp = 2 regions.

What is the steric number equation?

Steric Number (SN) = number of sigma bonds + number of lone pairs.