VSEPR, Hybridization, and Molecular Geometry Flashcards

Flashcards covering electron and molecular geometries, hybridization states, bond angles, and specific molecular examples from the VSEPR lecture.

Electron geometry

The 3D arrangement of ALL electron regions (bonding pairs + lone pairs) around the central atom, describing the full shape of where electron density sits.

Molecular geometry

The 3D shape of a molecule based only on the positions of ATOMS; lone pairs are ignored for the visible shape.

Hybridization

The mixing of atomic orbitals ($s$, $p$, $d$) on the central atom to form new, equal-energy hybrid orbitals to explain specific geometries.

$sp$ Hybridization

Formed from $2$ electron regions, resulting in a linear electron geometry with a bond angle of $180^\text{o}$. Examples: $BeH_2$, $CO_2$, and $Ag(NH_3)_2^+$.

$sp^2$ Hybridization

Formed from $3$ electron regions with trigonal planar electron geometry ($120^\text{o}$); molecular geometries include trigonal planar ($0$ lone pairs) or bent ($1$ lone pair, $\text{~}120^\text{o}$).

$sp^3$ Hybridization

Formed from $4$ electron regions with tetrahedral electron geometry ($109.5^\text{o}$); molecular geometries include tetrahedral ($0$ LP), trigonal pyramidal ($1$ LP), or bent ($2$ LP).

$sp^3d$ Hybridization

Formed from $5$ electron regions with trigonal bipyramidal electron geometry ($90^\text{o}$, $120^\text{o}$, $180^\text{o}$); molecular geometries include trigonal bipyramidal, see-saw, T-shaped, or linear.

$sp^3d^2$ Hybridization

Formed from $6$ electron regions with octahedral electron geometry ($90^\text{o}$, $180^\text{o}$); molecular geometries include octahedral, square pyramidal, or square planar.

Equatorial positions

The positions in $sp^3d$ geometry that lone pairs ALWAYS occupy because they provide more space ($120^\text{o}$ apart) compared to axial positions ($90^\text{o}$ apart).

Lone pair compression

The phenomenon where lone pairs take up more space than bonding pairs, compressing bond angles (e.g., $sp^3$ angles decrease from $109.5^\text{o}$ in $CH_4$ to $\text{~}107^\text{o}$ in $NH_3$ and $\text{~}104.5^\text{o}$ in $H_2O$).

$CH_4$ Parameters

$sp^3$ hybridization, tetrahedral electron geometry, tetrahedral molecular geometry, $0$ lone pairs, and a bond angle of $109.5^\text{o}$.

$NH_3$ Parameters

$sp^3$ hybridization, tetrahedral electron geometry, trigonal pyramidal molecular geometry, $1$ lone pair, and a bond angle of $\text{~}107^\text{o}$.

$H_2O$ Parameters

$sp^3$ hybridization, tetrahedral electron geometry, bent molecular geometry, $2$ lone pairs, and a bond angle of $\text{~}104.5^\text{o}$.

$SF_6$ Parameters

$sp^3d^2$ hybridization, octahedral electron geometry, octahedral molecular geometry, $0$ lone pairs, and bond angles of $90^\text{o}$ and $180^\text{o}$.

$XeF_4$ Parameters

$sp^3d^2$ hybridization, octahedral electron geometry, square planar molecular geometry, $2$ lone pairs (opposite each other), and a bond angle of $90^\text{o}$.

$SeCl_4$ Parameters

$sp^3d$ hybridization, trigonal bipyramidal electron geometry, see-saw molecular geometry, $1$ lone pair (equatorial), and bond angles of $90^\text{o}$, $120^\text{o}$, and $180^\text{o}$.

$BrF_3$ Parameters

$sp^3d$ hybridization, trigonal bipyramidal electron geometry, T-shaped molecular geometry, $2$ lone pairs (both equatorial), and bond angles of $90^\text{o}$ and $180^\text{o}$.