Molecular Geometry and VSEPR Theory

Vocabulary flashcards covering VSEPR theory, molecular geometry shapes, AXE notations, electron group counts, bond angles, and molecular examples.

VSEPR Theory

Valence Shell Electron Pair Repulsion theory; a model stating that electron-group repulsion around a central atom determines molecular shape.

AXE Notation

A standard system where A represents the central atom, X represents bonding atoms/groups, and E represents lone electron pairs on the central atom.

Linear Geometry ($AX_2$)

A molecular geometry characterized by 2 electron groups, 0 lone pairs, and bond angles of $180^\circ$ (e.g., $CO_2$, $HCN$).

Trigonal Planar Geometry ($AX_3$)

A molecular geometry characterized by 3 electron groups, 0 lone pairs, and bond angles of $120^\circ$ (e.g., $BF_3$, $SO_3$).

Bent Geometry ($AX_2E$)

A molecular geometry with 3 electron groups (2 bonding groups, 1 lone pair) and bond angles of $<120^\circ$ (e.g., $SO_2$, $O_3$).

Tetrahedral Geometry ($AX_4$)

A molecular geometry characterized by 4 electron groups, 0 lone pairs, and bond angles of $109.5^\circ$ (e.g., $CH_4$, $CCl_4$).

Trigonal Pyramidal Geometry ($AX_3E$)

A molecular geometry with 4 electron groups (3 bonding groups, 1 lone pair) and bond angles of $\sim 107^\circ$ (e.g., $NH_3$, $PCl_3$).

Bent Geometry ($AX_2E_2$)

A molecular geometry with 4 electron groups (2 bonding groups, 2 lone pairs) and bond angles of $\sim 104.5^\circ$ (e.g., $H_2O$, $OF_2$).

Trigonal Bipyramidal Geometry ($AX_5$)

A molecular geometry characterized by 5 electron groups, 0 lone pairs, and bond angles of $90^\circ$, $120^\circ$, and $180^\circ$ (e.g., $PCl_5$, $PF_5$).

Seesaw Geometry ($AX_4E$)

A molecular geometry with 5 electron groups (4 bonding groups, 1 lone pair) and bond angles of $<90^\circ$, $<120^\circ$, and $180^\circ$ (e.g., $SF_4$, $TeCl_4$).

T-shaped Geometry ($AX_3E_2$)

A molecular geometry with 5 electron groups (3 bonding groups, 2 lone pairs) and bond angles of $\sim 90^\circ$ and $180^\circ$ (e.g., $ClF_3$, $BrF_3$).

Linear Geometry ($AX_2E_3$)

A molecular geometry with 5 electron groups (2 bonding groups, 3 lone pairs) and bond angles of $180^\circ$ (e.g., $XeF_2$, $I_3^-$).

Octahedral Geometry ($AX_6$)

A molecular geometry characterized by 6 electron groups, 0 lone pairs, and bond angles of $90^\circ$ and $180^\circ$ (e.g., $SF_6$, $[PF_6]^-$).

Square Planar Geometry ($AX_4E_2$)

A molecular geometry with 6 electron groups (4 bonding groups, 2 lone pairs) and bond angles of $90^\circ$ and $180^\circ$ (e.g., $XeF_4$, $[PtCl_4]^{2-}$).

Carbon Dioxide ($CO_2$)

A linear molecule with AXE notation $AX_2$, 2 electron groups, and a bond angle of $180^\circ$.

Hydrogen Cyanide ($HCN$)

A linear molecule with AXE notation $AX_2$, 2 electron groups, and a bond angle of $180^\circ$.

Boron Trifluoride ($BF_3$)

A trigonal planar molecule with AXE notation $AX_3$, 3 electron groups, and bond angles of $120^\circ$.

Sulfur Trioxide ($SO_3$)

A trigonal planar molecule with AXE notation $AX_3$, 3 electron groups, and bond angles of $120^\circ$.

Sulfur Dioxide ($SO_2$)

A bent molecule with AXE notation $AX_2E$, 3 electron groups, and bond angles of $<120^\circ$.

Ozone ($O_3$)

A bent molecule with AXE notation $AX_2E$, 3 electron groups, and bond angles of $<120^\circ$.

Methane ($CH_4$)

A tetrahedral molecule with AXE notation $AX_4$, 4 electron groups, and bond angles of $109.5^\circ$.

Carbon Tetrachloride ($CCl_4$)

A tetrahedral molecule with AXE notation $AX_4$, 4 electron groups, and bond angles of $109.5^\circ$.

Ammonia ($NH_3$)

A trigonal pyramidal molecule with AXE notation $AX_3E$, 4 electron groups, and bond angles of $\sim 107^\circ$.

Phosphorus Trichloride ($PCl_3$)

A trigonal pyramidal molecule with AXE notation $AX_3E$, 4 electron groups, and bond angles of $\sim 107^\circ$.

Water ($H_2O$)

A bent molecule with AXE notation $AX_2E_2$, 4 electron groups, and bond angles of $\sim 104.5^\circ$.

Oxygen Difluoride ($OF_2$)

A bent molecule with AXE notation $AX_2E_2$, 4 electron groups, and bond angles of $\sim 104.5^\circ$.

Phosphorus Pentachloride ($PCl_5$)

A trigonal bipyramidal molecule with AXE notation $AX_5$, 5 electron groups, and bond angles of $90^\circ$, $120^\circ$, and $180^\circ$.

Phosphorus Pentafluoride ($PF_5$)

A trigonal bipyramidal molecule with AXE notation $AX_5$, 5 electron groups, and bond angles of $90^\circ$, $120^\circ$, and $180^\circ$.

Sulfur Tetrafluoride ($SF_4$)

A seesaw-shaped molecule with AXE notation $AX_4E$, 5 electron groups, and bond angles of $<90^\circ$, $<120^\circ$, and $180^\circ$.

Tellurium Tetrachloride ($TeCl_4$)

A seesaw-shaped molecule with AXE notation $AX_4E$, 5 electron groups, and bond angles of $<90^\circ$, $<120^\circ$, and $180^\circ$.

Chlorine Trifluoride ($ClF_3$)

A T-shaped molecule with AXE notation $AX_3E_2$, 5 electron groups, and bond angles of $\sim 90^\circ$ and $180^\circ$.

Bromine Trifluoride ($BrF_3$)

A T-shaped molecule with AXE notation $AX_3E_2$, 5 electron groups, and bond angles of $\sim 90^\circ$ and $180^\circ$.

Xenon Difluoride ($XeF_2$)

A linear molecule with AXE notation $AX_2E_3$, 5 electron groups, and a bond angle of $180^\circ$.

Triiodide Ion ($I_3^-$)

A linear polyatomic ion with AXE notation $AX_2E_3$, 5 electron groups, and a bond angle of $180^\circ$.

Sulfur Hexafluoride ($SF_6$)

An octahedral molecule with AXE notation $AX_6$, 6 electron groups, and bond angles of $90^\circ$ and $180^\circ$.

Hexafluorophosphate Ion ($[PF_6]^-$)

An octahedral polyatomic ion with AXE notation $AX_6$, 6 electron groups, and bond angles of $90^\circ$ and $180^\circ$.

Xenon Tetrafluoride ($XeF_4$)

A square planar molecule with AXE notation $AX_4E_2$, 6 electron groups, and bond angles of $90^\circ$ and $180^\circ$.

Tetrachloroplatinate(II) Ion ($[PtCl_4]^{2-}$)

A square planar polyatomic ion with AXE notation $AX_4E_2$, 6 electron groups, and bond angles of $90^\circ$ and $180^\circ$.