Molecular Geometry Flashcards

Study Notes

PF3 (Lewis Structure)

PF3 consists of a phosphorus atom bonded to three fluorine atoms.
Phosphorus (P) serves as the central atom in this molecular structure.

Trigonal Pyramidal

Geometry is determined by the central phosphorus atom's four electron repulsions: three from bonding pairs and one from a lone pair.
In this geometry, the molecule exhibits a three-dimensional arrangement with a triangular base and a central lone pair above.

Electron Geometry

The central phosphorus atom should exhibit tetrahedral electron geometry due to the presence of four regions of electron density (three bonding pairs and one lone pair).
Tetrahedral geometry allows for optimal spacing between electron pairs to minimize repulsion.

Tetrahedral

The ideal bond angles in a tetrahedral geometry are approximately 109.5 degrees.
All four electron repulsions around the phosphorus are bonding pairs when considering a tetrahedral arrangement.

Linear

A linear geometry occurs when there are two bonding electron densities and no lone pairs around the central atom.
Ideal bond angles are 180 degrees.

Central Atom

The central atom in a molecule is typically the least electronegative atom, anchoring other atoms around it.

Number of Electron Densities

Represents regions around the central atom where electrons exist, which may be in the form of bonding pairs or lone pairs.
Determines the molecular geometry based on VSEPR theory.

Number of Non-bonding Electrons

Refers to the electrons that are not involved in bonding and are instead present as lone pairs on the central atom.
Affects the shape and angles of the molecular geometry.

Bent

Occurs when the central atom has four electron repulsions consisting of two bonding pairs and two lone pairs.
Results in an approximate bond angle of 104.5 degrees due to repulsion of lone pairs.

COF2 Valence Electrons

Determine total valence electrons by summing the group numbers of each atom: Carbon (4), Oxygen (6), Fluorine (7×2).
Total: 4 + 6 + 14 = 24 valence electrons for COF2.

Ionic vs Covalent Bonds

The bond type is determined by the mechanism of electron interaction: ionic bonds involve the transfer of electrons, whereas covalent bonds involve the sharing of electrons.

Stability of Molecules and Ions

Molecules and ions achieve maximum stability when adhering to the octet rule, having eight electrons in their valence shell.

Valence Shell Electron-Pair Repulsion (VSEPR)

A theory used to predict molecular geometry based on repulsion between electron pairs around a central atom.
Helps visualize and deduce the shape of molecules and their bond angles.

Description

Test your understanding of molecular geometry with these flashcards focused on PF3 and trigonal pyramidal structures. Each card provides key definitions and descriptions to help reinforce your knowledge of Lewis structures and electron geometry.