Molecular Structure and Bonding

Flashcards covering molecular geometry, the EPA model, and electronegativity concepts.

Tetrahedral

The shape that results from the repulsion of four electron pairs around a central atom, leading to bond angles of 109.5 degrees, as seen in methane (CH4).

Pyramidal

The molecular geometry of a molecule like ammonia (NH3) where there are three bonding pairs and one lone pair around the central atom.

Bent

The shape of a molecule like water (H2O) which has two bonding pairs and two lone pairs of electrons around the central oxygen atom.

Linear

Describes a molecule with atoms arranged in a straight line, such as carbon dioxide (CO2).

EPA Model

Electron Pair Repulsion model developed by Ronald J. Gillespie in 1957 which posits that electron pairs around an atom repel each other and arrange themselves to maximize the distance between them.

Non-bonding electron pairs

Also known as lone pairs, these electron pairs are not involved in bonding and exert a greater repulsive force than bonding pairs, influencing molecular geometry.

Trigonal Planar

The molecular geometry around an atom bonded to three other atoms with no lone pairs, resulting in bond angles of 120 degrees.

Wedge-Dash Notation

A method of depicting three-dimensional molecular structures where solid wedges represent bonds projecting out of the plane, dashed wedges represent bonds going into the plane, and straight lines represent bonds in the plane.

Electronegativity

The ability of an atom to attract bonding electrons in a chemical bond.

Polar Covalent Bond

A covalent bond in which the electrons are unequally shared between the atoms, resulting in a partial positive charge (δ+) on one atom and a partial negative charge (δ−) on the other.

Dipole

A molecule with a separation of charge, resulting in a positive end and a negative end.

ΔEN

The difference in electronegativity between two bonded atoms, which indicates the polarity of the bond.