4 Molecular Structure and Polarity Free Online FlashCards

What arrangement does VSEPR theory predict?

Electron-density regions around a central atom arrange themselves as far apart as possible.

How does VSEPR count a multiple bond?

Each bond counts as one region, whether it is single, double, or triple.

How do lone pairs affect molecular geometry?

Each lone pair counts as an electron-density region and affects molecular shape, but it is not included in the molecular geometry name.

How do electron-pair geometry and molecular geometry differ?

Electron-pair geometry describes all regions around the central atom; molecular geometry describes the arrangement of atoms only.

What do A, X, and E represent in AXₘEₙ?

In AXₘEₙ, A is the central atom, X represents bonded atoms, and E represents lone pairs on the central atom.

What is the molecular geometry of AX₂E₃?

AX₂E₃ has a linear molecular geometry.

Why can lone pairs reduce nearby bond angles?

Lone pairs generally repel more strongly than bonding regions, often compressing nearby bond angles.

What makes a covalent bond polar?

A covalent bond is polar when its atoms attract shared electrons unequally. The more electronegative atom is partially negative (δ−), and the other is partially positive (δ+).

How do bond dipoles determine molecular polarity?

A molecule is polar when the vector sum of its bond dipoles is nonzero; if the dipoles cancel, it is nonpolar.

Why is CO₂ nonpolar despite having polar bonds?

CO₂ is nonpolar: its linear shape places the polar C=O bond dipoles in opposite directions, so they cancel.

Why is H₂O a polar molecule?

H₂O is polar because its bent shape means the O–H bond dipoles do not cancel.

What attraction can occur between polar molecules?

Polar molecules can attract one another through dipole–dipole forces.