04/14 Chemical Bonding and Molecular Structure Free Online FlashCards

What is an ionic bond?

An ionic bond is the electrostatic attraction between oppositely charged ions, usually a cation and an anion.

Why do ionic compounds conduct when molten but not solid?

Ionic compounds conduct electricity when molten or dissolved because their ions can move. As solids, their ions are fixed in the crystal lattice.

What is a covalent bond?

A covalent bond forms when atoms share one or more pairs of electrons. Covalent compounds commonly consist of discrete molecules made from nonmetals.

How are total Lewis-structure valence electrons counted?

For a species, add the valence electrons of all atoms, add one electron per negative charge, and subtract one per positive charge.

What is the formal-charge formula?

Formal charge is FC = V − (N + ½B), where V is atomic valence electrons, N is nonbonding electrons, and B is bonding electrons.

What does resonance represent?

Resonance structures have the same atomic connectivity but different electron placements. The actual species is a resonance hybrid with delocalized electrons.

How does VSEPR count electron regions?

In VSEPR, each single bond, multiple bond, or lone pair counts as one electron region around the central atom.

What is the molecular geometry of NH3?

NH3 has a tetrahedral electron-domain geometry and a trigonal-pyramidal molecular geometry because nitrogen has three bonds and one lone pair.

Why is H2O bent?

H2O is bent, with two bonding regions and two lone-pair regions around oxygen. Its bond angle is approximately 104.5°.

Why is CO2 nonpolar despite polar bonds?

CO2 is nonpolar overall: its polar C=O bond dipoles point in opposite directions and cancel because the molecule is linear.

What equation relates dipole moment to charge separation?

The dipole moment is approximately μ = Qr, where Q is the magnitude of separated charge and r is the charge-separation distance.

How is molecular-orbital bond order calculated?

MO bond order = (Nb − Na)/2, where Nb is the number of bonding electrons and Na is the number of antibonding electrons.