Chem 1212 – Liquids, Solids, Gases; Polar vs Nonpolar Flashcards

A set of Question-and-Answer flashcards covering polar vs. nonpolar bonds, molecular polarity, VSEPR geometry, and polarity of common molecules based on the provided notes.

What defines a polar bond in terms of electronegativity difference?

A bond is polar if the atoms have a significant electronegativity difference greater than 0.4, leading to a dipole moment.

What defines a nonpolar bond?

A bond is nonpolar if the atoms have the same electronegativity or a very small difference (less than 0.4), so electrons are shared evenly.

What is a dipole moment?

A separation of positive and negative charges within a bond or molecule caused by uneven electron distribution.

When is a molecule polar despite having polar bonds?

If the distribution of bond dipoles is asymmetrical, the dipoles do not cancel, resulting in a polar molecule.

How is a nonpolar organic molecule defined in this lecture?

If it contains only carbon and hydrogen (no heteroatoms), it is nonpolar.

How is an organic molecule likely polar if it contains heteroatoms?

Presence of heteroatoms (O, N, S, P, Cl, F, Br, etc.) tends to create polar bonds and a polar molecule.

How is a molecule categorized as polar or nonpolar for inorganic molecules?

Inorganic molecules are polar if the geometry is not completely symmetric with identical bonds; they are nonpolar if completely symmetric with equal bonds.

Name some molecular shapes that are nonpolar due to symmetry when all bonds are identical.

Linear, Trigonal planar, Tetrahedral, Trigonal bipyramidal, Octahedral, Square planar.

Name some shapes that are polar due to lack of symmetry.

Bent, Trigonal pyramidal, See-saw, T-shaped, Square pyramidal, or any symmetric shape with not all bonds the same.

What does electron-pair geometry refer to?

The arrangement of electron densities around the central atom based on bonding and lone pairs (AXE notation).

What does molecular geometry refer to?

The spatial arrangement of the atoms in a molecule, ignoring lone pairs.

How do you determine the electron-pair geometry and molecular geometry of a molecule?

Count the number of electron domains (bonding and lone pairs), then use VSEPR to assign electron-domain geometry and the corresponding molecular geometry based on the presence of lone pairs.

What is the molecular geometry for AX2 with no lone pairs?

Linear.

What is the molecular geometry for AX3 with one lone pair (AX3E)?

Trigonal pyramidal.

What is the molecular geometry for AX2 with two lone pairs (AX2E2)?

Bent (like water).

Is NF3 polar or nonpolar?

Polar.

Is H2S polar or nonpolar?

Polar.

Is C3H8 (propane) polar or nonpolar?

Nonpolar.

Is BF3 polar or nonpolar?

Nonpolar (trigonal planar with identical B–F bonds and symmetry).

Is ethanol (C2H5OH) polar or nonpolar?

Polar.

Is CH3Cl polar or nonpolar?

Polar.