Chem_5ed Chap 8 Test

Which of the following are exceptions to the valence bond theory?

• it doesn't explain molecular resonance

• it doesn't explain instances when the octet rule does not work

• it doesn't work for molecules with odd number of electrons, electron deficiency, or hypervalent molecules

• all of these are exceptions to valence bond theory

What is the major limitation of Lewis structures in depicting molecules?

• They do not show 3-dimensional shape

• They are always used to predict reaction mechanisms.
• They show all possible resonance structures accurately.
• They provide a complete picture of electron distribution.

Answer explanation

They are also more limited in representation of a molecule's chemical and physical properties

Which of the following molecular shapes must always be polar

• bent

• pyramidal

• tetrahedral

• linear

• trigonal planar

How many polar bonds are found in SBr₂? Is the whole molecule polar or nonpolar?

• no polar bonds; nonpolar

• 1 polar bond; polar

• 2 polar bonds; nonpolar

• 2 polar bonds; polar

What makes a bond polar?

• a difference in electronegativity between the bonded atoms.

• if it contains a metal and a non-metal.

• if it has a symmetrical shape.

• A bond is polar due to equal sharing of electrons.

What shape would be formed by COBr₂

• Trigonal planar
• pyramidal

• Linear
• Tetrahedral
• bent

What is the only possible shape for a molecule consisting of only 2 atoms such as HF or Cl₂

• Bent
• Tetrahedral
• Trigonal planar
• Linear

What makes a molecule polar?

• A molecule is polar if it has a symmetrical shape.
• A molecule is polar if it contains only carbon atoms.
• A molecule is polar if it has a high molecular weight.
• when it has distinct positive and negative partial charges

What term describes the process by which new kinds of orbitals of equal energy are formed from a combination of orbitals of different energies?

• Hybridization
• Resonance
• Electron Affinity
• Ionization

What theory of bonding makes the assumption that molecular shapes are largely determined by the repulsion of regions of electron concentration?

• Molecular Orbital Theory
• Hybridization Theory
• valence shell electron pair repulsion theory

• Valence Bond Theory