Molecular Structures

In a molecule of methane (CH4), what is the bond angle formed by any two hydrogen atoms and the central carbon atom?

109.5 degrees

Here is the Lewis structure for hydrogen cyanide (HCN). In this molecule, the bond between the hydrogen and carbon atoms forms from the overlap of a _______ orbital from hydrogen atom and a _______ orbital from the carbon atom.

1s; sp hybrid

Structure A and Structure B are resonance structures for the formate ion. What is the best account of the number and types of bonds in this ion?

3 sigma bonds (σ) and 1 delocalized pi bond (π)

Carbon (C) and hydrogen (H) have nearly equal electronegativities. Chlorine (Cl), in contrast, is significantly more electronegative than both carbon and hydrogen. Several small molecules are made from these three elements, with carbon always as the central atom. Which molecule has the greatest dipole moment?

CH3Cl

A molecule of water (H2O) has a dipole moment that provides its oxygen atom with a slight negative charge, and its two hydrogen atoms with slight positive charges. What explains this fact? I. the difference in electronegativity between oxygen and hydrogen II. the bent shape of a water molecule III. the resonance structures of a water molecule

I and II only

Which of the following molecular geometries arise from a tetrahedral electron-domain geometry? I. tetrahedral II. trigonal pyramidal III. bent

I, II, and III

A certain molecule has at least two delocalized electrons. These electrons could come from... I. exactly one sigma bond (σ) II. two or more sigma bonds (σ) III. exactly one pi bond (π) IV. two or more pi bonds (π)

III and IV only

In which of the following molecules is each bond angle 90 degrees?

SF6

In a molecule of iodine trichloride (ICl3), an iodine atom is bonded to three chlorine atoms. Both iodine and chlorine are halogens. What is the molecular shape of iodine trichloride?

T-shaped

According to molecular orbital theory, why does diatomic helium (He2) not exist?

The bonding electrons of the molecule would equal the antibonding electrons.

The electron configuration of carbon is [He]1s22p2. When carbon forms four covalent bonds, as it does in methane (CH4), what best describes the orbitals of its valence electrons?

They become a set of four sp3 hybrid orbitals.

In this molecule, what shape is formed by connecting the nuclei of the three carbon atoms and the nitrogen atom?

a zig-zag line

The bonds in molecules can be explained by valence-bond theory and hybrid orbitals, as well as by another model called molecular orbital theory.One reason why a molecular orbital differs from a hybrid orbital is because a molecular orbital...

applies to the the entire molecule.

Oxygen (O) is significantly more electronegative than carbon (C). Which is the least polar molecule (or most nonpolar molecule) that includes these two elements?

carbon dioxide (CO2)

Both carbon dioxide (CO2) and water (H2O) are molecular compounds made up of three atoms. Which has a linear shape, and why?

carbon dioxide only, because its central atom lacks any unbonded electron pairs

What makes up a triple bond?

one sigma bond (σ) and two pi (π) bonds

Compared to the H—C—H bond angle in methane, the H—N—H bond angle in ammonia is....

slightly smaller, due to the repulsion force of the unbonded pair of electrons.

The Lewis structure of propanamide is shown above. From left to right in this structure, what is the hybridization of the three carbon atoms and one nitrogen atom?

sp3, sp3, sp2, sp3

In every molecule that has a trigonal planar shape, such as the molecule of formaldehyde shown here, the three bond angles add up to 360 degrees. This means that the average bond angle in the molecule is 120 degrees. Which of the bond angles, if any, is the smallest?

the H—C—H angle

A chlorine atom has the electron configuration of [Ne]3s23p5. According to the valence-bond theory, the covalent bond in a molecule of chlorine (Cl2) forms from....

the overlap of two 3p orbitals, one from each chlorine atom.