Bonding and Forces - AP Chemistry

SF4 has 6 electron domains coming off of it- 4 F molecules and 2 lone pairs of e–. This is an example of see-saw shape.

COH2:

:O:

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H—C—H

This is a trigonal planar molecule, which only has bond angles of 120o

π bonds occur when there is greater than a single bond (double or triple bond). The only compound listed with double bonds or greater is CO2, meaning it is the one that contains the most π bonds.

Butane has 13 sigma bonds. Ethane has 7 sigma bonds. Benzene has 12 sigma bonds. Lithium Hydroxide has 2 sigma bonds and water has 2 sigma bonds.

when a central atom of a molecule has 6 electron domains coming off of it (none of which are lone pairs of electrons), it is considered octahedral

Each p subshell can have a maximum of 6 electrons in it. Note that there are three p orbitals, denoted px, py, and pz. These orbitals represent the plane in space in which they reside.

LiOH displays ion-dipole IMF, H2O displays hydrogen bonding, and CO2 displays dipole-dipole. Ion-dipole is greater than hydrogen bonding as an IMf, and hydrogen bonding is greater than dipole-dipole.

This is butanol. It is an alcohol; OH is the prime example of hydrogen bonding, which is the strongest intermolecular force.

Ionic bonds are the strongest type of bonds, followed by covalent bonds, hydrogen bonds, and lastly, van Der waals forces.

Ion-dipole forces are the strongest of the intermolecular forces.

Hydrogen bonding is a specific term for a particularly strong dipole-dipole interaction between a hydrogen atom and a very electronegative atom (oxygen, fluorine, or nitrogen). However, hydrogen bonds are still not as strong as ion-dipole interactions.

In order from strongest to weakest, the intermolecular forces given in the answer choices are: ion-dipole, hydrogen bonding, dipole-dipole, and Van der Waals forces.

Ionic bonding is stronger than any of the given intermolecular forces, but is itself NOT an intermolecular force. Ionic bonds are a permanent chemical connection between two atoms, whereas intermolecular forces as a more transient and temporary attraction between independent molecules.

Ionic and covalent bonds are not intermolecular forces;

Ion-dipole>hydrogen bonds>dipole-dipole>van Der Waals forces

IMF strength is in the order of ion-ion>h-bond>dipole-dipole>van der waals. Of the listed compounds there aren't any that display ion-ion IMF, and only ammonia has h-bonding, making it the one with the strongest forces.

Helium gas will have the lowest boiling point since it is a noble gas and the only intermolecular forces present are dispersion forces, which are the weakest. Acetone has a dipole, so dipole-dipole forces will be present. Water has a dipole and can also hydrogen bond, as can isobutyl alcohol. However, isobutyl alcohol is heavier than water, and will thus have the highest boiling point.

Ion-dipole forces are the forces responsible for the solvation of ionic compounds in aqueous solutions, and are the strongest of the intermolecular foces. Hydrogen bonding is the second strongest intermolecular force, followed by dipole-dipole interactions. London dispersion forces are present in all solutions, but are very small and the weakest of the intermolecular forces.

Noble gases are uncharged and do not have polar covalent bonds or dipole moments. The only force that could apply to them are dispersion forces.

A hydrogen bond is not a proper chemical bond, but the result of dipole-dipole interactions. While they are very chemically important, hydrogen bonds are dynamic, rather than stagnant. This is the least stable type of bond listed.

Covalent bonds are inherently more stable than ionic bonds as electrons are shared between both bound atoms, so the next stronges bond type is the ionic bond.

Chemists distinguish between covalent and ionic bonds for the sake of simplicity, but there is actually a continuum. Polar covalent bonds are on the continuum between pure ionic bonds and pure covalent bonds, so polar covalent bonds have more ionic character than nonpolar covalent bonds, and thus are less stable than nonpolar covalent bonds.

The choice "The slightly negatively charged sulfur atoms in are attracted to the slightly positively charged hydrogen atom of a nearby molecule" is exactly analogous to hydrogen bonding in water.

"Two methane molecules are attracted to one another because of temporary dipoles" describes London dispersion forces.

While "A negatively charged chlorine anion in solution will attract nearby positively charged Lithium cations" may sound like hydrogen bonding, it is more descriptive of interactions between any charged particles, not charged particles within the same molecule.

"Water completely dissolves certain salts, like " does not describe bonding at all.

While "The chlorine bound to carbon in dichloromethane will slightly attract positive charged particles" sounds promising, the slight charges are not on the same molecule.

Methanol is not an ionic molecule and will not exhibit intermolecular ionic bonding.

Methanol is polar, and will exhibit dipole interactions. It also contains the -OH alcohol group which will allow for hydrogen bonding.

Although the two molecules seem similar in structure, proponol has a higher boiling point due to the hydrogen bonding allowed by its alcohol group. This creates a strong intermolecular force, and extra energy is subsequently needed to break these bonds, resulting in a higher boiling point.

System pressure and temperature are related to boiling point, but are not necessary when comparing the properties of two molecules.

Dipole-ion interactions (an attraction between an ion and a neutral, but polar atom) are the strongest intermolecular forces listed. Ion-ion forces (attraction between two ions) are the strongest interactions overall.

Hydrogen bonding, an attraction between a hydrogen atom and a highly electronegative atom like fluorine, oxygen, or nitrogen, is the second strongest interaction listed.

The third strongest listed is dipole-dipole interactions, an attraction between two polar molecules, followed by dispersion forces, temporary shifts in the electrons of a molecule.