Bonding and Chemical Interactions

Question 1

Name some of the elements that are exceptions to the octet rule.

Answer 1

1. Hydrogen
2. Helium
3. Lithium (stable with 2 e-)
4. Beryllium (stable with 4 e-)
5. Boron (stable with 6 e-)
6. All elements in period 3 or greater, which can expand the valence shell to include more than 8 electrons by incorporating d-orbitals)

Question 2

If the electron pair in a covalent bond is shared equally, the bond is _____.

Answer 2

Nonpolar (covalent)

Question 3

If the electron pair in a covalent bond is shared unequally, it is ______.

Answer 3

Polar (covalent)

Question 4

If both of the shared electrons are contributed by only one of the two atoms, the bond is called _______ covalent.

Answer 4

Coordinate

Question 5

List some characteristics of ionic compounds.

Answer 5

1. Very high melting and boiling points
2. Dissolve readily in water and other polar solvents
3. Good conductors of electricity in the aqueous state
4. In the solid state, form a crystalline lattice

Question 6

The number of shared electron pairs between two atoms is called the bond ____.

Answer 6

Order

Question 7

How do the bond lengths compare in single, double, and triple bonds?

Answer 7

From longest to shortest: single > double > triple

Question 8

How does the bond energy differ in single, double, and triple bonds?

Answer 8

From greatest energy to least energy: triple > double > single

Question 9

What are the seven common diatomic molecules?

Answer 9

Hydrogen, nitrogen, oxygen, fluorine, chlorine, bromine, and iodine

Question 10

Any bond between atoms with a difference in electronegativity less than ____ is generally considered nonpolar.

Answer 10

0.5

Question 11

The electronegativity difference in polar covalent bonds ranges from ____ to ____.

Answer 11

0.5 to 1.7

Question 12

The dipole moment of a polar bond or polar molecule is a vector quantity given by the equation p = __ __.

Answer 12

p = qd, where p is the dipole moment, q is the magnitude of the charge, and d is the displacement vector separating the two partial charges.

Question 13

Does a Lewis acid accept or donate a pair of electrons?

Answer 13

Accepts

Question 14

If Lewis structures show the same bond connectivity and differ only in the arrangement of the electron pairs, these structures represent different ____ forms of a single compound.

Answer 14

Resonance

Question 15

True or false: The Lewis structure that minimizes the number and magnitude of formal charges is usually the most stable arrangement of the compound.

Answer 15

True

Question 16

True or false: When drawing out the backbone of a compound in a Lewis dot structure, the least electronegative atom is the central atom.

Answer 16

True

Question 17

What elements typically occupy a terminal position in a Lewis dot structure?

Answer 17

Hydrogen and the halogens F, Cl, Br, and I (usually)

Question 18

The difference between the number of electrons assigned to an atom in a Lewis structure and the number of electrons normally found in that atom’s valence shell is the ____ ____.

Answer 18

Formal charge

Question 19

Give an equation used to determine formal charge.

Answer 19

formal charge = V - # of nonbonding electrons - number of bonds
(where V is the number of valence electrons in the neutral atom)

Question 20

True or false: In general, the more stable the Lewis structure, the more it contributes to the character of the resonance hybrid.

Answer 20

True

Question 21

One can use formal charge to assess the stability of resonance structures according to the following guidelines: (Study Card)

Answer 21

1. A Lewis structure with small or no formal charges is preferred over a Lewis structure with large formal charges.
2. A Lewis structure with less separation between opposite charges is preferred over a Lewis structure with a large separation of opposite charges.
3. A Lewis structure in which negative charges are placed on more electronegative atoms is more stable than one in which the negative formal charges are placed on less electronegative atoms.

Question 22

Electronic geometry describes the spatial arrangement of what?

Answer 22

It describes the spatial arrangement of ALL pairs of electrons around the central atom, including both the bonding and the lone pairs.

Question 23

Does molecular geometry describe the spatial arrangement of bonding or nonbonding pairs around the central atom?

Answer 23

Bonding

Question 24

The _____ number is the number of of atoms that surround and are bonded to a central atom.

Answer 24

Coordination

Question 25

True or false: the presence of bond dipoles will result in a molecular dipole.

Answer 25

False. A compound with polar bonds may be polar or nonpolar, depending upon the spatial arrangement of the polar bonds in the molecule.

Question 26

Rank the common intermolecular forces in order from strongest to weakest.

Answer 26

1. Hydrogen bonding
2. Dipole-dipole interactions
3. Dispersion forces (aka London forces or van der Waals forces)

Question 27

Which electronegative elements are capable of forming hydrogen bonds?

Answer 27

Nitrogen, oxygen, and fluorine