The Names Bond (General)
What is the point of making a bond?
All chemical species want to reach the lowest possible energy state. A complete valence is very common “desired” final state for elements, which is accomplished by sharing or transferring electrons.
1. What is an ionic bond?
Ionic bonds are the electrostatic interaction between discrete fully positive and fully negative charges.
1. What is a covalent bond?
Covalent bonds are the sharing of electrons between two species.
Nonmetal-nonmetal
When drawing Lewis Structures, what are the two equations most important to know?
Hint: one for electrons, other for formal charge
S = N - A
The number of shared electrons is equal to the total electrons needed to fill the valence minus the electrons available (valence).
FC = Valence - (lone electrons + bonds)
~ FC = Valence - ("things it's touching")
What is the character of the bond in carbon monoxide?
Polar Covalent
What type of bond has the highest change in electronegativity?
Ionic Bond
Why do ionic bonds tend to form between metals and nonmetals?
Metals lose electrons because they have low ionization energies, while nonmetals gain electrons because they have high electron affinities. Also due to electronegativity differences.
1. What is the difference between a pure covalent bond and a polar covalent bond?
2. Give an example of a pure covalent bond and a polar covalent bond.
A pure covalent bond has 0 change in electronegativity.
Polar covalent bonds result from the electrostatic interaction between partial charges. Nonpolar covalent bonds result from equal sharing of electrons between two nuclei.
When drawing lewis structures, how do you account for:
1. a positive charge in a compound
2. a negative charge in a compound
(as seen in polyatomic ions)
account for positive charge by subtracting from AVAILABLE; account for negative charge by adding to AVAILABLE
How many lone pairs of electrons does the Oxygen atom have in the compound:
CH3CH2OH
2
What is the order of the following elements in increasing electronegativity?
O, N, F, H, C
H, C, N, O, F
Fill in the blank:
Metals (gain/lose) electrons to become (cations/anions) (positive charge)
Nonmetals (gain/lose) electrons to become (cations/anions) (negative charge)
Metals lose electrons to become cations (positive charge)
Nonmetals gain electrons to become anions (negative charge)
Fill in the correct words:
For covalent bonds, a (higher/lower) bond order gives a (longer/shorter) bond length, which indicates a stronger bond strength and thus indicates more stability.
For covalent bonds, a higher bond order gives a shorter bond length, which indicates a stronger bond strength and thus indicates more stability.
What does it mean for a compound to be in resonance?
Multiple acceptable Lewis Structures are available for a given compound, meaning that the compound actually exists as the average of all acceptable structures.
How many lone pairs of electrons are on the sulfur atom in sulfite ion, SO32-?
1
Which of the following has the weakest bond strength?
A. Hydrogen Bonds
B. Non-polar covalent
C. Polar Covalent
D. Ionic Bond
A
What does lattice energy indicate?
Lattice energy indicates the amount of energy necessary to overcome the negative potential energy binding the charges of an ionic compound.
dH = (q1q2)/r
When ranking lattice energies:
1. prioritize charge first; 2. if two ionic compounds have the same charge, the smaller one will have greater lattice energy; 3. Polyatomic ions are large.
What types of elements typically make a covalent bond?
nonmetal-nonmetal
List three rules that would constitute for an "acceptable" Lewis Structure?
Hints:
1. Where do you place negative charges (electronegative atoms vs. central atoms)
2. individual charges cannot exceed:
3. should you put charges on many or few atoms as possible
1. place negative charge only on electronegative atoms before central atom.
2. any individual charge cannot exceed +/- 1
3. put your charges on as few atoms as possible
What does it mean for electrons to be delocalized?
In the case of resonance, electrons are not confined to a single bond. Instead they "resonate" over multiple bonds. We call this delocalization.
What is the difference between an ionic bond and a covalent bond?
ionic bonds form between ions and involve the gain or loss of electrons. covalent bonds occur when electrons share between atoms.
Which has the greater lattice energy?
1. MgBr2 or CaCO3
2. MgO or CaSO4
CaCO3 (+2, -2)
MgO (SO4 is polyatomic so bigger)
What is the only type of bond that can freely rotate around the atoms on either side?
Single (sigma)
List three elements that do not follow the octet rule and explain why.
(H, He, Li, Be, B) or Period 3 and greater
Despite the fact that both C2H2 and HCN contain triple bonds, the lengths of these triple bonds are not equal. What do you think the best explanation is for this finding?
Bond length decrease as the bond order increases, and they also decrease with larger differences in electronegativity. (Think of that pull!)