Chapter 8 and 9.1- Bonding

Question 1

3 different terms effectively meaning the same thing…
Define:
1. Dipole
2. Dipole Moment
3. Polar Bond

Answer 1

1. Something with 2 poles
2. A polar molecule (has a positive end and a negative end)
3. Polar bond (bond with unequal electron sharing)

Question 2

Formal charge and which formal charges are best

Answer 2

Group number - (dots + lines)
Best structure = closest to formal charge of 0 on ALL ATOMS, and if tied best = most negative charge on the most electronegative element

Question 3

Lewis structures:
1. Which element makes up the center?
2. Where do hydrogens go in a compound?

Answer 3

1. Least electronegative ones, carbon if it is present
2. If the center has been filled, the most electronegative ions

Question 4

Free radical

Answer 4

element with an unpaired lone electron

Question 5

When determining shapes using VSEPR Theory single, double, and triple bonds all count as…

Answer 5

single bonds

Question 6

How are dipole moments drawn? (individual AND overall)

Answer 6

Overall: Arrows with perpendicular lines at the bottom pointing towards the negative end
INdividual: For EACH polar bond use that weird little squiggle guy for positive and negative parts

Question 7

Heat of reaction of bonds

Answer 7

Sum of bonds broken - sum of bonds formed (in kj/mol)

Question 8

Breaking bonds is always…
Forming bonds is always…
(exothermic/endothermic)

Answer 8

Breaking bonds is endothermic
Forming is exothermic

Question 9

Bond order

Answer 9

Number of lines/number of locations

Tells us if lines are single double or triple, and therefore the energy length and energy. Higher values mean more attraction and shorter lengths, whereas the opposite is true for lower values.

Question 10

When is a bond ionic?

Answer 10

metal-nonmetal OR polyatomic ions

Question 11

Lone electron pairs repel other domains (more/less) than atoms (VSEPR)

Answer 11

more

Question 12

What are the electronegativity differences for nonpolar, polar, and ionic bonds respectively? (ex. Fluorine is 1.9 units more electronegative than Oxygen)

Answer 12

Nonpolar: 0.3 or below
Polar: 0.3-1.7
Ionic: 1.7-3.3

Question 13

What are the most electronegative elements?

Answer 13

Cl, N, O, F (in increasing order)

Charge (almost) always creates a bigger difference than energy level

Question 14

Difference between ionic, covalent, and metallic bonds?

Answer 14

Ionic: metal-nonmetal, moreso “stealing” of electrons rather than sharing, held together via opposite charge creating electrostatic attraction

Covalent: nonmetal-nonmetal, sharing of electrons to create stability

Metallic: like an electron “soup,” electrons don’t stay with any particular atom, using the force of attraction between the delocalized electrons and cations to hold the bond together

Question 15

As covalent bond interatomic distance decreases energy (increases/decreases)

Answer 15

increases until a point of maximum stability and lowest energy

Pulling the atoms too close will result in the force of repulsion between nuclei to overcome interatomic electron-nucleus attraction

Question 16

What is the purpose of resonance structures?

Answer 16

• To provide stability by sharing the uneven formal charge between atoms
• The stability of a structure (closeness to 0 on everything) determines the time spent in the structure

Question 17

What are the exceptions to the octet rules?

Answer 17

• 3rd period and below NONMETALS can use the d orbitals and have up to 6 bonds
• Boron can have 3 bonds
• Beryllium can have 2 bonds
• Hydrogen can have 1 bond

Question 18

Define domain

Answer 18

area of an electron (lone pairs, single bonds, double bonds, and tripe bonds all count as one)

Question 19

Name the bonds that make up single, double, and triple bonds

Answer 19

single: sigma bond
Double: 1 sigma bond, 1 pi bond
triple: 1 sigma bond, 2 pi bonds

Question 20

Polar vs. nonpolar covalent bonds

Answer 20

Polar - Unequal sharing due to diff. electronegativity, creating separate geometric centers of average positive and negative charge
Nonpolar - Equal pull/electronegativity of molecules

Question 21

When asked about lattice energy, the related equation is…

Answer 21

Coulomb’s law (relating charge first, and if the same then distance to force of attraction/energy holding the lattice together) (multiply the absolute value of charges of the atoms (do not take into account the # of atoms))

Question 22

How might orbitals change as an atom goes from a free state to a component of a molecule?

Answer 22

Hybridization of orbitals due to shifting electrons to arrange them in the manner with the least energy when existing free vs. in a molecule

Question 23

What energy level is 2sp3 closest to? 2sp2? 2sp1?

Answer 23

2sp3 is closest to 2p, being 75% p character, with 2sp2 being 67% p character and 2sp being in the middle with 50% p and 50% s character

Question 24

Which orbitals are atomic? Which are molecular?

Answer 24

Standard orbitals are atomic whereas hybrid orbitals (ex. sp3) are molecular

Question 25

When do Lewis diagrams/atoms have a lone pair before a single electron in each valence orbital?

Answer 25

In the case of the carbon family hybridizing its electrons in sp3, promoting all electrons into equal degenerate orbitals

Question 26

Breaking bonds are (exothermic/endothermic)

Answer 26

endothermic

Question 27

In determining bond length for covalent vs. ionic bonds…

Answer 27

Covalent: Prioritize whether bonds are single, double, or triple, then radius
Ionic: Ionic “bond lengths” should be determined by charge then radius (charge overcomes distance)

Question 28

Define covalent networks

Answer 28

Covalent molecules in a network (think crystal lattice w/o the whole + or - charges)

Most often made by Carbon or Silicon due to ability to bond to 4 molecules

Question 29

Is C-H polar?

Answer 29

nO

Question 30

Can halogens form double bonds?

Answer 30

non

Question 31

What is a sigma bond? a pi bond?

Answer 31

• A sigma bond is a direct sharing of electrons via overlapping orbitals
• A pi bond is a pair of parallel p orbitals that do not overlap and are perpendicular to the sigma bonds (attraction above AND below a sigma is 1 pi bond)

Question 32

Formula for determining net bond energy

Answer 32

Sum of REACTANTS - sum of products

Question 33

Does electronegativity have an impact on bond length?

Answer 33

No