Molecular Bonding & Hybridization

Electronegativities of Atomic Orbitals...

s > p - s-orbital is more electronegative than p-orbital because of its more regular and stable shape

Electrostatic Potential Maps

shows electron poor and electron rich regions

Pi Bond

sideways overlap of unhybridized p-orbitals (weaker yet non-rotational bond) always perpendicular to sigma bonds

Hybridization & Electronegativity

sp > sp2 > sp3 - because hybridized orbitals become increasingly similar to s-orbitals thus are more electronegative

Tetrahedral Carbon

sp3 hybridized carbon atom bearing for substituents directed at 109.5 from each other, with solid lines representing bonds on the plane of the page

Excited State

state in which a molecule has a higher potential energy than it has in its ground state, molecule must be energized for unfavorable moving of electron to a higher energy state - much more reactive

The more alike a hybridized p-orbital is to an s-orbital...

the more electronegative the orbital - why sp orbitals are more electronegative than sp2 and sp3 (largest circular shape)

Atoms bond together because...

the resulting compound that results is more stable and lower in energy than the separate atoms

sp2 Hybrid Orbitals

the s-orbital is only hybridized with two p-orbitals leaving one unhybridized p-orbital

The greater the energy difference between atoms...

the weaker the bond will be if it were to form

The greater the starting energy difference between two atoms...

the weaker their bond will be, C-F > C-I

Molecular Orbital Formation

they are in lower energy than the original unbonded atoms to allow the reaction to be favorable

sp3 Hybrid Orbitals

unsymmetrical about the nucleus (to allow overlapping of orbitals and stronger bonds), tetrahedral

Lone Pair Electrons

valence electrons that are not utilized for bonding (technically) - still effect the bond

sp Hybrid Orbitals

~ linear, the s-orbital is only hybridized with one p-orbital leaving two unhybridized p-orbitals

Molecule

(MO) neutral group of atoms held together by covalent bonds

Valence Bond Theory

a covalent bond forms when two atoms approach each other closely and a singly occupied orbital on one atom overlaps a singly occupied orbital on another atom

Electronegativity

ability of an atom to hold onto and attract the shared electrons in a covalent bond

Bond Strength

amount of energy required to break the bond between atoms

Negative charges on carbon atoms...

an sp carbon will sustain a negative charge more than an sp3 carbon because it is more electronegative

Positive charges on carbon atoms...

an sp3 carbon will sustain a positive charge more than an sp carbon because it is less electronegative

Bond Angle

angle formed between bonded atoms, specific geometry and property

Polar Covalent Bond

bonded electrons are attracted more strongly by one atom than the other making electron distribution unsymmetrical

p-orbitals...

can't hold onto electrons like s-orbitals can - uneven, irregular shape

Valence Electrons...

determine how many bonds an atom can form

Sigma vs Pi Bond

direct overlap vs sideways overlap, overlap of unhybridized p-orbitals in pi bonds provide less surface area than direct overlap of sigma bonds

When a bond forms...

energy is released and flows out of the system (the product is less energetic than the two reactants, so energy is released)

When a bond breaks...

energy is required and flows into the system (the products are more energetic than the reactant, so energy is required to break-up that favorable arrangement)

Hybridization

explanation of why all 4 bonds between carbon and hydrogen are the same, hybrid orbitals are a combination between s and p orbitals to make them the same energy level

Sigma Bond

head-on-head overlap of hybridized s and p orbitals (much stronger interaction)

HOMO

highest occupied molecular orbital

Covalent Bond Explanation

it would require too much energy for an atom to either gain or lost electrons, so instead they share electrons to achieve the noble-gas configuration

Favorable Formation of Hybrid Orbitals...

lower more electrons than raising electrons to that middle hybridized orbitals (easier to move electrons to lower energy state than higher energy state)

LUMO

lowest unoccupied molecular orbital (doesn't exist in excited state)

Non-Bonding vs Anti-Bonding

non-bonding valence electrons do not directly interact but they still form hybrid orbitals, anti-bonding molecular orbitals are unfavorable high-energy orbitals that express disruptions in the molecule

Bond Length

optimum distance between nuclei that leads to maximum stability of a molecule

Valence Shell

outermost energy shell of an atom, containing the valence electrons involved in the chemical reactions of that atom ~ determine the behavior and reactivity of atom

Single Bond

overlap of two hybridized orbitals (one sigma bond)

Double Bond

overlap of two hybridized orbitals and one pair of unhybridized p-orbitals (one sigma and one pi bond)

Triple Bond

overlap of two hybridized orbitals and two pairs of unhybridized p-orbitals (one sigma and two pi bonds)

Non-Bonding Electrons

pairs of electrons that undergo hybridization but their valencies are already filled and do not participate in the reaction

Unhybridized p-orbitals are...

perpendicular to the plane hybridized orbitals and also perpendicular to other unhybridized p-orbitals

Molecular Orbitals

region in a molecule where atomic orbitals overlap, resulting in either a stable low-energy bonding orbital or an unstable high-energy antibonding orbital ~ electrons no longer belong to atomic orbitals