Class 2 Flashcards
When determining ideal structure what things should you look for?
- Atoms obey octet rule 2. Formal charge = overall charge 3. Smallest set of formal charges 4. Posiitve formal charges on less EN atoms 5. Negative formal charges on more EN atoms
When drawing a Lewis structure, what atom should be central?
The least electronegative atom or carbon if there is one.
Formal charge must always equal what?
The overall charge!
What orbital geometric configuration is sp?
Linear
What orbital geometric configuration is sp2?
Trigonal planar
What orbital geometric configuration is sp3?
Tetrahedral
How does orbital geometry differ from molecular geometry/shape?
Oribtal geometry is solely based on sp level. Shape considers lone pairs/bonds.
What are the possible molecular geometries for sp hybridized molecules?
There is none! Same as orbital geometry
What are the possible molecular geometries for sp2 hybridized molecules?
bent (one lone pair)
What are the possible molecular geometries for sp3 hybridized molecules?
trigonal pyramid or bent (two lone pairs)
_____ bonds = stronger bonds = ______ bond dissociation energies.
Shorter bonds = stronger bonds = higher BDE
Breaking bonds is always what kind of process?
ENDOTHERMIC!
What kind of elements typically form covalent bonds?
High electronegative atoms (e.g. nonmetals with nonmetals).
Describe covalent bonds
- Electrons are localized between the two atoms. 2. Inflexible, hard, rigid compounds 3. Act as insulators
What is the difference between a polar covalent bond and a nonpolar covalent bond?
Nonpolar covalent = difference in EN of 0 Polar covalent = difference in EN > 0 but only slightly. A huge difference would result in an ionic bond.
How do you calculate the molecular dipole?
Add up all the bond dipoles.
Do metals strongly or weakly attract their electrons?
Weakly (they have low electronegativities!)
Describe metallic bonds
- Electrons are delocalized between the two atoms 2. Soft compounds 3. Act as conductors
What is a coordinate covalent bond?
Lone pairs from a nucleophile/ligand “bond” with electron-deficient species. Electrons are localized If the nucleophile shares more than 2 electrons, it is considered a chelate.
How does a coordinate covalent complex act? What is an example of one?
It is transient interaction, easily broken Iron atom in the heme unit
What’s a weird thing about Boron?
It is cool with 3 bonds.
What part of the heme unit does oxygen interact with? how?
Coordinates (forms a coordinate complex) with the iron.
What forms ionic bonds?
Electrostatic interaction between atoms of opposite charge (anion and cation)
Are ionic bonds insulators or conductors? Why?
Insulators because electrons are localized, and thus are rigid.
The larger the ionic charge, the _________ the ionic dipole force
larger
What is another term for dispersion forces?
diploe-induced dipole forces
What are dispersion forces?
Collisions within the electron cloud cause temporary but small dipoles deforming the cloud. More electrons will create a stronger force (more polarizable). Think of it like throwing clay against a wall-> temporarily deforms and sticks to the wall.
What is the weakest intermolecular force
(London) dispersion forces
Hydrogen bonds are formed between molecules that are very very ________.
Polar!
What is required to form a hydrogen bond?
A donor (N-H, O-H, F-H) and an acceptor (O: N: F:)
What three things can increase entropy?
- increase number of particles 2. increase the volume it occupies 3. increase the temperature Rearrangement does NOT affect entropy
What is the unit of entropy?
Joules/mol Kelvin
What is the eqn for entropy?
change in entropy = moles x entropy of products - molez s entropy of reactants
What is the (delta)H for an endothermic reaction?
positive
What is the (delta)H for an exothermic reaction?
negative
What is the difference between endergoinc and endothermic?
EnderGonic refers to (delta)G EnotHermic refers to (delta)H
ATP dephosphorylation is an _________ process.
Endothermic! Breaking bonds! BUT at high temps, it is EXERGONIC!! (and thus spontaneous)!
