CHM 255 Exam 1 Word Scramble
|
Embed Code - If you would like this activity on your web page, copy the script below and paste it into your web page.
Normal Size Small Size show me how
Normal Size Small Size show me how
Question | Answer |
Each electron shell contains ______ electrons. | 2n^2 |
What are the 3 rules for filling orbitals | 1. Fill lower electron energy orbitals 1st 2. No more than 2 electrons/ orbital 3. Fill all orbitals with same energy with 1 electron before putting into 2nd |
Describe the shapes of s and p orbitals | S-orbital: spherical P-orbital: 2 lobes |
Define electronegativity | how tightly an atom holds on to its electrons |
What is the most electronegative atom and it's value | Flourine; 4.0 |
Electronegativity trend | Increase right and up |
Differentiate between ionic and covalent bonding | Ionic: electron transfer; eneg. diff. > 1.9 (large) Covalent: electron share; eneg. diff. <1.9 (>0.5 = nonpolar) |
How can you tell if an atom has a partial negative or positive charge? | The more electronegative atom has a partial negative |
Know electron configuration; lewis structure | |
Formal charge formula | (Initial # valence electron) - (# nonbonded electron) - (1/2)(# bonded electron) |
* FORMAL CHARGE CHART * | |
Define alkane, alkene, and alkyne | Alkane: single CH bonded chain Alkene: CH chain with double bond(s) Alkyne: CH chain with triple bond(s) |
Alcohol | OH (hydroxl) group |
Ether | single bonded C-O-C |
Amine | Single bonded N-H on chain |
Aldehyde vs. Ketone | Aldehyde: R-C=O(-H off C also) at the END Ketone: R-C=O(R' off C also) in the middle |
Carboxylic acid | R-C=O(-OH on C also) |
Ester | R'-C(=O)-O-R |
Amide | R"-C(=O)-N-R(R') |
Phosphate Ester | Central P with =O, 2 O-, and O-R bonded at four sides Holds DNA together |
What are bond angles and the shape of molecules dictated by? | A desire to keep the valence shell electrons as far away from one another as possible |
Tetrahedron | 4 atoms or electron pairs bond angle 109.5 |
How do unpaired electrons affect bond angles | Lead to greater repulsion and change angles |
Trigonal Planar | 3 atoms or electron pairs bond angle 120 |
Linear arrangement | 2 atoms or electron pairs bond angle 180 |
An atomic orbital determines _____ % probability to find and electron there | 90 |
Two 1s orbitals form a _____ bond Two 2p orbitals form a _____ bond | Sigma; Pi |
Hybridization of atomic orbitals | Number of electron dense areas... 4=sp3 3=sp2 2=sp |
How many sigma & pi bonds? a. sp3 b. sp2 c. sp | a. 4 sp3 --> 4 sigma b. 3 sp2 + 1 p ---> 3 sigma; 1 pi c. 2 sp + 2 p ---> 2 sigma; 2 pi |
Which are hybridized, atoms or bonds? | Atoms |
Describe resonance | The real structure of a molecule (resonance hybrid) is a composite of contributing structures |
In arrow pushing, where does the arrow start? | The site of the electrons you want to move |
Preference in resonance structures given by what 4 things? | 1. Atoms with completed octets 2. Maximum # covalent bonds 3. Least separation of unlike charges 4. Negative charge on more electronegative atom |
Electronegativity: C, H, N, O, F, Cl, Br | C: 2.5; H: 2.1; N: 3.0; O: 3.5; F: 4.0; Cl: 3.0; Br: 2.8 |
Prefixes for 1-10 Carbons | 1-meth; 2-eth; 3-prop; 4-but; 5-pent; 6-hex; 7-hept; 8-oct; 9-non; 10-dec |
Infixes for IUPAC naming | Indicates nature of C-C bonds an- all single bonds en- double bond(s) yn- triple bond(s) |
Suffix for each functional group in IUPAC (hydrocarbon, alcohol, aldehyde, ketone, carboxylic acid) | e-hydrocarbon; ol-alcohol; al-aldehyde; one-ketone; oic acid-carboxylic acid |
Intermolecular forces of attraction are known as ____________: caused by temporarily induced dipole moments in atoms and molecules | dispersion forces |
What causes boiling point to increase? | The number of atoms and most branching |
What creates a temporary electron dipole? | Unsymmetrical electron density |
The boiling point of a compound is ___________. ________ is needed to overcome attractive forces that occur in the liquid state. | The temperature at which liquid molecules are converted into gas; Energy |
Define conformation | any 3_d arrangement of atoms that results from rotation around single bonds |
The conformations that we care about are the ___________ (least favorable) and ________ (most favorable) | highest energy; lowest energy |
To draw a _____________ look down the C-C bond and flatten | Newman Projection |
In the _________ conformation H's are as far apart as possible In the _________ conformation H's are on top of each other | staggered; eclipsed |
Which has the highest energy, eclipsed or staggered conformation? | eclipsed |
Eclipsed conformation has ________ _______. | Torsional strain |
What are the different types of staggered conformation and their relative energies | Lowest energy has CH3 groups farthest apart: "anti" Other ways to arrange staggerd are ~0.9kcal/mol higher in energy: "gauche" |
What are the different types of eclipsed conformation and their relative energies | 2 conformations with CH3 groups not as close as possible ~ 3.5 kcal/mol higher than "anti" Highest energy structure has both CH3 groups eclipsed and is ~5kcal/mol higher energy than "anti" |
What are constitutional isomers | molecules with the same molecular formula but a different arrangement of atoms |
* Review substituent chains * (esp. iso, sec, tert) | |
What do you do when there are two or more of the same substituents | 1. Number where the substituents are on the chain 2. Use prefix before substituent name (i.e. di, tri, etc.) |
When both substituents are in equivalent positions, the one with _____________ gets the lowest number | the lower alphabetical ordet |
Do you use prefixes when alphabetizing? | ONLY iso and neo |
For cycloalkanes with one substituent... | don't use a number in naming, simply methylcyclo() |
How do you number cycloalkanes with 2 or more substituents | Number the ring starting with the substituent with the lowest alphabetical order |
Why are the hydrogens in O-H more acidic than the hydrogens in C-H3 in acetic acid? | Acidity increases with electronegativity! |
How can you determine which direction an equilibrium of an acid base reaction wil lie? | Lies towards higher pKa |
What's the trick for determining if you've numbered correctly in a multiple choice? | Want the number of substituents to add to the lowest possible number (i.e, 4,5,5 > 3,4,4) |
What do we know about cyclopropane in terms of strain, shapes, and angles? | Carbons are planar with 60 deg. angles' lots of angle and torsional strain |
Eclipsed CH's lead to ___________ strain; An angle less than _____ leads to angle strain. | torsional; 109.5 |
What do we know about cyclobutane in terms of strain, shapes, and angles? | Butterfly shaped; 88 deg. angles; angle strain |
What do we know about cyclopentane in terms of strain, shapes, and angles? | Envelope shaped; 105 deg. angles |
What do we know about cyclohexane in terms of strain, shapes, and angles? | Most stable conformation is the CHAIR shape |
What's the difference between axial and equatorial? | Ax: up and down on alternating carbons Eq: slanted on angles in the opposite direction of the axials |
If all CH's are _____________ there is NO torsional strain | staggered |
What's the highest energy conformation for a cyclohexane & 3 characteristics? | Boat (both ends point in same direction) Steric clashing; torsional strain; 6.5 kcal/mol higher energy than chair |
What is the twist boat conformation? | A twists of the boat to relieve strain and sterics that i s1kcal/mol lower in energy than the boat conformation |
What is steric clashing? | When -H H- are facing towards one another |
Why are equitorial substituents prefered over axial | Axial provide steric interaction; Equitorial is 1.7 kcal/mol more stable |
The __________ the substituent the worse the interactions | larger |
What's the equation to determine free energy difference betqeen equitorial and axial substituents? | (Delta G) = -2.3 R T log(Keq) |
When there are two substituents they can be on the same side (______) or opposite sides (________). | cis; trans |
Which is the highest and lowest energy chair conformation - cis or trans? | Trans with axial = highest; trans with equitorial = lowest |
When attempting to obtain the lowest energy conformation always put the larger group in ___________(axial/equatorial). | equitorial |
Define delocalization | Spreading electron density over a large surface area |
How do you determine which resonance structure would contribute the most to the hybrid (3) | WANT: 1. More covalent bonds 2. Least # lone pairs 3. Saturated carbons |
Bronsted-Lowry acid | Proton donor |
Bronsted-Lowry base | Proton acceptor |
Bronsted-Lowry conjugate acid | Base accepts a proton (+) |
Bronsted-Lowry conjugate base | Acid loses a proton (-) |
Difference between week and strong acid/base | Strong completely donates/accepts H+; weak doesn't completely |
How do we measure the strength of an acid? | pKa |
When deciding if one acid is more acidic than the other you should...? | compare the stability of the conjugate bases |
What determines conjugate base stabilization (4) | 1. Inductive effect 2. Resonance 3. Electronegativity of the atom with the anion (across) 4. Hybridization of the atom the anion resides on 5. Bond dissociation energy (down) |
What is the inductive effect | When there is a nearby group that can pull electronegatively away from the central atom |
As electronegativity increases, what happens to the stability of the conjugate base and why | Stabilized because it can better accommodate the negative charge |
How does acidity change with bond energy down the periodic table and why? | Lower BDE = more acidic because of the overlab of the orbitals |
How does hybridization affect conjugate base stability | sp lower in energy than sp2 or sp3... so more acidic |
Created by:
jkmccord11
Popular Chemistry sets