o chem exam 1

Bronsted-Lowry acid def Bronsted-Lowry base def with example

proton donor proton acceptor acid converts into conjugate base ex) HCl which is an acid converts into Cl- base converts into conjugate acid ex) NH3 which is a base converts into NH4+

DO HOMEWORK

questions 3, 5, 10

What can be used to explain the difference in acidity between acetic acid (CH3COOH) and ethanol (CH3CH2OH)?

resonance

resonance structures

resonance takes place in ions, electrons, and double or triple bonds have to be in conjunction/alternating a positive means is deficient in electrons, a negative means excess in electrons

covalent bond def

result from the sharing of electrons between two nuclei (usually nonmetal to nonmetal).

ionic bond def

result from the transfer of electrons from one element to another (metal and nonmetal).

Cation and anion def

cation: positively charged and has fewer electrons than protons anion: negatively charged and has more electrons than protons.

What is the formal charge of carbon in carbon monoxide (CO) when drawn with a triple bond?

-1

formal charge of CH3 (with one dot or electron on the C)

0

what is the pH of a .75 M acetic acid? Ka=1.8x10^-5

2.43 work is in notebook

unsaturation number formula

2C + 2 + N - H - X/2

What is the UN of C10H16ClNO2

3`

lewis acid vs base

Lewis acid is an electron pair acceptor A Lewis base is an electron pair donor.

practice drawing isomers for these: C4H10, C4H10O, C2H6O, C4H10O, C2H4O

slide 4 chap 2 has the answers

how to tell which direction of a reaction is more favorable

smaller the pka, the stronger the acid the reactions goes towards the weaker acid (higher pka) longer arrow for the more favorable direction, shorter arrow for the less favorable direction

resonance effect

the more delocalization of electrons the stronger the acid

Which of the following statements is true? a. the stronger the acid the smaller the pka b. the stronger the acid the smaller the ka c. the stronger the acid the bigger the pka d. the stronger the acid the further the equilibrium lies to the left

a

unsaturation number and structure

1 double bond takes 1 unsaturation # 1 cycle takes 1 unsaturation # 1 triple bond takes 2 UN #

a .100 solution of acetic acid has a hydrogen ion concentration of 1.32 x 10^-3 M. What is the acetic acid dissociation constant (Ka)?

1.77x10^-5 work is in notebook

What is the ground-state electronic configuration of a carbon atom?

1s2, 2s2, 2p2

How many constitutional isomers are there for C2H6O

2

How many constitutional isomers are there for C3H6

2

Which of the following statements about electronegativity and the periodic table is true? Electronegativity decreases across a row of the periodic table. Electronegativity increases down a column of the periodic table. Electronegativity increases across a row of the periodic table. Electronegativity does not change down a column of the periodic table.

Electronegativity increases across a row of the periodic table.

Conjugate base of CH3OH

CH3O-

What is the conjugate acid of CH3O- ?

CH3OH

Which of the following statements correctly describes the typical number of bonds for carbon, nitrogen,and oxygen in most neutral organic molecules? Carbon forms 4 covalent bonds, nitrogen forms 2 covalent bonds, and oxygen forms 3 covalent bonds. Carbon forms 4 covalent bonds, nitrogen forms 3 covalent bonds, and oxygen forms 2 covalent bonds. Carbon forms 4 covalent bonds, nitrogen forms 5 covalent bonds, and oxygen forms 2covalent bonds. Carbon forms 4 covalent bonds, nitrogen forms 5 covalent bonds, and oxygen forms 4covalent bonds.

Carbon forms 4 covalent bonds, nitrogen forms 3 covalent bonds, and oxygen forms 2 covalent bonds

what is an organic compound

Compounds having at least "C" & "H", "C" & "C" covalent bond Or Hydrocarbon with covalent bond

Which of the following is the weakest acid? HF, HI, HCl, HBr

HF bc of size of the atom

Which of the following molecules are constitutional isomers? I: CH3CH2CH2OH II: CH3CH(OH)CH3 III: CH3CH2OCH3 IV: CH3COCH3

I, II, III

Rank the following compounds in order of increasing acidity I: CH3COOH II: FCH2COOH III: ClCH2COOH IV: BrCH2COOH

I, IV, III, II

Which of the following molecules contain both covalent and ionic bonds? I: NaCl II: NH4OH III: CH3OH IV: MgCO3 I, II I, IV II, III II, IV

II, IV

Rank the following atoms in order of decreasing electronegativity, putting the most electronegative first. I: Si II: N III: O IV: C

III > II > IV > I

rank in increasing acidity I: CH3COOH II: ClCH2COOH III: CH3CH2OH IV: ClCH2CH2OH

III, IV, I, II

Arrange the following bonds in decreasing order of ionic character, putting the most ionic first. 1: C-C 2:C-N 3:C-O 4: Na-O I > II > III > IV IV > II > I > III IV > III > II > I IV > II > III > I

IV > III > II > I

What is the conjugate base of NH3 ?

NH2 -

Atomic number def

Number of proton in the nucleus, which is also equal to the number of electron

basic principles of resonance theory

Resonance structures are not real: only hybrid is real Resonance structures are not in equilibrium with each other: there is no movement of electrons from one form to another Resonance structures are not isomers

isomer def

Same molecular formula but different structural formula differ in both electrons and atoms

Which of the following statements about valence electrons is true? They are the most tightly held electrons. They do not participate in chemical reactions. They are the outermost electrons. They reveal the period number of a second-row element.

They are the outermost electrons.

determining bond angle/geometry

To determine the bond angel and shape first we have to count the number of groups surrounding the atom 2 groups linear 180 3 groups trigonal planar 120 4 groups tetrahedral 109.5

inductive effect ex

ability of electronegative atoms/ions to attract electrons towards itself because there are more electronegative elements the electronegative atom withdrawing electron density stabilizing the CB ex) structure with 3 Cl is going to be a stronger acid than a structure with 1 Cl ex) if all structures only have 1 Cl the closer to the negative charge is the strongest

acid vs base

acid: release of H+ ion in water base: release of OH- in water

size of atoms acidity (sizing effect) trends on periodic table

atoms become larger, pka decreases, acid gets stronger as you go down a group

Which of the following statements about resonance structures is true? a. resonance structures have the same placement of electrons but different placement of atoms b. resonance structures have the same placement of atoms but different placement of electrons c. resonance structures have the same placement of atoms and the same placement of electrons d. resonance structures have different placement of atoms and different placement of electrons

b

which of the following is the strongest acid? a. CH3NH2 b. BrCH2OH c. CH3OH d. CH3Cl

b because of the inductive effect

bond length trend on periodic table

bond length decreases across a row from left to right as the size of the atom decreases bond length increases down a group as size of atom increases

Which of the following statements about bronsted lowry acids and bases is true? a. gain of a proton by an acid forms its conjugate base b. loss of a proton from a base forms its conjugate acid c. loss of a proton from a acid forms its conjugate base d. bronsted lowry acid-base reactions always result in a transfer of a proton from a base to an acid

c

Which of the following statements about resonance structures is NOT true? a. There is no movement of electrons from 1 form to another b. Resonance structures are not isomers c. Resonance structures differ only in the arrangement of electrons d. Resonance structures are in equilibrium with each other

d

what changes and stays the same in resonance

electrons change, molecular formula same, arrangement of atoms same

Valence electron def

electrons in the outermost shell of orbitals, they determine the properties of an element, loosely held and participate in chemical reactions

exceptions to the octet rule

group 2 and 3 elements in third row can have up to 12 electrons around them

electronegativity effect

more electronegative more acidic

more resonance in the CB means

more stable = stronger acid.

formal charge equation

valence electrons-nonbonding electrons-number of bonds

solvation effect

you want the least amount of things covering up the hydrogen so water (solvent) can attract and stabilize the CB less things in the way more acidic