Ch. 3: Bonding

Question 1

2 types of chemical bonds

Answer 1

Ionic: electrons are transferred from one atom to another and the resulting ions are held together by electrostatic interactions
Covalent: electrons are shared between atoms (orgo is deeply rooted here)

Question 2

Quantum Numbers

Answer 2

Describe size, shape, orientation and number of atomic orbitals an element possesses

Question 3

Principal Quantum Number

Answer 3

n, describes the energy level (shell) in which an electron resides and indicates the distance from the nucleus to the electron. Possible values range from 1 to infinity (mcat only tests up to 7). Smaller the number the closer the shell is to the nucleus and the lower its energy

Question 4

Azimuthal Quantum Number

Answer 4

l, determines the subshell in which an elecron resides. Possible values range from 0 to n-1. The subshell is oftn indicated w a letter: l=0 corresponds to s, 1 is p, 2 is d, 3 is f. Energy increases as number increases

Question 5

Magnetic Quantum Number

Answer 5

ml, determines the orbital in which an electron resides, its possible values range from -l to +l. Diff orbitals have diff shapes: s orbitals are spherical, p orbitals are dumbell shaped and located on the x-, y-, or z- axis

Question 6

Spin Quantum Number

Answer 6

ms, describes the spin of an electron, possible values are +/- ½

Question 7

Molecular Orbitals

Answer 7

Form when 2 atomic orbitals combine, obtained mathematically by adding or subtracting the wave functions of atomic orbitals

Question 8

Node

Answer 8

Location in an orbital where probability of finding electron is 0

Question 9

Bonding Orbitals

Answer 9

Created by head to head or tail to tail overlap of atomic orbitals of the same sign and are energetically favorable

Question 10

Antibonding Orbitals

Answer 10

Created by head to head or tail to tail overlap of atomic orbitals that have opposite signs and are energetically unfavorable

Question 11

Single bonds

Answer 11

Are sigma bonds which contain 2 electrons

Question 12

Double bonds

Answer 12

Contain one sigma bond and one pi bond. Pi bonds are created by sharing of electrons between 2 unhybridized p-orbitals that align side-by-side

Question 13

Triple bonds

Answer 13

Contain one sigma bond and 2 pi bonds

Question 14

Flexibility and strength

Answer 14

Multiple bonds are less flexible than single bonds bc rotation is not permitted in the presence of a pi bond. Multiple bonds are shorter and stronger than single bond, although individual pi bonds are weaker than sigma bonds

Question 15

Hybridization

Answer 15

Hybrid orbitals are formed by mixing diff types of orbitals

Question 16

sp3 hybridized orbitals

Answer 16

25% s character and 75% p character. Form tetrahedreal geometry w 109.5* bond angles carbons w all single bonds are sp3 hybridized

Question 17

sp2 hybridized orbitals

Answer 17

Have 33% s character and 67% p character. Form trigonal planar geometry w 120* bond angles. Carbonds w one double bond are sp2 hybridized

Question 18

sp hybridized orbitals

Answer 18

Have 50 % s character and 50% p character. Form linear geometry w 180* bond angles. Carbonds w a triple bond, or with two double bonds are sp hybridized

Question 19

Resonance

Answer 19

Describes delocalization of electrons in molecules that have conjugated bonds, increases stabliltity of a molecule, various resonance forms al contribute to the true electron density of the molecule; the more stable the resonance form, the more it contributes. Resonance forms are favored if they lack formal charge, form full octets on electronegative atoms or stabilize charges through induction and aromaticity

Question 20

Conjugation

Answer 20

Occurs when single and multiple bonds alternate, creating a system of unhybridized p-orbitals down the backbone of the molecule through which pi electrons can delocalize