chem bonding - lecture 1

Question 1

what does the octet rule state

Answer 1

atoms bond together to achieve a stable electron configuration, aka a full outer shell

Question 2

what does a full outer shell mean

Answer 2

ns2 np6 = 8 total electrons for the octet rule
noble gas configuration

Question 3

whats wrong with the octet rule

Answer 3

its more of an empirical observation
its not a rule
it doesnt always apply
gives no exp into why ns2 np6 is most stable

Question 4

ionic bonding

Answer 4

electrostatic forces of attraction

Question 5

what atoms is ionic bonding common for

Answer 5

elements that need to gain/lose 1-2 electrons to reach octet configuration

Question 6

why doesnt ionic bonding work for all elements

Answer 6

moving more than 2 electrons will start to require more and more energy as u are removing - electrons from a + nucleus

moving more than 2 electrons will require way too much energy + covalent character will start to occur.

Question 7

what is organic solvent used to dissolve

Answer 7

covalent bonds

Question 8

when does covalent bonding occur

Answer 8

when ionisation energy becomes too high, atoms start to share electrons to make the octet rule

Question 9

the two covalent bonding theories are

Answer 9

lewis model
molecular orbital theory

Question 10

what is the lewis model based on

Answer 10

based upon electron pairs
based on particles
used mainly in organic chem

Question 11

what is the molecular orbital theory based on

Answer 11

based upon wave mechanics
equation based

Question 12

lewis model explanation

Answer 12

chemicals bonds consisting of a pair of electrons being shared between two atoms.
both atoms see the shared electrons and the fact it has a full outer shell (effective electronic configuration)
the shared pair of electrons form a sigma bond

Question 13

N has 5 electrons but needs 3 more to have a full outer shell, how many electrons will it put out to share

Answer 13

3

Question 14

what is a problem with the lewis bond

Answer 14

assumes that all valence electrons are equal
but electrons can be from different orbitals (s,p,d etc)

Question 15

sp3 hybrids have what in common

Answer 15

size
shape
directionality

Question 16

what shape do the sp3 hybrids have

Answer 16

tetrahedral shape

Question 17

what molecule goes against the octet rule

Answer 17

PCl5
10 Cl molecules around the P

Question 18

if n=3, what orbitals can we use in hybrids

Answer 18

s
p
d
as theyre all similar in energy
theyre all valence orbitals aka there are outer electrons in those orbitals

Question 19

when n=2, what orbitals can u use in hybrids

Answer 19

s
p
as those are the valence orbitals
d orbitals are too high in energy and therefore inaccessible as electrons are not in the d orbitals.
we cannot access the d orbitals unless u put in energy (excitation?)

Question 20

what period can expand their octet rule

Answer 20

3rd period

Question 21

what periods cant
expand their octet rule

Answer 21

1st
2nd

Question 22

wait so why doesnt the dsp3 hybrid not explain bonding in PCl5

Answer 22

dsp3hybrids state that all bonds will be the same length as they are the averge of 1d, 1s and 3p orbitals
however
the bonds in PCl5 are not equal!!
theres 3 on the equitorial axis and 3 on the axial axis