5th - classical bonding

Question 1

octet rule

Answer 1

atoms react to get a full outer shell - most stable e- configuration.

usually main groups: ns2 np6

Question 2

what is the octet rule based on

Answer 2

empirical obervations
not rlly a rule
doesnt apply to all situations

Question 3

although bonds are usually called ionic and covalent, irl the bond is usually

Answer 3

between the 2
ionic character and covalent character

Question 4

what boding do organic solvents dissolve

Answer 4

covalent bonding

Question 5

ionic bonding structure

Answer 5

regular arrays of cations and anions

Question 6

what groups does ionic bonding occur between

Answer 6

1 18
2 17

Question 7

why does ionic bonding occur

Answer 7

the bonded element is usually more stable that the separate ions.

NaCl is more stable that Na+ Cl-

Question 8

what is ionic bonding based on

Answer 8

electrostatic forces of attraction between the positive and negative charged ions.

Question 9

why does ionic bonding not occur for d block elements

Answer 9

ionisation energy is too high to remove an electron.

in groups 1, ionisaion energy only increases for successive electrons

Question 10

where is covalent character seen in ionic bonding

Answer 10

when removing/ transferring more than 2 electrons.

this is due to the increased energy needed to remove it.

covalent character starts to occur

Question 11

ionic bonding occurs toooo

Answer 11

achieve the octet rule

Question 12

what is covalent bonding and when does it occur

Answer 12

in groups 13-16
when the IE energy is too high so ionic bonding isnt favoured.
when atoms share electrons in order to achieve the octet rule.

Question 13

theories in covalent bonding

Answer 13

lewis model: based on electrons as particles (electron pairs)
molecular orbital theory: based on electrons as waves (wave mechanics)

Question 14

lewis bonding model

Answer 14

chemical bonds consisting of a pair of electrons shared between the 2 atoms (to give a sigma bond)

Question 15

lewis bnding model double bond

Answer 15

2 pairs of electrons being shared between the atoms

Question 16

lewis bonding: if smt needs 5 electrons, how many electrons will it put out to share

Answer 16

5

number of bonds = number of valence electrons

Question 17

wha is the problem with lewis bonding model

Answer 17

aassumes that all valence electrons are equal however they aren’t.
we know p and s arent equal.

bonding = overlap of orbitals

electrons can be in s or p orbitals

Question 18

sp3 hydrid exp

Answer 18

valence electron is promoted to give 1 electron in each orbital
2s2 and 2p2 gives 2s1 2p3

these 4 are then averaged out to give 4 sp3 orbitals

Question 19

describe the 4 sp3 orbitals

Answer 19

same size
shape
directionallity
tetrahedral shape
109.5

Question 20

sp2 hybrids

Answer 20

mix of 2s and 2p orbitals
3sp2 hybrids = trigonal planar 120
unaffected 2p orbital overlaps with other 2p orbital side on to form a double bond

Question 21

sp hybrids

Answer 21

2 sp hybrid orbitals
2 unaffected 2p orbitals
overlap side on to give a triple bond (2 pi bonds)

Question 22

we can only average orbitals into hybrids when

Answer 22

the energy of the seperate orbitals are similar
3s 3p 3d are similar

2s 2p 3d arent similar PCl5 breaks octet rule

Question 23

if bonds are axial and ewuitorial these mean they arent

Answer 23

equal in energy

Question 24

how can 3rd period elements expand their octet rule

Answer 24

hbridise a dsp3 orbital
due to similar energy
still doesnt rlly work tho bc why is there only 1 d electron

this will also mean the bonds are equal in energy but in PCl5 they arent (2 axial and 3 equatorial)

Question 25

what are some of the p[roblems with lewis bonding

Answer 25

bond length changes in excited states (when molecules get excited)

o2 is said to have a full octet according to lewis structure however liquid o2 is blue, meaning it has unpaired electrons in the d orbital.

Question 26

polarised bonds are more

Answer 26

reactive than nonpolar ones.

Question 27

what causes a polarised bond

Answer 27

when a covalent bond occurs between atoms of different electronegativities.

e- will be closer to the more electronegative one.

Question 28

how can we show a bond is polarised

Answer 28

use the partially positive and negative signs

more electronegative has the partially - sign