lecture 2 Flashcards

1
Q

what is orbital hybridisation

A

combining atomic orbitals to generate combinations of them

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2
Q

sp hybrid shape and angle

A

triple bond
linear
180*

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3
Q

sp2 hybrid shape and angle

A

double bond
trigonal planar
120

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4
Q

sp3 hybrid shape and angle

A

single bond
tetrahedral
109.5

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5
Q

if smt is in group 5,, how many bonds are needed for it to be sp3 hybridised

A

group 5 so 5 e-
needs 5 bonds in order to be sp3 hybridised

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6
Q

when do we see single connectivity

A

when we form discrete molecular systems
when we have units

which only contain a single free connecting unit.

aka a fg that will react with 1 other molecule.

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7
Q

example of single connectivity

A

lewis acid/base adducts
NMe3 + BPh3
N: attacking the B p orbital
——————————————————
condensation reaction between 2 moelcules only!! when both have OH groups,, and water is removed and theyre bonded through the ‘o’.

also called a condensation reaction as water is removed.

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8
Q

what is 2 connecting units

A

when the repeat unit has a connectivity of 2,,, the units can link in a consecutive way to form rings or 1D polymers

this is different to single connectivity as both sides of the molecule has a connective unit to it.

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9
Q

what do 2 connectivity units give rise to

A

either to rings or 1D polymers

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10
Q

1 connecting unit

A

the molecule only has 1 connecting point // connecting group

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11
Q

2 connecting units

A

when the molecules have 2 connecting pointssss // connecting groups and can form 1D polymers or ring systemssss

condensation reactions are a possibility

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12
Q

how do we draw a polymer

A

we draw the repeating unit with extended end lines,, with a bracket going through it and an ‘n’ at the bottom of the bracket.

-(- hello -)-

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13
Q

can u react a 1 connecting unit with a 2 connecting unit

A

yesss!!

we use this in order to cap polymers as a certain length // certain number of repeats

we can use the 1 connectivity at the ends as by connecting to the chain,, they have no more connecting sites.

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14
Q

polymers that have been capped can be called

A

discrete chains

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15
Q

how many bonds does a single connectivity unit make

A

1

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16
Q

how many bonds does a double conectivity unit make

A

it makes 2 bonds
which can either form a ring or 1D polymer

17
Q

what can units with 3 connectivities give ussss

A

planar sheets ✈️✈️✈️

or closed cagessss🦁🦁🦁

18
Q

what geometries can units with 3 connections haveee

A

can be trigonal planar //sp2

or tetrahedral with an unreactive site.

19
Q

final structure can be determined byyyyy

A

coordination geometries ( eg planar,, tetrahedral etccc)

20
Q

whats special about the 4 and 6 connectivity units

A

their geometries dictate their final lattice geometry

21
Q

4 / 6 connectivity units:
square planar connectivity units give whattt

22
Q

4/6 connectivity units:
tetrahedra connectivity givesss

A

3D network like graphite

23
Q

6 connections normally giveeeee

A

3D structures

24
Q

when building main group compounds what must we consider

A

energetics!!

the stability of the element form or the molecular forms

we normally look at 1D chains and rings

25
we must also consider
thermodynamics
26
what do we mean when we say thermodynamics
entropy and enthalpy
27
when is delta G favoured
when its negative when its smaller than 0
28
when is delta G not favoured
when its larger than 0.
29
equation for gibbs
delta G = delta H - T delta S
30
when we say covalent bonds,, what do we mean
sigma or pi bonds
31
iss CC or PbPb bonds stronger
CC is stronger bc it has a smaller atomic radius which means a greater degree of orbital overlap which means a stronger bond the bond is lower in energy
32
the more stable smt isss
the lower energy it hasss the lower enthalpy it hasss as it was storing less to begin with <3