Atoms and bonding

Electronic configuration of carbon

What bond is formed first

sigma bonds

Hybridisation state of carbon with 4 single bonds

Angle between each sp3 orbital

How does Carbon bonds to H

SP3

Y

Hybridisation of carbon with a double bond

Shape and angle

sp2 -each atom in the bond must keep a p orbital free for the pi bond

The 3 sigma bonds are trigonal planar (same plane)

The Pi bond is in different plane

120 deg

Hybridisation of carbon ith a triple bond

SP = 2 pi bonds and one sigma bond1

Why are sp orbitals shorter

Less p character (50%)

sp2 has 60%

SP3 has 75%

= they are stronger bonds (3 bonds and atoms are closer to eacho ther) and more acidic due to a more stable conjugate base (negative charge on carbon is held in sp3 orbital)

Electronic configuration of N

How many bonds can N form?

3 covalent bonds, one lone pair left

Hybridisation state of N for single bonds

Why is NH3 isoelectric with methane

Lone pair in NH3 can make a sigma bond to H+ forming a molecule with the same electron configuration as methane

Hybridisation of N with double bond

SP2

Lone pai in SP2

Trigonal planar

Hybridisation of N in triple bond

sp

Lone pair in sp

Why is N a copycat

E.g. in an Imine HN=CR2

This also occurs when nitrogen is expected to be sp3 e.g. when bonded to an aromatic ring but it rehybridises into sp2 if the carbon that it is attached to is sp2 hybridised by being doube bonded to another atom in the ring.

Generally occurs whenever its attached to an sp2 carbon by a double or single or triple bond

Electronic configuration of O and what bodns can it form

Hybridisation of O when single bonds

sp3

104.5 due to repulsion

Hybridisation of O when double bonds

When does bond polarisation value increase

Greater electronegativity difference

Inductive effect

Shorter bonds = stronger dipole interaction

What is the effect of an electronegative group on a molecules pka

The positive charge can resonate = stability

Why does an amine and an amide have different pkas

Why do sp3 carbons have higher pkas

Why do imines have lower pka than amines

Why the pka of a nitrile so low

Why is pyridine a weaker base

Why is pyrrole a weaker base

Where are the lone pairs in this

How to increase stability of this with inductive effect of electron withdrawing groups

Pka is dependednt onn

resonance, inductive effect, hybridisation state

What moves in resonance

Lone pairs in p orbitals of sp2 hybridised atooms or the charge of a negatively charged atom (can even be a negatively charged carbon)

Lone pairs in p orbitals jump from p orbital to p orbital on the atoms

How to draw resonance structures

Double headed arrows

brackets

charges must b the same on both sides

How does resonance affect stability

If there is no difference between stability of 2 resonance structures

they exist in a 50:50 proportion in a mixture

Why do carboxylic acids have lower pka than alcohols

How to draw resonance when theres positive charge

Why is this more stable

Shape of benzene ring

Huckel's rules for aromaticity

Why are the 6 electrons in pi system in pyridine

Draw these compounds

Why is pyrrole aromatic

Where ar the electrons in these rings

Double bonded nitrogen - sp2 hybridised but it needs to use the p orbital for double bonds to C = can't use it to keep thr lone pair. So lone pair is in sp2

Draw resonance structures

Why are pentene ring anions aromatic

C1 starts off as sp3 and then loses h+, leaving behind a lone pair

Now it has only 3 bonds (C-C, C-C, C-H) and a lone pair. Need 3 sp2 orbitals for the bonds, the lone pair goes in p orbital so it can resonate and stabilise the structure

Why are pentene ring cations not aromatic

Why are N-containing 6 membered rings electron deficient

Is this structure electron deficient?

Why do resonance effects have more influence on electron density than inductuve effects

Why is phenol more reactive than benzene (aka poof that resonance always wins over inductive effects)