Organic Chemistry And Carbon Bonding Flashcards
Why is Carbon so important?
Carbon has the ability to bind strongly to other elements and to form strong bonds to itself
Carbon is central to organic chemistry
What is the ground-state configuration of Carbon?
Putting electrons into its lowest state orbitals
C has 6 protons and hence 6 electrons and a mass of 12
How many unpaired electrons does Carbon have?
2 unpaired electrons
If carbon remained in ground state when forming covalent bonds, it would only form 3 bonds and only have 6 electrons in its outer shell
What is an example of covalent bonding in Carbon?
Methane
C
H
H
H
H
What is another example of covalent bonding in Carbon?
Ethane
C
H
H
H
Atomic Orbital Theory for Carbon
- S orbital can contain up to 2 electrons
- Each set of P orbitals can contains up to 6 electrons (3x2)
- Each set of D orbitals can contain up to 10 electrons (5x2)
- Each set of F orbitals can contain up to 14 electrons (7x2)
What is an In-Wave? M.O.T:
- constructive influence
- peaks and troughs are alligned
- produces region of highest probability of electron density
- wave produced with greater amplitude
What is an outer wave? M.O.T:
- destructive influence
- opposite shape to each other
- produces a wave with less/no amplitude
Dimensions of waves in orbitals:
- waves are three dimensional
- combine with in-phase waves producing regions with a higher probability of electron density and out-of-phase waves producing nodes, or regions of no electron density
What are bonding orbitals?
Electrons in a (os/in-phase) orbital are attracted by both nuclei at the same time and are more stable (of lower energy) than in isolated atoms. Adding electrons to these orbitals creates a force that holds the two nuclei together.
In phase orbitals produced:
OS
- lower energy molecular orbital
- electron density directly between the nuclei
- bonding orbitals
Out-of-phase orbitals produced:
O*S
- higher energy molecular orbital
- node between the nuclei’
- antibonding orbital
What is hybridisation?
Concept of mixing atomic orbitals form new hybrid orbitals suitable for the pairing of electrons to form chemical bonds in valence bond theory
Hybridisation of carbon process (sp^3) :
-promote a 2s electron into a 2p orbital, creating 4 orbitals of equal energy
- energy recovered from promotion by forming bonds
- carbon can now form 4 covalent bonds
-gives 8 electrons in outer shell = stable
Hybrid model is energetically favoured
What are organic molecules:
Organic molecules are usually composed of carbon atoms in rings or long chains, to which are attached other atoms of elements such as hydrogen, oxygen and nitrogen.
Organic molecules/ no. Of carbon atoms:
1-methane
2-ethane
3-propane
4-butane
5-pentane
6-hexane
7-heptane
8-octane
9-nonane
10-decane
11-undecane
12-Dodecane
What shape is an sp3 hybrid orbital?
- electrons in different orbitals repel each other
- if carbon forms 4 bonds to hydrogen atom, mutual repulsion will push the molecular orbitals as far apart as possible
- results in a tetrahedral arrangement, maximises distances of electrons in each of the bonds
Methane (CH4) tetrahedral, 109.5 bond angle
Ethane sp2 orbital:
- flat shape
- 120 bond angle
- sp2 orbitals form o-bonds by overlap with s-orbitals of hydrogen and sp2 orbitals of carbon
What is an o bond?
End-on overlap- more effective C-C o-bond
Stronger, less reactive
What is a pi bond?
Edgewise overlap- less effective
C=C pi-bond
Weaker; more reactive
Sp geometry:
4 atomic orbitals positioned as far apart as possible
- hybrid orbitals form the o-framework
- unhybbridsed p-orbitals give the pi-bonds
P/SP orbital bond angle- 90
SP/SP orbital bond angle- 180
Draw complex organic molecules (ethane):
sp3 hybridised: tetrahedral 109.5 degree bond angles
Draw complex organic molecule ethene:
Sp2 hybridised: trigonal 120 degree bond angles
Draw complex organic molecule ethyne:
Sp hybridised: linear 180 degree bond angles
