Organic Chem: Intro Flashcards
(36 cards)
Which group of the periodic table is carbon in?
14
How many valence electrons does carbon have?
4
What is carbon’s electron configuration?
1s^2 2s^2 2p^2
What is carbon’s valence shell configuration?
2s^2 2p^2
What is carbon’s electronegativity?
2.5
What is electronegativity?
How much an atom attracts a bonding pair of electrons
What bond type is expected for carbon?
Covalent: between atoms with equal electronegativity
Polar covalent: between atoms with differing electronegativity
What is an empirical formula?
The simplest whole number ratio of elements
What is carbon’s empirical formula?
C3H7
What is a molecular formula?
The actual number of atoms of each element
What is carbon’s molecular formula?
C6H14
What is a structural formula?
Minimal detail for an unambiguous structure
What is a displayed formula?
Relative placing of atoms and bonds between them
What is a skeletal formula?
The carbon skeleton and functional groups only
What is a sigma bond?
End to end overlap bond
Orbitals overlap as two atoms approach
Electrons of one atom attracted to nucleus of the other
This continues until repulsion between nuclei outweighs this attraction
Describe the structure of methane.
Four C-H bonds of identical length and tetrahedral geometry
Bond angle: 109.5 degrees
How do we know s and p orbitals get mixed to form hybrid orbitals?
A carbon atom in ground state wouldn’t form four single bonds
Promoting a 2s electron into an empty 2p orbital gives 4 unpaired electrons
Methane would have 4 bonds in this case, but one would be a different length
However, all four bonds in methane are equal
So, the bonding atomic orbitals of carbon must be equivalent
s and p orbitals get mixed to form hybrid orbitals
What is sp^3 hybridisation?
One s and three p orbitals getting mixed
Describe sp^2 hybridisation.
One s and two p orbitals mix
Gives bond angle of 121.3 degrees
When carbon is only bonding to three atoms
The three hybrid orbitals can form three sigma bonds
What can form a pi bond in sp^2 hybridisation (e.g. ethene)?
The two pure p orbitals of the two carbon atoms can overlap sideways to form a pi bond
Describe the structure of benzene.
Planar molecule
Each carbon atom is sp^2 hybridised
6 electrons in pure p orbitals capable of overlapping
Get delocalisation over the ring
What is sp hybridisation?
Mixing one s orbital and one p orbital to obtain two sp hybrid orbitals
How many pure p orbitals are left over per carbon atom in sp hybridisation and what does this mean?
Two pure p orbitals are left over per C so two pi bonds are formed
Each carbon atom forms two sigma bonds and two pi bonds
What are some properties of organic compounds?
Physical and chemical behaviour of organic compounds are heavily influenced by the polarity of the molecule
Most organic compounds are not soluble with water
Organic compounds with oxygen and nitrogen atoms are somewhat soluble because the electronegative atoms form hydrogen bonds with water
Many organic compounds undergo combustion and burn vigorously in air
