Chapter 1 Pre-read

Before class

Organic Chemistry

the chemistry of compounds that contain the element carbon

Why is carbon the basis of organic chemistry

they are the central to the structure of living organisms and therefore to the existence of life on Earth. 

Why did nature choose carbon to create life?

Because carbon can easily bond with itself to make carbon chains and can easily bond with other elements like Hydrogen, nitrogen, oxygen and sulfur

Compounds

made up of elements

Elements

made up of atoms

Atoms

made up of a nucleus that has protons and neutrons surrounded by electrons

Atomic number

number of protons, equal to the number of electrons

Isotope

atoms of the same element that have different masses. Ex. C-12 and C-6

How are isotopes made:

they are made because an element can vary in the number of neutrons it carries

Shells

electrons that surround the nucleus

Valence shell

outermost shell where chemical bonds are made

How do we know how many valence electrons an atom has?

The number of electrons is equal to the group number

Ionic bonds:

formed through transfer of electrons

Covalent bonds

formed through sharing electrons

Ions

charged molecules

Salts

ionic compounds that are formed from very different electronegativities

How are noble gasses made

when electrons of the same or similar electronegativities bond to make a covalent bond

Carbon carbon single bond

2 carbon atoms use one electron pair to bond

Dashed wedges

behind the plane of paper

Solid wedges:

in front of paper

How do you find a formal charge?

For each element you take valence electrons - (½)shared electrons- unshared electrons

Are most non-metal non-metal bonds ionic or covalent?

Covalent

Isomers

compounds that have the same molecular formula but different structures

Constitutional isomers

different compounds have the same molecular formula But differ in the sequence in which their atoms are bonded – that is, their connectivity

Dash structures

have lines that show bonding electron pairs, and include elemental symbols for all atoms in a molecule

What do dash structural formulas show

connectivity

In a bond line formula what does each line represent

a bond

What does each bend in a bond line formula represent

a carbon

When is the only time a C is written in a bond line formula

when there is a CH3 at the end of a chain

What do we infer about H in bond line formulas

that there are as many needed to fill the valence shell of the carbon

What happens if there is an element besides C or H in a bond line formula

it is written in the appropriate location

What does a straight bond line convey

the molecule lies within the plane of the paper

Carbon with 4 single bonds

tetrahedral

Carbon with a double bond

trigonal planar

Carbon with a triple bond

linear

When is a resonance structure more stable:

when it has more covalent bonds,

when it has less charge separation,

when all atoms have full valence shells

What is a hybrid structure

combined structure of all resonance structures

What is a wave function

different energy states for electrons

What is an energy state

sublevel where one or two electrons can reside

Constructive interference

when wave functions with the same phase sign interact : reinforcing effect: amplitude increases

Destructive interference

wave functions with opposite phase signs interact: subtractive effect: amplitude goes 0 or changes signs

What does it mean if the wave function is high

you have high probability of finding an electron there and the electron probability density is large

Orbital

region of space where probability of finding an electron is high

Atomic orbitals

plots of the square of a wave function in 3-D. They create the s, p, d orbital shapes

What shape are s orbitals

shperes

what sha[es are p orbitals

double lobed

What does 2s orbitals have

a sphere with an inner nodal surface with the square of a wave function being negative

What is the phase sign of a 2p wave function

one + and one -

What orbitals have the lowest energy

1s

Degenerate orbitals

orbitals of equal energy

Aufbau principle

lowest orbitals are filled first

Pauli exclusion principle

maximum of 2 electrons are in each orbital

Hunds rule

when orbitals have equal energy ( 3 2p orbitals) then each gets one electron

Atomic orbital

region of space where one or two electrons of an isolated atom are likely to be found

Molecular orbital

the space where One or two electrons of a molecule are likely to be found

Bonding molecular orbital

Results when two orbitals of the same phase overlap

Anti-bonding molecular orbital

Results when two orbitals of the opposite phase overlap

What are all single bonds

sigma bonds

Alkenes

hydrocarbons whose molecules contain a carbon-carbon double bond

Node

 region where the wave function = 0

What does the number of molecular orbitals always equal

the number of atomic orbitals

Hybrid atomic orbitals

obtained by mixing wave functions for orbitals of different types

Hybridizing three p and one s =

 four sp^3

Hybridizing two p and one s =

  three sp^2

Hybridizing one p and one s =

two sp

Sigma bond

 type of single bond where electron density has circular symmetry when viewed along bond axis

Pi bond:

when two p orbitals overlap sideways