Organic Chemistry Ch.1

Why are organic chemicals so important?

They are found in proteins (hair, skin, muscles), DNA, (genetic heritage), food (carbs, proteins, fats, oils), medicines (Ibuprofen, Tylenol), and construction (vinyl sidings, fences, PVC pipes)

What do most organic compounds contain? How do simple molecules form?

mostly carbon, also includes nitrogen, oxygen, fluorine, phosphorus, sulfur, chloride, bromine, iodine

the carbon atom can bond to another carbon, and to other atoms

What does a dashed and solid line create when looking at a diagram? What does it mean?

Chiral Center (has 4 different groups connected-either S or R form)

Atomic Number

Z

Number of protons or electrons

Atomic Mass

A

Number of protons and neutrons in the nucleussotoI

Isotopes

have the same atomic number, but different mass number

When two atoms interact, exactly what reacts/happens?

the electrons that reside in the orbitals (there 90-95% of the time) reacts and leads to bond formation

What are orbitals made of?

Electron Shells (1,2,3/K,L,M)

*the further these shells are from the nucleus, the larger its size and energy

How do calculate the max number of electrons in the different electron shells?

2n² where n=the shell number

e.g. 4th shell: 2(4)²=32

What are electron shells made of?

Subshells (s, p, d, and f orbitals)

*the arrows/lines are degenerate orbitals

Electron configuration

arrangement of electrons in atomic orbitals of an atom

What are the 3 rules of electron configuration?

Aufbau Principle: fill up the lowest-energy orbitals first

Pauli Exclusion Principle: only 2 electrons can occupy an orbital and be of opposite spin

Hund’s Rule: If 2 or more empty orbitals of equal energy are available, one electrons occupies each with parallel spins until all orbitals are half-full

How do you figure out how many valence electrons there are?

add up the last row’s squares

3s²3^4 2+4=6

What is the most common bond in organic chemistry?

covalent: formed by electron sharing

*orbitals must overlap for electron sharing to occur more effectively

Valence Shell

Valence Electrons

outermost shell

electrons in the outermost shell (these are what participate in chemical bonding)

What is the Valence Bond Theory?

bonding atoms must approach each other close enough (bond length) to facilitate stable bonding)

When do sigma bonds occur?

Head on overlap

s-s, s-p, s-sp^x (hybrid orbital), p-p, p-sp^x, sp^x-sp^x

*each bond is different bc one may require more energy to break than the other

When do pi bonds occur?

sideways overlap

p-paW

What is found in single/double/triple bonds?

single: 1 sigma

double: 1 sigma, 1 pi

triple: 1 sigma (middle), 2 pi

How do you figure how many bonds an atom will have?

calculate how many electrons an atom will need to lose or gain to get to the noble gas

e.g. B=3

Hybridization

the process of mixing atomic orbitals to form new ones

s can mix with one, two, or three p’s

In the image for a hybrid orbital (sp^x) why is each side a different size?

if, for example, sp3, there are 3 p’s combined, so bigger

When you have sp³, what does the 3 indicate? Also how many orbitals are present and what’s the percentage of each?

tells you your mixing with all three p orbitals

4 orbitals (25% s; 75%p)

How can you determine hybridization?

count the number of bonds (remember a double bond really just counts as one)

*if a space is left unoccupied, it is an unhybridized orbital e.g. sp² has one unhybridized p orbital

What are the bond angles for each hybridization?

sp=180º

sp²=120º

sp³=109.5

sp³d=90º/120º

sp³d²=90º

What is the type of hybridization on a methyl carbocation? methyl carbanion?

H3C+ sp² bc they + doesn’t count as an electron group

CH3- sp³ bc of lone pair of electrons

How to do an electron dot structure?

Count up all valence electrons

figure out how many bonds central atom can form, write them in and make sure octet is followed, then put in lone electrons where needed

*remember to first look at how many bonds something can have, write them out, then see if any lone pairs (these do not count as bonds and will exist if there are more valence electrons)

*lone pairs count as bonds for hybridization

What are the different kinds of organic structures?

condensed/semi-condensed (normal: CH3CH2) electron-dot ( H..C)

line-bond (H—C—H)

skeletal (^ *do not include carbon/hydrogens)

molecular (C3H8)

make sure to follow octet

How do you know if something is a central atom?

cannot be hydrogen, halogen, or metals