Chemistry and

Organic Chemistry

Non-water part of living

things are 98% CHNOPS

• Carbon

• Hydrogen

• Oxygen

• Nitrogen

• Phosphorus

• Sulfur

The smallest particle of an element is an atom Different elements have different types of atoms

An atom is made up of protons and neutrons located in a central nucleus

• The nucleus is surrounded by electrons

In an uncharged atom, the number of electrons equals the number of protons.

Electrons are arranged in shells. The outermost shell determines the chemical

properties of an atom. In most atoms, a full outer shell can hold eight

electrons.

• Atoms whose shells are not full tend to interactwith other atoms and gain, lose, or shareelectrons

Figure 2.6

HYDROGEN (H)

Atomic number = 1

CARBON (C)

Atomic number = 6

NITROGEN (N)

Atomic number = 7

OXYGEN (O)

Atomic number = 8

Electron

Outermost electron shell (can hold 8 electrons)

First electron shell (can hold 2 electrons)

Element Symbol Atomic

number

Electrons to

share = number

of covalent

bonds

Molecule formed

with hydrogen

Hydrogen H 1

Oxygen O 8

Nitrogen N 7

Carbon C 6

Element Symbol Atomic

number

Electrons to

share = number

of covalent

bonds

Molecule formed

with hydrogen

Hydrogen H 1 1

Oxygen O 8

Nitrogen N 7

Carbon C 6

Element Symbol Atomic

number

Electrons to

share = number

of covalent

bonds

Molecule formed

with hydrogen

Hydrogen H 1 1 H2 H H

Hydrogen

molecule

Oxygen O 8

Nitrogen N 7

Carbon C 6

• Atoms whose shells are not full tend to interactwith other atoms and gain, lose, or shareelectrons

Figure 2.6

HYDROGEN (H)

Atomic number = 1

CARBON (C)

Atomic number = 6

NITROGEN (N)

Atomic number = 7

OXYGEN (O)

Atomic number = 8

Electron

Outermost electron shell (can hold 8 electrons)

First electron shell (can hold 2 electrons)

Element Symbol Atomic

number

Electrons to

share = number

of covalent

bonds

Molecule formed

with hydrogen

Hydrogen H 1 1 H2 H H

Hydrogen

molecule

Oxygen O 8 1, 2, 3,

4, or 5 ?

Nitrogen N 7

Carbon C 6

Clicker question How many bonds does oxygen form?

Element Symbol Atomic

number

Electrons to

share = number

of covalent

bonds

Molecule formed

with hydrogen

Hydrogen H 1 1 H2 H H

Hydrogen

molecule

Oxygen O 8 2

Nitrogen N 7

Carbon C 6

Element Symbol Atomic

number

Electrons to

share = number

of covalent

bonds

Molecule formed

with hydrogen

Hydrogen H 1 1 H2 H H

Hydrogen

molecule

Oxygen O 8 2 H20 H H

water O

Nitrogen N 7

Carbon C 6

• Atoms whose shells are not full tend to interactwith other atoms and gain, lose, or shareelectrons

Figure 2.6

HYDROGEN (H)

Atomic number = 1

CARBON (C)

Atomic number = 6

NITROGEN (N)

Atomic number = 7

OXYGEN (O)

Atomic number = 8

Electron

Outermost electron shell (can hold 8 electrons)

First electron shell (can hold 2 electrons)

Element Symbol Atomic

number

Electrons to

share = number

of covalent

bonds

Molecule formed

with hydrogen

Hydrogen H 1 1 H2 H H

Hydrogen

molecule

Oxygen O 8 2 H20 H H

water O

Nitrogen N 7 1, 2, 3,

4, or 5?

Carbon C 6

Clicker question How many bonds does nitrogen form?

Element Symbol Atomic

number

Electrons to

share = number

of covalent

bonds

Molecule formed

with hydrogen

Hydrogen H 1 1 H2 H H

Hydrogen

molecule

Oxygen O 8 2 H20 H H

water O

Nitrogen N 7 3

Carbon C 6

Element Symbol Atomic

number

Electrons to

share = number

of covalent

bonds

Molecule formed

with hydrogen

Hydrogen H 1 1 H2 H H

Hydrogen

molecule

Oxygen O 8 2 H20 H H

water O

Nitrogen N 7 3 H

NH3 N H

Ammonia H

Carbon C 6

• Atoms whose shells are not full tend to interactwith other atoms and gain, lose, or shareelectrons

Figure 2.6

HYDROGEN (H)

Atomic number = 1

CARBON (C)

Atomic number = 6

NITROGEN (N)

Atomic number = 7

OXYGEN (O)

Atomic number = 8

Electron

Outermost electron shell (can hold 8 electrons)

First electron shell (can hold 2 electrons)

Element Symbol Atomic

number

Electrons to

share = number

of covalent

bonds

Molecule formed

with hydrogen

Hydrogen H 1 1 H2 H H

Hydrogen

molecule

Oxygen O 8 2 H20 H H

water O

Nitrogen N 7 3 H

NH3 N H

Ammonia H

Carbon C 6 1, 2, 3,

4, or 5?

Clicker question How many bonds does carbon form?

Element Symbol Atomic

number

Electrons to

share = number

of covalent

bonds

Molecule formed

with hydrogen

Hydrogen H 1 1 H2 H H

Hydrogen

molecule

Oxygen O 8 2 H20 H H

water O

Nitrogen N 7 3 H

NH3 N H

Ammonia H

Carbon C 6 4

Element Symbol Atomic

number

Electrons to

share = number

of covalent

bonds

Molecule formed

with hydrogen

Hydrogen H 1 1 H2 H H

Hydrogen

molecule

Oxygen O 8 2 H20 H H

water O

Nitrogen N 7 3 H

NH3 N H

Ammonia H

Carbon C 6 4 CH4 H

Methane H C H

H

• Atoms in a covalently bonded molecule mayshare electrons equally, creating a nonpolarmolecule

• If electrons are shared unequally, a polarmolecule is created

• In a water molecule, oxygen exerts a strongerpull on the shared electrons than hydrogen

–This makes the oxygenend of the moleculeslightly negativelycharged

–The hydrogen end ofthe molecule isslightly positivelycharged

–Water is therefore apolar molecule

(Ğ) (Ğ)

(+)(+)

• The charged regionson water moleculesare attracted to theoppositely chargedregions on nearbymolecules

–This attractionforms weak bondscalled hydrogenbonds

Hydrogen bond

Consequences of water’s

H bonding

• Surface tension

• Capillary action

• High specific heat

• Takes much energy to melt and to

evaporate

• Ice floats Simple parts, new qualities - emergent

properties.

• Molecules in ice are farther apart than those inliquid water

Hydrogen bond Hydrogen bond

LIQUID WATER

Hydrogen bonds constantly

break and re-form

ICE

Hydrogen bonds are stable

Organic Chemistry

The chemistry of carbon

Depicting

methane

CH4

Carbon bonds to other carbons

H H

H C C H

H H

H H H

H C C C H

H H H

Propane C3H8

Ethane C2H6

H H H H H H H

H C C C C C C C H

H H H H H H H

And much longer chains

Ethylene C2H4

Carbon can make double bonds

C C

H

H H

H

H C C H

Acetylene C2H2

=Ethyne

Carbon can make triple bonds

Carbon chains can make rings

C C

C C

C C H

H

H

H

H H H

H

H

H

H H

Cyclohexane

C6H12

Ways of depicting propane

H H H

H C C C H

H H H

C C C

“Carbon backbone”

Assumes the correct number of

hydrogens are attached.

C3H8

Chemical formula

Gives no structural information.

CH3-CH2-CH3

Isomers: Same formula, different structure

H H H H

H C C C C H

H H H H

Butane

C4H10 C C C C

Isobutane

C4H10

C C C

C

C

C C C

Isobutane,

other views,

rotated or

bent differently.

C

C C

C

How many pentane isomers?

Pentane: C5H12

Bigger molecules, many possible isomers

A. 2

B. 3

C. 4

D. 5

E. 6

Clicker question

There are three pentane isomers, C5H12

c-c-c-c-c

c c-c-c-c

c c-c-c

c

c-c-c-c c

c c-c-c

c

c c

c-c-c

c c-c-c-c

c-c c c

c

Not

C5H10

1.

2.

3.

=

= = =

A chiral molecule has 2 mirror images

These are called stereoisomers or

enantiomers Same formula and same structure,

but like right and left hands.

“R” stands for

the rest of the

molecule