Chapter 4.4: Organic and Biochemical Compounds

Organic Compounds

• Covalently bonded• Carbon compounds• Almost always contain hydrogen

Organic molecules contain carbon, usually hydrogen,

And assorted other atoms may be included, likeOxygen, nitrogen, sulfur and phosphorus(notice all are nonmetals, so they form covalent bonds)

Carbon has four valence electrons

• So it will make four bonds with other atoms willing to share their electrons.

• Including other carbon atoms!

Naming rules

Number of carbons

• Meth- 1

• Eth- 2

• Prop- 3

• But- 4

• Pent- 5

• Hex-6

Naming for different types of bonds

• -ane only carbon-carbon single bonds

• -ene contains a carbon-carbon double bond

• -yne contains a carbon-carbon triple

bond

Remember

• The term “single bond” just means that two atoms are sharing ONE (single) pair of electrons. Two hydrogen atoms share their electrons. You can write this as

• H – H where the single black line shows that the atoms are sharing only one pair of electrons.

• Double bond means two pairs of shared electrons.

And of course triple bond would be three pairs of shared electrons

• Like the bonds in a nitrogen molecule (N2)

Alkanes

• Only single covalent bonds.

• Methane, CH4 Ethane, C2H6

Alkanes:Single carbon-carbon bonds

• The two carbon atoms are only sharing one pair of electrons, one from each of the two carbon atoms.

Propane

• The “prop-” means three carbons

• And the “-ane” means all single bonds

Alkenes

• Double bonds (two carbons are sharing two pairs – four atoms)

Propene and Butene

•

ethyne = triple bond

• Two carbons sharing 3 pairs (6 electrons)

propyne

Alcohols have an –OH group

• One of the hydrogens is replaced by an –OH group. Since there are two carbons, this is ethanol.

Polymers

• Big molecules made of repeating units.

• The units are attached to one another by bonds, like beads strung together on a necklace.

Polyethene

• Poly means “many”• So it’s a large

molecule made up of a series of “ethenes” (C2H4)

• Plastic in soda bottles, etc. made of long noodle-like chains of these units.

• Each unit = monomer

Polymerization

• Free Radical Propagation

• click here to see how polymers are formed from individual ethene molecules

Shape of polymer determines properties.

• Polyethene isn’t elastic, so when you crush bottle it doesn’t “bounce” back.

• This is because the long noodlelike chains can be bent easily, but they slide and slip instead of springing back into shape, like spaghetti noodles that roll around your plate.

Elasticity

• Cross-linked (like chain link fences or tennis nets) are flexible, but snap back into shape.

• Molecules in a rubber band are examples.

Carbohydrates

• Glucose is a carbohydrate.

Large polymers of sugars are carbohydrates,often called “starch”.

Carbohydrates can be 100's of sugars long.

Body breaks the larger molecules into smaller glucose “units” again

during digestion.

Proteins

• Made up of repeating units called

• amino acids.

•CHON and sometimes S!

DNA

• Adenine and • Thymine

• Cytosine and • Guanine

• CHONP