Chapter 4 - Carbon and Molecular Diversity

Question 1

Formation of Bonds with Carbon

Answer 1

• Carbon has 6 electrons; 2 in the first shell and 4 in the valence shell
  - Usually completes its valence by sharing 4 covalent bonds
  • When carbon atoms form 4 single covalent bonds, the arrangement of the 4 orbitals(space for electrons to float within) angle to form an imaginary tetrahedron
  • But when two carbon atoms are joined by a double bond, the bonds are in the same plane, so the atoms which joined to the carbons fall into the same plane

Question 2

Rules for Bonding for CO2

Answer 2

• In Co2, two oxygens are double bonded to carbon
  • The two double lines have the same number of shared electrons as 4 single bonds, completing the valence shell of the carbon
• Co2 is often called inorganic because it is simple and lacks hydrogen

Question 3

Rules of Bonding for Urea CO(NH2)2

Answer 3

• It is an organic compound found in urine
  
  • Carbon is participating in both single and double bonds to fill its valence shell

Question 4

Carbon Skeleton

Answer 4

the backbone of molecules and are the chains which form the basis of most organic molecules

- Can vary in length and can be straight, branched, or closed rings and can have single or double bonds
- The variation in carbon chains is important for molecular diversity and complexity

Question 5

Hydrocarbons

Answer 5

an organic molecule consisting of only hydrogen and carbon atoms
- The major components of petroleum and fats
- Not prevalent in most livign organisms
- Can undergo reactions which release a relatively large amount of energy

Question 6

Isomers

Answer 6

one of two or more compounds which have the same number of atoms of the same elements but different structures and therefore different properties

• structural, geometric or Enantiomers

Question 7

Types of Isomers: Structural

Answer 7

a compound which has the same molecular formula but differs due to the covalent arrangement of their atoms
- The bigger the carbon skeleton, the more the possible isomers
- Can also differ in the location of double bonds

Question 8

Types of Isomers: Geometric

Answer 8

have the same molecular formular and covalent bonds between atoms but differ in the spatial arrangement of the atoms due to the inflexibility of double bonds
- Occurs when a carbon is double bonded to a carbon each with their own two atoms, then distinct cis-trans isomers are possible

Question 9

Types of Geometric Isomers

Answer 9

Cis Isomers: the two R groups are on the same side of the carbon-to-carbon double bond

Trans Isomers: the two R groups are on opposite sides of the carbon-to-carbon double bond

Question 10

Types of Isomers: Enantiomers

Answer 10

isomers which are mirror images of each other but differ in shape due to the presence of an asymmetric carbon
- Similar to hands and gloves, the ‘left handed’ molecule cant do the job of the ‘right handed’ molecule

Question 11

Functional Groups

Answer 11

chemical groups(a specific configuration of atoms) which are directly involved in Chemical Reactions

Question 12

Hydroxyl Group

Answer 12

-OH

• polar(electronegative O) and forms hydrogen bonds with water and helps dissolve compounds
  
  • Types of alcohol molecules(ending in -ol)

Question 13

Carbonyl Group

Answer 13

C=O

• fall either within Carbon Skeletons (ketones)
  
  • Fall at the end of Carbon Skeletons (aldehydes)

Question 14

Carboxyl Group

Answer 14

OH- C=O

• acts as an acid(can donate H+) because of polar bond between O and H creating -1 charge
  
  • Found in Any type of acid

Question 15

Amino Group

Answer 15

NH2

• acts as a base and can pick up H+ from surrounding solutions creating a +1 charge

Question 16

Sulfhydryl Group

Answer 16

-SH

• two can form crosslinks which stabilize protein structures(E.g. help DNA keep its helix shape by forming bonds)
  
  • Named Thiols

Question 17

Phosphate Group

Answer 17

O-P=O - O2-

• confers on to molecules the ability to react with water(gives energy)
  
  • adds negative charges when inside a chain
  • adds 2 negative charges when at the end of a chain

Question 18

Methyl Group

Answer 18

C - H3

• Doesn’t provide properties but serves as recognizable tags on biological molecules to signal ‘self DNA’