Lecture focus questions; Chemistry

Question 1

What is the difference between Ionic & Covalent bonds?

Answer 1

• Ionic bonds involve the TRANSFER of one or more electrons to another atom to create stable, positive & negative ions
• Covalent bonds involve SHARING electrons between 2 atoms

Question 2

How do oppositely charged atoms interact?

Answer 2

-By electrostatic attraction

Question 3

What type of bonds do C,H,O,N form in biological molecules and how many bonds can they make?

Answer 3

• They form covalent bonds

- C makes 4 bonds, H makes 1 bond, O can make 2 bonds, N can make 3 bonds

Question 4

What is the difference between polar & non-polar covalent bonds?

Answer 4

• Non-polar covalent bonds involve an EQUALISH share of electrons
• Polar covalent bonds involve an UNEQUAL share of electrons

Question 5

How are the polarity of covalent bonds determined?

Answer 5

• By the electronegativities of the atom involved
• If the electronegativity difference is less than 0.5 then it is non-polar
• If the electronegativity difference is more or equal to 0.5 then it is polar

Question 6

What are Functional Groups?

Answer 6

-They are groups of 2-6 atoms that form modules in making organic molecules

Question 7

How can you distinguish a Polar functional group from a Non-polar functional group?

Answer 7

• A polar functional group has C,H bonded to N or O

- A non-polar functional group has ONLY C & H atoms

Question 8

What are the 3 different types of bonding?

Answer 8

• Ionic
• Covalent
• Non-covalent

Question 9

What is Non-covalent bonding?

Answer 9

• It creates effective but reversible interactions

- The 2 kinds are Vanderwaal & H or H- bonding

Question 10

What are the 2 key characteristics of Van der Waals bonding?

Answer 10

• It has an attractive & repulsive component

- It works to keep atoms at their most favorable distance

Question 11

How does Hydrogen bonding arise?

Answer 11

-It arises when hydrogen is covalently bonded to a more electronegative atom

Question 12

What is the donor & acceptor in hydrogen bonding?

Answer 12

• The donor is the electronegative atom that’s covalently bonded to hydrogen which donates a hydrogen bond to the acceptor
• The acceptor is the other electronegative atom

Question 13

What must be the arrangement in order to form a hydrogen bond?

Answer 13

-The donor, the hydrogen that’s attached to the donor & and the acceptor MUST be in a STRAIGHT line in order to form a hydrogen bond

Question 14

How does hydrogen bonding affect the properties of water?

Answer 14

• The H bonding of water helps give water its cohesion & boiling point
• Since H bonds are reversible, it also allows water to still be a liquid & not solidify into ice

Question 15

How does the Hydrophobic effect occur?

Answer 15

• It occurs when non-polar molecules don’t fuck with polar water
• SO non-polar molecules will gang up on themselves & disassociating with the polar water as LITTLE as possible

Question 16

What is the Self-Ionization of water?

Answer 16

• It is the formation of H+ and OH- bonds from neutral water molecules
• This self-ionization goes on spontaneously BUT only a small portion of molecules are ionized at any given time

Question 17

How is Self-Ionization related to acids & bases?

Answer 17

• The product of H+ ions and OH- ions is ALWAYS 10^14
• And acids & bases are solutes in water that alter the amounts of H+ ions and OH- ions
• SO when an acid increases the concentration of H+ ions, OH- ions will accommodate to keep 10^14 constant

Question 18

How is pH defined?

Answer 18

• It’s defined as -log[H+]

- This expression is used to convert scientific notation w/ exponents into small number

Question 19

How do acids & bases change the pH of a solution?

Answer 19

• Well the pH at 7 is neutral= same amount of H+ ions and OH-
• Acids increase the proton concentration which DECREASES the pH
• Bases decrease the proton concentration which INCREASES the pH

Question 20

What is an example of an organic acid?

Answer 20

-It is compounds containing the carboxylic acid functional group= COOH which is neutral in acidic pH and basic in negatively charged pH

Question 21

What is an example of an organic base?

Answer 21

-It is compounds pertaining to the amine functional group= NH2 which is neutral in at basic pH and positively charged at acidic pH

Question 22

What is the difference between Acid-base reactions & Redox reactions?

Answer 22

• Acid-base reaction transfers protons (H+) between molecules at a faster pace bc of the lower activation energy barrier inside cells & changes in pH
• Redox reaction transfers electrons between molecules at a slower pace bc of the higher activation energy barrier. They involve breaking/making covalent bonds &; require the help of enzymes or catalysts

Question 23

How can you tell if an organic compound is more reduced than others?

Answer 23

• The more reduced ones have more hydrogen atoms & fewer/ no oxygen atoms
• The hydrogen atoms are covalently & stably bound to carbon atoms

Question 24

How can you tell if an organic compound is more oxidized than others?

Answer 24

-They’ll have fewer/ no hydrogen atoms and more oxygen atoms