Lecture focus questions; Chemistry Flashcards
What is the difference between Ionic & Covalent bonds?
- 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
How do oppositely charged atoms interact?
-By electrostatic attraction
What type of bonds do C,H,O,N form in biological molecules and how many bonds can they make?
- They form covalent bonds
- C makes 4 bonds, H makes 1 bond, O can make 2 bonds, N can make 3 bonds
What is the difference between polar & non-polar covalent bonds?
- Non-polar covalent bonds involve an EQUALISH share of electrons
- Polar covalent bonds involve an UNEQUAL share of electrons
How are the polarity of covalent bonds determined?
- 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
What are Functional Groups?
-They are groups of 2-6 atoms that form modules in making organic molecules
How can you distinguish a Polar functional group from a Non-polar functional group?
- A polar functional group has C,H bonded to N or O
- A non-polar functional group has ONLY C & H atoms
What are the 3 different types of bonding?
- Ionic
- Covalent
- Non-covalent
What is Non-covalent bonding?
- It creates effective but reversible interactions
- The 2 kinds are Vanderwaal & H or H- bonding
What are the 2 key characteristics of Van der Waals bonding?
- It has an attractive & repulsive component
- It works to keep atoms at their most favorable distance
How does Hydrogen bonding arise?
-It arises when hydrogen is covalently bonded to a more electronegative atom
What is the donor & acceptor in hydrogen bonding?
- 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
What must be the arrangement in order to form a hydrogen bond?
-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
How does hydrogen bonding affect the properties of water?
- 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
How does the Hydrophobic effect occur?
- 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
What is the Self-Ionization of water?
- 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
How is Self-Ionization related to acids & bases?
- 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
How is pH defined?
- It’s defined as -log[H+]
- This expression is used to convert scientific notation w/ exponents into small number
How do acids & bases change the pH of a solution?
- 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
What is an example of an organic acid?
-It is compounds containing the carboxylic acid functional group= COOH which is neutral in acidic pH and basic in negatively charged pH
What is an example of an organic base?
-It is compounds pertaining to the amine functional group= NH2 which is neutral in at basic pH and positively charged at acidic pH
What is the difference between Acid-base reactions & Redox reactions?
- 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
How can you tell if an organic compound is more reduced than others?
- The more reduced ones have more hydrogen atoms & fewer/ no oxygen atoms
- The hydrogen atoms are covalently & stably bound to carbon atoms
How can you tell if an organic compound is more oxidized than others?
-They’ll have fewer/ no hydrogen atoms and more oxygen atoms
