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25 Cards in this Set

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-Name 2 types of chemical bonds.
-What is the difference between these two types of bonds and which bond is the strongest?
1. covalent
2. non-covalent
-covalent bonds are formed when atoms SHARE a pair of electrons and they are STRONGER than non-covalent
-non-covalent bonds do NOT share e-
-Are all covalent bonds of equal strength? Discuss.
-Double (covalent) bonds are stronger than single bonds and triple bonds are even stronger (requiring more energy to break the bond)
Name 4 types of non-covalent bonds.
1.electrostatic bonds (include ionic bonds)
2. van der Waals forces
3. hydrophobic interactions
4. hydrogen bonds
-What is an electrostatic bond?
-Give an example.
-A type of non-covalent bond between atoms which involves a complete TRANSFER of electrons (resulting from an attraction between charged groups, i.e. a cation and anion)
-NaCl = ionic bond (no charge)
-What is Coloumb's Law?
-Electrical attraction Force of atoms is described by the equation
F=(k)(q1)(q2) / (r2)(D) ; What is D?
-opposite ions charges attract and like charges repel
-D is a constant that depends on the medium (the higher the D, the weaker the attractive forces... water has a high D, thus resulting in dissolution)
-Name 2 types of chemical bonds.
-What is the difference between these two types of bonds and which bond is the strongest?
1. covalent
2. non-covalent
-covalent bonds are formed when atoms SHARE a pair of electrons and they are STRONGER than non-covalent
-non-covalent bonds do NOT share e-
-Are all covalent bonds of equal strength? Discuss.
-Double (covalent) bonds are stronger than single bonds and triple bonds are even stronger (requiring more energy to break the bond)
Name 4 types of non-covalent bonds.
1.electrostatic bonds (include ionic bonds)
2. van der Waals forces
3. hydrophobic interactions
4. hydrogen bonds
-What is an electrostatic bond?
-Give an example.
-A type of non-covalent bond between atoms which involves a complete TRANSFER of electrons (resulting from an attraction between charged groups, i.e. a cation and anion)
-NaCl = ionic bond (no charge)
-What is Coloumb's Law?
-Electrical attraction Force of atoms is described by the equation
F=(k)(q1)(q2) / (r2)(D) ; What is D?
-opposite ions charges attract and like charges repel
-D is a constant that depends on the medium (the higher the D, the weaker the attractive forces... water has a high D, thus resulting in dissolution)
-Name 2 reasons why water is such an important solvent.
1. polarity
2. non-linear shape
Both contribute to a distribution of electrons/charge
-The tendency of non-polar molecules to cluster together in water is referred to as what?
-Do hydrophobic molecules stick together in water because of their affinity to each other?
-the hydrophobic effect (hydrophobic = nonpolar)
-NO! They stick together due to the affinity of water to other water molecules (polarity... even in the liquid form water is relatively ordered)
-What is unique about hydrogen bonds?
-Why is this hydrogen bonding important?
-hydrogen (although bonded to another atom, O for example) will have a slightly + charge, thus attracting atoms/compounds that have a slight - charge
-hydrogen bonds are CRUCIAL to the 3D structure of biological macromolecules, such as DNA
What are van der Waals forces?
-an attractive force between any two atoms that occurs when they are in close proximity to each other (<4 Anstoms)
-Substances that minimize changes in H+ and OH- concentrations are called what?
-Most buffers are what type of molecules?
-buffers (minimize changes in pH)
-weak acids or weak bases (they can bind reversibly with hydrogen ions thus accepting H+ from soln when they are in excess and donating them when the soln in depleted)
-Name 2 reasons why water is such an important solvent.
1. polarity
2. non-linear shape
Both contribute to a distribution of electrons/charge
-The tendency of non-polar molecules to cluster together in water is referred to as what?
-Do hydrophobic molecules stick together in water because of their affinity to each other?
-the hydrophobic effect (hydrophobic = nonpolar)
-NO! They stick together due to the affinity of water to other water molecules (polarity... even in the liquid form water is relatively ordered)
-What is unique about hydrogen bonds?
-Why is this hydrogen bonding important?
-hydrogen (although bonded to another atom, O for example) will have a slightly + charge, thus attracting atoms/compounds that have a slight - charge
-hydrogen bonds are CRUCIAL to the 3D structure of biological macromolecules, such as DNA
What are van der Waals forces?
-an attractive force between any two atoms that occurs when they are in close proximity to each other (<4 Anstoms)
-Substances that minimize changes in H+ and OH- concentrations are called what?
-Most buffers are what type of molecules?
-buffers (minimize changes in pH)
-weak acids or weak bases (they can bind reversibly with hydrogen ions thus accepting H+ from soln when they are in excess and donating them when the soln in depleted)
-Which weaks acid is important physiologically to maintiain the body's correct pH range?
-carbonic acid - can accept or donate a H+ during fluctuations in pH
-What two things always happen during a chemical reaction?
1. Energy remains constant
2. A process will occur spontaneously if total entropy is increased
-Discuss Gibb's free energy and what happen if G is <, >, or = zero
-if G is negative, then a reaction can occur spontaneously
-if G is zero, then there is no net change (equilibrium)
-if G is positive, then energy is needed to drive the reaction
-Although Gibb's free energy is less than zero, some reactions occur slowly (G is independent of RATE of reaction)... what can help a reaction rate?
-catalysts, such as enzymes
-If a reaction is considered +, heat energy must be absorbed to fuel the reaction... this is referred to as what type of reaction?
-What is an exothermic reaction?
-Endothermic
-a reaction in which heat energy is released (the product contains less energy than the reactants and energy is liberated as heat)