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25 Cards in this Set
- Front
- Back
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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- |
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-Are all covalent bonds of equal strength? Discuss.
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-Double (covalent) bonds are stronger than single bonds and triple bonds are even stronger (requiring more energy to break the bond)
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Name 4 types of non-covalent bonds.
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1.electrostatic bonds (include ionic bonds)
2. van der Waals forces 3. hydrophobic interactions 4. hydrogen bonds |
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-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) |
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-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) |
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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- |
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-Are all covalent bonds of equal strength? Discuss.
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-Double (covalent) bonds are stronger than single bonds and triple bonds are even stronger (requiring more energy to break the bond)
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Name 4 types of non-covalent bonds.
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1.electrostatic bonds (include ionic bonds)
2. van der Waals forces 3. hydrophobic interactions 4. hydrogen bonds |
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-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) |
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-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) |
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-Name 2 reasons why water is such an important solvent.
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1. polarity
2. non-linear shape Both contribute to a distribution of electrons/charge |
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-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) |
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-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 |
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What are van der Waals forces?
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-an attractive force between any two atoms that occurs when they are in close proximity to each other (<4 Anstoms)
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-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) |
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-Name 2 reasons why water is such an important solvent.
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1. polarity
2. non-linear shape Both contribute to a distribution of electrons/charge |
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-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) |
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-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 |
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What are van der Waals forces?
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-an attractive force between any two atoms that occurs when they are in close proximity to each other (<4 Anstoms)
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-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) |
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-Which weaks acid is important physiologically to maintiain the body's correct pH range?
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-carbonic acid - can accept or donate a H+ during fluctuations in pH
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-What two things always happen during a chemical reaction?
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1. Energy remains constant
2. A process will occur spontaneously if total entropy is increased |
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-Discuss Gibb's free energy and what happen if G is <, >, or = zero
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-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 |
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-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?
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-catalysts, such as enzymes
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-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) |
