What percent of our body weight comes from water?
60%
Name the three areas where our body keeps the water and their relative %.
40% intracellular water, 15% interstitial water, and 5% water in circulatory system.
Water's electronic arrangement
Water has tetrahedral geometry because of its electronic structure. Water is polar, meaning it has an uneven distribution of charge.
Oxygen has a partial _____ charge; Hydrogen has a partial _____ charge.
negative; positive.
Each H bond has a lifespan of what?
10^-12 sec
The lifespan of H-bond is incredibly short, what does that say about the property of water?
It's dynamic (but still strong), always changing.
What gives water its surface tension?
Hydrogen bonding
If hydrogen bonds are always breaking, how come the surface tension can still exist?
They always reform the bonds.
What gives water molecule its polarity?
Electronegativity
Why does frozen beer break the bottle?
Because ice is more spacious. Ice crystal lattice
What is a hydrogen bond?
A hydrogen bond is a noncovalent interaction between a molecule containing an electronegative atom (such as O or N and sometimes S) and another molecule containing an electropositive hydrogen.
How do you spot a hydrogen bond?
A hydrogen is bound to oxygen, nitrogen, or sulfur and it has to be partially stripped.
What causes a hydrogen bond?
Partial stripping of hydrogen gives a dipole dipole moment which gives a partial positive charge.
Based on electronegativity, which element forms a stronger H-bond, O or N?
O, because oxygen is more electronegative.
The hydrogen bond donor is the __ and the hydrogen bond acceptor is _____.
H; S, O, or N.
What is the length of a covalent bond?
1 A
What is the length of an H-bond?
1.8 A
What is van der Waal radii?
The distance from its nucleus to its effective electronic surface.
Why can't a H-bond be any shorter?
Collision or electron shell, wants to get closer but can't.
T/F The hydrogen bonds in water are partially covalent.
False
T/F The hydrogen bonds in water are a type of electrostatic interaction?
True
T/F The hydrogen bonds in water are strong and therefor long-lived in solution.
False
T/F Hydrogen bonds in water are longer than covalent O-H bond.
True
T/F Hydrogen bonds in water are shorter than the sum of the van der waals radii of O and H.
True
Name the four molecular forces that keep atoms together.
Covalent, ionic, hydrogen, and van der walls.
Rank the four molecular forces in order of decreasing strength.
Covalent, ionic, hydrogen, and van der waals.
What is a dipole dipole interaction?
Dipole-dipole interaction is the interaction between two dipole molecules.
What causes a molecule to have a dipole property?
Molecular dipoles occur due to the unequal sharing of electrons between atoms in a molecule.
What are the two types of interactions that fall under the van der waal category?
Dipole dipole and london dispersion.
What causes London dispersion forces?
Irregular fluctuation within the molecule that lead to a momentary dipole moment.
Why is it that we should not dismiss/discount these weak forces?
Because there can be a lot of them. Don't just look at strength of bond, look at how many there are.
Why is water such a good solvent?
It can participate in hydrogen bonding so almost anything containing O, N, and S can interact with it. It is polar so it can interact with anything that are also polar or ionic. It has a relatively high dielectric constant.
What does the dielectric constant value of a solvent say about its property?
Its ability to shield the charges.
What solvent would you expect to be better at dissolving based on the dielectric chart?
The one with the highest dielectric constant.
What is hydrophobicity?
Nonpolar molecules such as oil are not miscible with polar solvents such as water. Water molecules avoid touching.
What is the hydrophobic effect?
The phenomenon by which non polar molecules aggregate to avoid contact with hydrophilic molecules, particularly water. The exclusion of non polar substances from an aqueous solution.
What is the leading force that drives the hydrophobic effect?
Entropy of water molecules/solvent.
What does amphiphilic mean?
Molecules that have both hydrophobic and hydrophilic portions.
What is a micelle?
A particle with a solvated surface and a hydrophobic core. Amphiphiles may form micelles as a result of amphiphilic molecules being added to water.
What is a vesicle?
Has a hydrophilic/water core. It forms to eliminate its solvent-exposed edges, the lipid bilayer tends to close up forming a vesicle.
What is a main function that the lipid bilayer does for the cell?
It is a barrier against diffusion.
In pure water, the more H+ you have the more what?
Acidic
Solutions in which H+ > 10^-7 M= ?
Acidic
Solutions in which H+ < 10^-7 M= ?
Basic
Which condition holds more H30+ ions, acid or base?
Acid
What is the difference between H+ and H30+ ions?
H+ represents H30+ but you'll never find it in nature.
How often does a water molecule spontaneously break up into its ionic form?
1 in 55.5 million
Strong acid
They disassociate completely in water (always single, never coupled up).
Weak acid
They disassociate partially. (Some are single form, some are coupled up).
The weakest acids are where on the chart?
On the bottom of the chart because pK=-log
What does pK describe?
An acid's tendency to ionize
What is the conjugate base of the weak acid H3BO3?
H2BO3- because it lost one proton and took on negative charge.
What is the conjugate base of H2BO3-?
HBO3^2-
What is the conjugate base of HBO3^2-?
BO3^3-
Which of the following would be the strongest acid?
The strongest acid has the smallest pK. Make sure to convert pH to pK.
All weak acids can be considered what?
A buffer
A buffer can be what of its pK?
1+ or 1- of its pK
What percent of our body weight comes from water?
60%
Name the three areas where our body keeps the water and their relative %.
40% intracellular water, 15% interstitial water, and 5% water in circulatory system.
Water's electronic arrangement
Water has tetrahedral geometry because of its electronic structure. Water is polar, meaning it has an uneven distribution of charge.
Oxygen has a partial _____ charge; Hydrogen has a partial _____ charge.
negative; positive.
Each H bond has a lifespan of what?
10^-12 sec
The lifespan of H-bond is incredibly short, what does that say about the property of water?
It's dynamic (but still strong), always changing.
What gives water its surface tension?
Hydrogen bonding
If hydrogen bonds are always breaking, how come the surface tension can still exist?
They always reform the bonds.
What gives water molecule its polarity?
Electronegativity
Why does frozen beer break the bottle?
Because ice is more spacious. Ice crystal lattice
What is a hydrogen bond?
A hydrogen bond is a noncovalent interaction between a molecule containing an electronegative atom (such as O or N and sometimes S) and another molecule containing an electropositive hydrogen.
How do you spot a hydrogen bond?
A hydrogen is bound to oxygen, nitrogen, or sulfur and it has to be partially stripped.
What causes a hydrogen bond?
Partial stripping of hydrogen gives a dipole dipole moment which gives a partial positive charge.
Based on electronegativity, which element forms a stronger H-bond, O or N?
O, because oxygen is more electronegative.
The hydrogen bond donor is the __ and the hydrogen bond acceptor is _____.
H; S, O, or N.
What is the length of a covalent bond?
1 A
What is the length of an H-bond?
1.8 A
What is van der Waal radii?
The distance from its nucleus to its effective electronic surface.
Why can't a H-bond be any shorter?
Collision or electron shell, wants to get closer but can't.
T/F The hydrogen bonds in water are partially covalent.
False
T/F The hydrogen bonds in water are a type of electrostatic interaction?
True
T/F The hydrogen bonds in water are strong and therefor long-lived in solution.
False
T/F Hydrogen bonds in water are longer than covalent O-H bond.
True
T/F Hydrogen bonds in water are shorter than the sum of the van der waals radii of O and H.
True
Name the four molecular forces that keep atoms together.
Covalent, ionic, hydrogen, and van der walls.
Rank the four molecular forces in order of decreasing strength.
Covalent, ionic, hydrogen, and van der waals.
What is a dipole dipole interaction?
Dipole-dipole interaction is the interaction between two dipole molecules.
What causes a molecule to have a dipole property?
Molecular dipoles occur due to the unequal sharing of electrons between atoms in a molecule.
What are the two types of interactions that fall under the van der waal category?
Dipole dipole and london dispersion.
What causes London dispersion forces?
Irregular fluctuation within the molecule that lead to a momentary dipole moment.
Why is it that we should not dismiss/discount these weak forces?
Because there can be a lot of them. Don't just look at strength of bond, look at how many there are.
Why is water such a good solvent?
It can participate in hydrogen bonding so almost anything containing O, N, and S can interact with it. It is polar so it can interact with anything that are also polar or ionic. It has a relatively high dielectric constant.
What does the dielectric constant value of a solvent say about its property?
Its ability to shield the charges.
What solvent would you expect to be better at dissolving based on the dielectric chart?
The one with the highest dielectric constant.
What is hydrophobicity?
Nonpolar molecules such as oil are not miscible with polar solvents such as water. Water molecules avoid touching.
What is the hydrophobic effect?
The phenomenon by which non polar molecules aggregate to avoid contact with hydrophilic molecules, particularly water. The exclusion of non polar substances from an aqueous solution.
What is the leading force that drives the hydrophobic effect?
Entropy of water molecules/solvent.
What does amphiphilic mean?
Molecules that have both hydrophobic and hydrophilic portions.
What is a micelle?
A particle with a solvated surface and a hydrophobic core. Amphiphiles may form micelles as a result of amphiphilic molecules being added to water.
What is a vesicle?
Has a hydrophilic/water core. It forms to eliminate its solvent-exposed edges, the lipid bilayer tends to close up forming a vesicle.
What is a main function that the lipid bilayer does for the cell?
It is a barrier against diffusion.
In pure water, the more H+ you have the more what?
Acidic
Solutions in which H+ > 10^-7 M= ?
Acidic
Solutions in which H+ < 10^-7 M= ?
Basic
Which condition holds more H30+ ions, acid or base?
Acid
What is the difference between H+ and H30+ ions?
H+ represents H30+ but you'll never find it in nature.
How often does a water molecule spontaneously break up into its ionic form?
1 in 55.5 million
Strong acid
They disassociate completely in water (always single, never coupled up).
Weak acid
They disassociate partially. (Some are single form, some are coupled up).
The weakest acids are where on the chart?
On the bottom of the chart because pK=-log
What does pK describe?
An acid's tendency to ionize
What is the conjugate base of the weak acid H3BO3?
H2BO3- because it lost one proton and took on negative charge.
What is the conjugate base of H2BO3-?
HBO3^2-
What is the conjugate base of HBO3^2-?
BO3^3-
Which of the following would be the strongest acid?
The strongest acid has the smallest pK. Make sure to convert pH to pK.
All weak acids can be considered what?
A buffer
A buffer can be what of its pK?
1+ or 1- of its pK