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Mind Map by Min Paul Jin Hong, updated more than 1 year ago
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Created by Min Paul Jin Hong
about 4 years ago
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AP Biology Mind Map: Water
and Life
- Polar Covalent Bonds in H2O
Molecules
- Polar Covalent Bonds: Polar covalent bonds are
bonds where the electrons are not shared equally.
In water molecules, oxygen is more
electronegative than hydrogen, so the electrons
of the covalent bonds will linger closer to oxygen
than to hydrogen.
- Polar Molecule: A polar molecule is one that its
charges are unevenly distributed. In a H2O
molecule, the oxygen is partially positive, and
the hydrgens are partially negative.
- Water's properties arise from the attractions that
exist between oppositely charged atoms of
different water molecules. The slightly positive
hydrogen atom of one molecule is attracted to
the slightly negative oxygen of a nearby molecule.
As a result, H2O molecules are held by hydrogen
bonds.
- When water is in liquid form, the hydrogen
bonds are really fragile causing H2O
molecules to form, break, and then reform
hydrogen bonds again. This means that in
water, H2O molecules are constantly forming,
breaking, and reforming hydrogen bonds with
each other.
- Polar Covalent Bonds: Polar covalent bonds are
bonds where the electrons are not shared equally.
In water molecules, oxygen is more
electronegative than hydrogen, so the electrons
of the covalent bonds will linger closer to oxygen
than to hydrogen.
- Water's Emergent Properties
- Cohesion of Water Molecules
- Cohesion: Water molecules are linked by hydrogen
bonds. These linkages make water more
structured than most other liquids. This process is
also known as the phenomenon named cohesion.
- Cohesion contributes to the transport of water and
dissolved nutrients as it resists gravity in plants. Water
from the roots reaches the leaves through a system of
water-conducting cells.
- Adhesion: This is the clinging of one
substance to another. Similarly, as
cohesion, adhesion of water to cell walls
helps counter the downward pull of
gravity.
- Surface Tension: Related to cohesion, surface tension is a measure
of how difficult it is to stretch or break the surface of a liquid. Water
compared to other liquids, has greater surface tension. The section
between water and air is an organized arrangement of water
molecules bonded to each other with hydrogen bonds, and they are
also bonded to the water below. This makes the water behave as
though covered with an invisible film.
- Cohesion: Water molecules are linked by hydrogen
bonds. These linkages make water more
structured than most other liquids. This process is
also known as the phenomenon named cohesion.
- Moderation of Temperature by Water
- Heat and Temperature
- Kinetic Energy: Kinetic energy is energy in motion. As a
result, atoms and molecules have kinetic energy because
they are constantly moving. The faster a molecule moves, the
greater its kinetic energy.
- Heat: Heat is a form of energy. The
amount of heat is a measure of the
matter’s total kinetic energy. As a
result, heat depends in part on the
matter’s volume.
- Temperature: It is the measure of heat intensity
that represents the average kinetic energy of the
molecules, indifferent of volume.
- When two objects of different temperature are brought
together, heat passes from the warmer to the cooler
object until the two are the same temperature.
- Celsius Scale: This is a scale that can indicate the
temperature.
- Calorie and Kilocalorie: It is the amount of
heat it takes to raise the temperature of 1 g
of water by 1°C. A kilocalorie is the quantity
of heat required to raise the temperature of 1
kilogram of water by 1°C.
- Joules: It is a unit of energy and one
joule equals 0.239 cal and one calorie
equals 4.184 J.
- Kinetic Energy: Kinetic energy is energy in motion. As a
result, atoms and molecules have kinetic energy because
they are constantly moving. The faster a molecule moves, the
greater its kinetic energy.
- Water's HIgh Specific Heat
- Specific Heat: The specific heat of a substance can be
determined by amount of heat that must be absorbed
or lost for 1 g of that substance to change its
temperature by 1°C. Compared to others, water's
specific heat is 1 calorie per gram and per degree
Celsius, when most other substances have a much
lower specific heat. Because of the high specific heat,
water will change its temperature less when it
absorbs or loses a given amount of heat.
- To break hydrogen bonds, heat must be absorbed, and to form
hydrogen bonds heat must be released. A calorie of heat
doesn't influence a lot the temperature of water because the
majority of the heat disrupts hydrogen bonds before the water
molecules begin to move faster. When the temperature of water
drops slightly, additional hydrogen bonds are formed, releasing
a considerable amount of energy in the form of heat.
- The high specific heat of water also serves
to stabilize ocean temperatures, creating a
favorable en- environment for marine life.
- Specific Heat: The specific heat of a substance can be
determined by amount of heat that must be absorbed
or lost for 1 g of that substance to change its
temperature by 1°C. Compared to others, water's
specific heat is 1 calorie per gram and per degree
Celsius, when most other substances have a much
lower specific heat. Because of the high specific heat,
water will change its temperature less when it
absorbs or loses a given amount of heat.
- Evaporative Cooling
- Heat of Vaporization: It is the quantity of heat a liquid must absorb for 1 g of it to be converted from
the liquid to a gas. Asides from the high specific heat, water also has a high heat of vaporization
compared to most other liquids. This is also another factor that helps with the global temperature.
- Evaporative Cooling: This is the process where a liquid evaporates, then the surface
of the liquid that remains behind cools down. This occurs as the hottest molecules,
those with the greatest kinetic energy, are more prone to leave as gas.
- Heat of Vaporization: It is the quantity of heat a liquid must absorb for 1 g of it to be converted from
the liquid to a gas. Asides from the high specific heat, water also has a high heat of vaporization
compared to most other liquids. This is also another factor that helps with the global temperature.
- Heat and Temperature
- Floating of Ice on Liquid Water
- Water is one of the few liquids that becomes less dense when turned into a solid. This means that
water the solid-state will float on liquid water. The reasoning behind is that when temperatures drops
and liquid water turns into a solid, the hydrogen bonds keep the molecules at “arm’s length,” this
makes ice about 10% less dense than liquid water at 4°C.
- This is important as if ice sank, eventually all
ponds, lakes, and even oceans would freeze
solid, making life as we know it impossible on
Earth.
- Water is one of the few liquids that becomes less dense when turned into a solid. This means that
water the solid-state will float on liquid water. The reasoning behind is that when temperatures drops
and liquid water turns into a solid, the hydrogen bonds keep the molecules at “arm’s length,” this
makes ice about 10% less dense than liquid water at 4°C.
- The Solvent of Live
- Solute Concentration in Aqueous Solutions
- Molecular Mass: Molecular mass is the sum of the atom's atomic mass in a molecule.
- Mol: It is a unit for measuring how much of a substance is there. The
benefit of measuring a number of chemicals in moles is that a mole
of one substance has exactly the same number of molecules as a
mole of any other substance.
- Molarity: It is the number of moles of solute per liter of solution. It is the unit of concentration most often
used by biologists for aqueous solutions.
- Molecular Mass: Molecular mass is the sum of the atom's atomic mass in a molecule.
- Hydrophilic and Hydrophobic Substances
- Hydrophilic: Any substance that has an attraction for water. In some
cases, substances can be hydrophilic without actually dissolving.
- Colloid: A stable suspension of fine
particles.
- Hydro Phobic: Substances that are nonionic and nonpolar, not being able
to form hydrogen bonds, and seem to repel water)
- Hydrophilic: Any substance that has an attraction for water. In some
cases, substances can be hydrophilic without actually dissolving.
- Solution, Solvent, and Solute: A liquid that is a completely
homogeneous mixture of two or more substances is called a
solution. The dissolving part of a solution is the solvent, and the
substance that is dissolved is the solute
- Aqueous Solution: In solutions where water is the solvent,
the name for the solution is an aqueous solution.
- Water is a great solvent as water it is a very versatile solvent. The reason behind this is water's polarity.
- Hydration Shell: It is the sphere of water molecules around each dissolved ion.
- A compound does not need to be ionic to dissolve in water,
such compounds dissolve when water molecules surround
each of the solute molecules, forming hydrogen bonds with
them.
- Solute Concentration in Aqueous Solutions
- Cohesion of Water Molecules
- Acids and Basic Conditions
- Buffers
- The internal pH of most living cells is close to 7. Even the smallest
change in pH can be harmful, due to the chemical processes of the
cell are very sensitive to the concentrations of hydrogen and
hydroxide ions.
- Buffer: It is a substance that minimizes changes in
the concentrations of H+ and OH- in a solution. It
does so by accepting hydrogen ions from the solution
when they are in excess and donating hydrogen ions
to the solution when they have been depleted.
- The internal pH of most living cells is close to 7. Even the smallest
change in pH can be harmful, due to the chemical processes of the
cell are very sensitive to the concentrations of hydrogen and
hydroxide ions.
- pH Scale
- pH: The pH of a solution is defined as the
negative logarithm (base 10) of the
hydrogen ion concentration:
- pH declines as H+ concentration increases. Also, the pH scale is
based on H+ concentration, it also implies OH- concentration.
- pH: The pH of a solution is defined as the
negative logarithm (base 10) of the
hydrogen ion concentration:
- Acid and Bases
- Acid: An acid is a substance that
increases the hydrogen ion
concentration of a solution.
- Base: A substance that reduces the
hydrogen ion concentration of
a solution is called a base.
- Acid: An acid is a substance that
increases the hydrogen ion
concentration of a solution.
- Acidificatoin
- When CO2 dissolves in seawater, it reacts with water to
form carbonic acid, which lowers ocean pH, a process
known as ocean acidification.
- Acid precipitation refers to rain, snow, or fog with a pH lower (more
acidic) than 5.2. (Uncontaminated rain has a pH of about 5.6, which is
slightly acidic due to the formation of carbonic acid from CO2 and
water.)
- When CO2 dissolves in seawater, it reacts with water to
form carbonic acid, which lowers ocean pH, a process
known as ocean acidification.
- Hydrogen Ion (H+), a single proton with a charge of 1+.
- Hydroxide Ion: The water molecule that lost a
proton is now a hydroxide ion (OH-), which has
a charge of 1-.
- Hydronium Ion: The proton binds to the other water
molecule, making that molecule a hydronium ion (H3O+).
- Buffers
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